1
Dual 3A 1MHz/2.5MHz High Efficiency Synchronous
Buck Regulator
ISL8036, ISL8036A
ISL8036, ISL8036A are integrated power controllers rated for
dual 3A output current or current sharing operation with a
1MHz (ISL8036)/2.5MHz (ISL8036A) step-down regulator,
which is ideal for any low power low-voltage applications. The
channels are 180° out-of-phase for input RMS current and EMI
reduction. It is optimized for generating low output voltages
down to 0.8V each. The supply voltage range is from 2.8V to
6V, allowing for the use of a single Li+ cell, three NiMH cells or
a regulated 5V input. The two channels are 180° out-of-phase,
and each one has a guaranteed minimum output current of
3A. They can be combined to form a single 6A output in the
current sharing mode. While in current sharing, the interleaved
PWM signals reduce input and output ripple.
The ISL8036, ISL8036A includes a pair of low ON-resistance
P-channel and N-channel internal MOSFETs to maximize
efficiency and minimize external component count. 100%
duty-cycle operation allows less than 250mV dropout voltage
at 3A each.
The ISL8036, ISL8036A offers an independent 1ms
Power-good (PG) timer at power-up. When shutdown, ISL8036,
ISL8036A discharges the output capacitor. Other features
include internal digital soft-start, enable for power sequence,
overcurrent protection, and thermal shutdown.
The ISL8036, ISL8036A is offered in a 24 Ld 4mmx4mm QFN
package with 1mm maximum height. The complete converter
occupies less than 1.5cm2 area.
Features
3A High Efficiency Synchronous Buck Regulator with up to
95% Efficiency
2% Output Accuracy Over-Temperature/Load/Line
Internal Digital Soft-Start - 1.5ms
6A Current Sharing Mode Operation
External Synchronization up to 6MHz
Internal Current Mode Compensation
Peak Current Limiting and Hiccup Mode Short Circuit
Protection
Reverse Overcurrent Protection
Applications
DC/DC POL Modules
•µC/µP, FPGA and DSP Power
Plug-in DC/DC Modules for Routers and Switchers
Test and Measurement Systems
Li-ion Battery Power Devices
Bar Code Reader
Related Literature
AN1616, “ISL8036CRSHEVAL1Z Current Sharing 6A Low
Quiescent Current High Efficiency Synchronous Buck
Regulator
AN1617, “ISL8036DUALEVAL1Z Dual 3A Low Quiescent
Current High Efficiency Synchronous Buck Regulator”
AN1615, “ISL8036ACRSHEVAL1Z Current Sharing 6A Low
Quiescent Current High Efficiency Synchronous Buck
Regulator
AN1618, “ISL8036ADUALEVAL1Z Dual 3A Low Quiescent
Current High Efficiency Synchronous Buck Regulator”
OUTPUT LOAD (A)
EFFICIENCY (%)
FIGURE 1. EFFICIENCY vs LOAD, 1MHz 5VIN PWM, TA = +25°C
40
50
60
70
80
90
100
0123456
3.3VOUT- PWM
CAUTION: These devices are sensitive to electrostatic discharge; follow proper IC Handling Procedures.
1-888-INTERSIL or 1-888-468-3774 |Copyright Intersil Americas Inc. 2010, 2012. All Rights Reserved
Intersil (and design) is a trademark owned by Intersil Corporation or one of its subsidiaries.
All other trademarks mentioned are the property of their respective owners.
August 17, 2012
FN6853.3
ISL8036, ISL8036A
2FN6853.3
August 17, 2012
Typical Applications
FIGURE 2. TYPICAL APPLICATION DIAGRAM - SINGLE 6A
FIGURE 3. TYPICAL APPLICATION DIAGRAM - DUAL 3A OUTPUTS
L1
1.5µH
LX1
PGND
FB1
VIN1, 2
EN1
PG1
SYNC
IN PUT 2. 8 V TO 6V OUTPUT1
1.8V/6A
C1
2x22µF
ISL8036,
ISL8036A
C2
R2
124k
R3
100k
2x22µF
VDD
SGND
C3
12pF
L2
1.5µH
FB2
C4
R6
50k
2x22µF
C6
150pF
LX2
PGND
SGND
EN2
PG2
COMP
SS
C5
22nF
L1
1.5µH
LX1
PGND
FB1
VIN
EN1
PG1
SYN C
INPUT 2.7V TO 6V OUTPUT1
1.8V/3A
C1
2x22µF ISL8036,
C2
R2
124k
R3
100k
2x22µF
VDD
SGND
C3
12pF
L2
1.5µH
FB2
OUTPUT2
1.8V/3A
C4
R5
124k
R6
100k
2x22µF C5
12pF
LX2
PGND
SGND
EN2
PG2
COMP
SS
ISL8036A
ISL8036, ISL8036A
3FN6853.3
August 17, 2012
TABLE 1. COMPONENT VALUE SELECTION FOR DUAL OPERATION
VOUT 0.8V 1.2V 1.5V 1.8V 2.5V 3.3V
C1 2x22µF 2x22µF 2x22µF 2x22µF 2x22µF 2x22µF
C2 (or C4) 2X22µF 2X22µF 2X22µF 2X22µF 2X22µF 2X22µF
L1 (or L2)* 1.0~2.2µH 1.0~2.2µH 1.0~2.2µH 1.0~3.3µH 1.0~3.3µH 1.0~4.7µH
R2 (or R5) 0 50k 87.5k 124k 212.5k 312.5k
R3 (or R6) 100k 100k 100k 100k 100k 100k
*For ISL8036A, the values used for L1 (or L2) are half the values specified above for each VOUT.
TABLE 2. COMPONENT VALUE SELECTION FOR CURRENT SHARING OPERATION
VOUT 0.8V 1.2V 1.5V 1.8V 2.5V 3.3V
C1 2x22µF 2x22µF 2x22µF 2x22µF 2x22µF 2x22µF
C2 (or C4) 2X22µF 2X22µF 2X22µF 2X22µF 2X22µF 2X22µF
L1 (or L2)* 1.0~2.2µH 1.0~2.2µH 1.0~2.2µH 1.0~3.3µH 1.0~3.3µH 1.0~4.7µH
R2 0 50k 87.5k 124k 212.5k 312.5k
R3 100k 100k 100k 100k 100k 100k
R6 30k 33k 31k 30k 29k 28k
C6 250pF 180pF 150pF 150pF 150pF 150pF
*For ISL8036A, the values used for L1 (or L2) are half the values specified above for each VOUT.
NOTE: C5 value (22nF) is given by Equation 1 corresponding to the desired soft-start time.
TABLE 3. SUMMARY OF DIFFERENCES
PART NUMBER SWITCHING FREQUENCY
ISL8036 Internally fixed switching frequency FSW = 1MHz
ISL8036A Internally fixed switching frequency FSW = 2.5MHz
ISL8036, ISL8036A
4FN6853.3
August 17, 2012
Block Diagram
LX1
++
CSA1
+
+
+
SLOPE
COMP
STAR
T
SOFT-
START
0.8V EAMP COMP
PWM
LOGIC
CONTROLLER
PROTECTION
DRIVER
FB1
+
0.736V
0.864V
PG1 SYNC
SHUTDOWN
VIN1
PGND
OSCILLATOR
+
BANDGAP
SCP
+
0.5V
EN1
SHUTDOWN
1ms
DELAY
0.3pF
27pF
390k
SGND
3pF
1.6k
LX2
++
CSA2
+
+
+
SLOPE
COMP
STAR
T
SOFT-
START
0.8V EAMP COMP PWM
LOGIC
CONTROLLER
PROTECTION
DRIVER
FB2
+
0.736V
0.864V
PG2
SHUTDOWN
VIN2
PGND
+
BANDGAP
SCP
+
0.5V
EN2
SHUTDOWN
1ms
DELAY
SGND
3pF
1.6k
1M
THERMAL
SHUTDOWN SHUTDOWN
COMP
VIN2
1M
VIN1
OCP
THRESHOLD
LOGIC
SS
SS 0.3pF
27pF
390k
ISL8036, ISL8036A
5FN6853.3
August 17, 2012
Pin Configuration
ISL8036, ISL8036A
(24 LD QFN)
TOP VIEW
LX2
PGND2
PGND2
PGND1
PGND1
LX1
COMP
NC
FB1
SGND
PG1
SYNC
LX2
VIN2
VIN2
EN2
PG2
FB2
LX1
VIN1
VIN1
VDD
SS
EN1
1
2
3
4
5
6
18
17
16
15
14
13
24 23 22 21 20 19
789101112
25
PAD
Pin Descriptions
PIN
NUMBER SYMBOL DESCRIPTION
1, 24 LX2 Switching node connection for Channel 2. Connect to one terminal of inductor for VOUT2.
22, 23 PGND2 Negative supply for the power stage of Channel 2.
4 EN2 Regulator Channel 2 enable pin. Enable the output, VOUT2, when driven to high. Shutdown the VOUT2 and discharge
output capacitor when driven to low. Do not leave this pin floating.
5 PG2 1ms timer output. At power-up or EN HI, this output is a 1ms delayed Power-Good signal for the VOUT2 voltage.
6 FB2 The feedback network of the Channel 2 regulator. To be connected to FB1 (current sharing)
7 COMP An additional external network across COMP and SGND is required to improve the loop compensation of the amplifier
channel parallel operation. The soft-start pin should be tied to the external capacitor. COMP pin is NC in dual mode
operation, using internal compensation. If SS pin is tied to CSS (without connection to VIN), external compensation is
automtaically used. Connect an external R,C network on COMP pin for parallel mode operation.
8 NC No connect pin; please tie to GND.
9 FB1 The feedback network of the Channel 1 regulator. FB1 is the negative input to the transconductance error amplifier.
The output voltage is set by an external resistor divider connected to FB1. With a properly selected divider, the output
voltage can be set to any voltage between the power rail (reduced by converter losses) and the 0.8V reference. There
is an internal compensation to meet a typical application. In addition, the regulator power-good and undervoltage
protection circuitry use FB1 to monitor the Channel 1 regulator output voltage.
10 SGND System ground.
11 PG1 1ms timer output. At power-up or EN HI, this output is a 1ms delayed Power-Good signal for the VOUT1 voltage.
12 SYNC Connect to logic high or input voltage VIN . Connect to an external function generator for external Synchronization.
Negative edge trigger. Do not leave this pin floating. Do not tie this pin low (or to SGND).
13 EN1 Regulator Channel 1 enable pin. Enable the output, VOUT1, when driven to high. Shutdown the VOUT1 and discharge
output capacitor when driven to low. Do not leave this pin floating.
ISL8036, ISL8036A
6FN6853.3
August 17, 2012
14 SS SS is used to adjust the soft-start time. When SS pin is tied to VIN, SS time is 1.5ms. SS pin is tied to VIN only in dual
mode operation. SS pin is tied to CSS only in parallel mode operation, using only external compensation. Connect a
capacitor from SS to SGND to adjust the soft-start time (current sharing). CSS should not be larger than 33nF. This
capacitor, along with an internal 5µA current source sets the soft-start interval of the converter, tSS.
15 VDD Input supply voltage for the logic. VDD to be at the same potential as VIN +0.3/-0.5V.
20, 21 PGND1 Negative supply for the power stage of Channel 1.
18, 19 LX1 Switching node connection for Channel 1. Connect to one terminal of inductor for VOUT1.
16, 17
2, 3
VIN1,
VIN2
Input supply voltage. Connect 22µF ceramic capacitor to power ground per channel.
25 PAD The exposed pad must be connected to the SGND pin for proper electrical performance. Add as much vias as possible
for optimal thermal performance.
Pin Descriptions (Continued)
PIN
NUMBER SYMBOL DESCRIPTION
CSS μF[] 6.25 tSS s[]=(EQ. 1)
Ordering Information
PART NUMBER
(Notes 2, 3)
PART
MARKING
TEMP. RANGE
(°C)
PACKAGE
(Pb-free)
PKG.
DWG. #
ISL8036IRZ 80 36IRZ -40 to +85 24 Ld 4x4 QFN L24.4x4D
ISL8036IRZ-T (Note 1) 80 36IRZ -40 to +85 24 Ld 4x4 QFN L24.4x4D
ISL8036AIRZ 80 36AIRZ -40 to +85 24 Ld 4x4 QFN L24.4x4D
ISL8036AIRZ-T (Note 1) 80 36AIRZ -40 to +85 24 Ld 4x4 QFN L24.4x4D
ISL8036CRSHEVAL1Z Evaluation Board
ISL8036DUALEVAL1Z Evaluation Board
ISL8036ACRSHEVAL1Z Evaluation Board
ISL8036ADUALEVAL1Z Evaluation Board
NOTES:
1. Please refer to TB347 for details on reel specifications.
2. These Intersil Pb-free plastic packaged products employ special Pb-free material sets, molding compounds/die attach materials, and 100% matte tin plate plus
anneal (e3 termination finish, which is RoHS compliant and compatible with both SnPb and Pb-free soldering operations). Intersil Pb-free products are MSL
classified at Pb-free peak reflow temperatures that meet or exceed the Pb-free requirements of IPC/JEDEC J STD-020.
3. For Moisture Sensitivity Level (MSL), please see device information page for ISL8036, ISL8036A. For more information on MSL, please see Technical
Brief TB363.
ISL8036, ISL8036A
7FN6853.3
August 17, 2012
Table of Contents
Absolute Maximum Ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Thermal Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Recommended Operating Conditions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
Electrical Specifications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8
ISL8036 Typical Operating Performance for Dual PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 10
ISL8036A Typical Operating Performance for Dual PWM Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 15
ISL8036 Typical Operating Performance for Current Sharing PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 17
ISL8036A Typical Operating Performance for Current Sharing PWM Operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 21
Theory of Operation. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
PWM Control Scheme . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Synchronization Control . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Output Current Sharing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
Overcurrent Protection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
PG . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 22
UVLO . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Enable . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Soft-start-up . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Discharge Mode (Soft-Stop) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Power MOSFETs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
100% Duty Cycle . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Thermal Shutdown . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Applications Information . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Output Inductor and Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Output Voltage Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
Input Capacitor Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 23
PCB Layout Recommendation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 24
Revision History. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Products . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 25
Package Outline Drawing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 26
ISL8036, ISL8036A
8FN6853.3
August 17, 2012
Absolute Maximum Ratings (Reference to SGND) Thermal Information
VIN1, VIN2, VDD . . . . . . . . . . . . . . . . . . . . . -0.3V to 6.5V (DC) or 7V (20ms)
LX1, LX2 . . . . . . . . . . . . . -3V/(10ns)/-1.5V (100ns)/-0.3V (DC) to 6.5V (DC) or
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 7V (20ms)/8.5V(10ns)
EN1, EN2, PG1, PG2, SYNC, SS. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to +6.5V
FB1, FB2, COMP . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 2.7V
NC . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3V to 0.3V
ESD Ratings
Human Body Model (Tested per JESD22-A114) . . . . . . . . . . . . . . . . . 4kV
Charged Device Model (Tested per JESD22-C101E). . . . . . . . . . . . . . 2kV
Machine Model (Tested per JESD22-A115). . . . . . . . . . . . . . . . . . . . 300V
Latch Up (Tested per JESD-78A; Class 2, Level A) . . . . . . . . . . . . . . 100mA
Thermal Resistance (Typical) θJA (°C/W) θJC (°C/W)
24 Ld 4x4 QFN (Notes 4, 5). . . . . . . . . . . 36 2
Junction Temperature Range . . . . . . . . . . . . . . . . . . . . . . .-55°C to +150°C
Storage Temperature Range. . . . . . . . . . . . . . . . . . . . . . . .-65°C to +150°C
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
Pb-Free Reflow Profile . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . see link below
http://www.intersil.com/pbfree/Pb-FreeReflow.asp
Recommended Operating Conditions
VIN Supply Voltage Range. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 2.85V to 6V
Load Current Range per Channel . . . . . . . . . . . . . . . . . . . . . . . . . . . 0A to 3A
Ambient Temperature Range . . . . . . . . . . . . . . . . . . . . . . . . -40°C to +85°C
CAUTION: Do not operate at or near the maximum ratings listed for extended periods of time. Exposure to such conditions may adversely impact product
reliability and result in failures not covered by warranty.
NOTES:
4. θJA is measured in free air with the component mounted on a high effective thermal conductivity test board with “direct attach” features. See Tech
Brief TB379.
5. For θJC, “case temperature” location is at the center of the exposed metal pad on the package underside.
Electrical Specifications Unless otherwise noted, the typical specifications are measured at the following conditions:
TA = -40°C to +85°C, VIN = 3.6V, EN1 = EN2 = VDD, L = 1.5µH, C1 = C2 = C4 = 2x22µF, IOUT1 = IOUT2 = 0A to 3A, unless otherwise noted. Typical values
are at TA = +25°C. Boldface limits apply over the operating temperature range, -40°C to +85°C.
PARAMETER SYMBOL TEST CONDITIONS
MIN
(Note 6) TYP
MAX
(Note 6) UNITS
INPUT SUPPLY
VIN Undervoltage Lockout Threshold VUVLO Rising 2.5 2.85 V
Hysteresis 50 100 mV
Quiescent Supply Current IVDD SYNC = VDD, EN1 = EN2 = VDD,
FS = 1MHz, no load at the output
15 40 mA
FS = 2.5MHz, no load at the output 30 70 mA
Shutdown Supply Current ISD VDD = 6V, EN1 = EN2 = SGND 8 20 µA
OUTPUT REGULATION
FB1, FB2 Regulation Voltage VFB 0.790 0.8 0.810 V
FB1, FB2 Bias Current IFB VFB = 0.75V 0.1 µA
Load Regulation SYNC = VDD, output load from 0A to 6A 2 mV/A
Line Regulation VIN = VO + 0.5V to 6V (minimal 2.85V) 0.1 %/V
Soft-start Ramp Time Cycle SS = VDD 1.5 ms
Soft-start Charging Current ISS 456µA
COMPENSATION
Error Amplifier Trans-Conductance SS = VDD 20 µA/V
SS with Capacitor 100 µA/V
Trans-resistance RT 0.180 0.2 0.220
Trans-resistance Matching RT_match -0.03 +0.03
OVERCURRENT PROTECTION
Dynamic Current Limit ON-time tOCON 17 Clock pulses
Dynamic Current Limit OFF-time tOCOFF 8 SS cycle
Positive Peak Overcurrent Limit Ipoc1 4.1 4.8 5.5 A
Ipoc2 4.1 4.8 5.5 A
Negative Peak Overcurrent Limit Inoc1 -3.5 -2.5 -1.5 A
Inoc2 -3.5 -2.5 -1.5 A
ISL8036, ISL8036A
9FN6853.3
August 17, 2012
LX1, LX2
P-Channel MOSFET ON-Resistance VIN = 6V, IO = 200mA 50 75 m
VIN = 2.7V, IO = 200mA 70 100 m
N-Channel MOSFET ON-Resistance VIN = 6V, IO = 200mA 50 75 m
VIN = 2.7V, IO = 200mA 70 100 m
LX_ Maximum Duty Cycle 100 %
PWM Switching Frequency FSISL8036 0.88 1.1 1.32 MHz
ISL8036A 2.15 2.5 2.85 MHz
Synchronization Frequency Range FSYNC ISL8036 (Note 7) 2.64 6 MHz
Channel 1 to Channel 2 Phase Shift Rising edge to rising edge timing 180 °
LX Minimum On Time SYNC = High (PWM mode) 140 ns
Soft Discharge Resistance RDIS EN = LOW 80 100 120
LX Leakage Current Pulled up to 6V 0.1 1µA
PG1, PG2
Output Low Voltage Sinking 1mA, VFB = 0.7V 0.3 V
PG Pin Leakage Current PG = VIN = 6V 0.01 0.1 µA
Internal PGOOD Low Rising Threshold Percentage of nominal regulation voltage 89.5 92 94.5 %
Internal PGOOD Low Falling Threshold Percentage of nominal regulation voltage 85 88 91 %
Delay Time (Rising Edge) Time from VOUT_ reached regulation 1 ms
Internal PGOOD Delay Time
(Falling Edge)
710 µs
EN1, EN2, SYNC
Logic Input Low 0.4 V
Logic Input High 1.5 V
SYNC Logic Input Leakage Current ISYNC Pulled up to 6V 0.1 1µA
Enable Logic Input Leakage Current IEN Pulled up to 6V 0.1 1µA
Thermal Shutdown 150 °C
Thermal Shutdown Hysteresis 25 °C
NOTES:
6. Parameters with MIN and/or MAX limits are 100% tested at +25°C, unless otherwise specified. Temperature limits established by characterization and
are not production tested.
7. The operational frequency per switching channel will be half of the SYNC frequency.
Electrical Specifications Unless otherwise noted, the typical specifications are measured at the following conditions:
TA = -40°C to +85°C, VIN = 3.6V, EN1 = EN2 = VDD, L = 1.5µH, C1 = C2 = C4 = 2x22µF, IOUT1 = IOUT2 = 0A to 3A, unless otherwise noted. Typical values
are at TA = +25°C. Boldface limits apply over the operating temperature range, -40°C to +85°C. (Continued)
PARAMETER SYMBOL TEST CONDITIONS
MIN
(Note 6) TYP
MAX
(Note 6) UNITS
ISL8036, ISL8036A
10 FN6853.3
August 17, 2012
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz.
FIGURE 4. EFFICIENCY, VIN =3.3V, T
A = +25°C FIGURE 5. EFFICIENCY, VIN = 5V, TA = +25°C
FIGURE 6. POWER DISSIPATION, VOUT = 1.8V, TA = +25°C FIGURE 7. VOUT REGULATION vs LOAD, 1.8V, TA = +25°C
FIGURE 8. OUTPUT VOLTAGE REGULATION vs VIN, 1.8V, TA = +25°C FIGURE 9. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
40
50
60
70
80
90
100
0.00.51.01.52.02.53.0
IOUT (A)
EFFICIENCY (%)
1.5VOUT
1.2VOUT
2.5VOUT
1.8VOUT
40
50
60
70
80
90
100
0.0 0.5 1.0 1.5 2.0 2.5 3.0
IOUT (A)
EFFICIENCY (%)
1.5V
OUT
1.2VOUT
2.5VOUT
1.8VOUT
3.3VOUT
0
0.2
0.4
0.6
0.8
1.0
1.2
0.0 0.5 1.0 1.5 2.0 2.5 3.0
IOUT (A)
PD (W)
3.3VIN
5VIN
1.780
1.785
1.790
1.795
1.800
1.805
1.810
0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT LOAD (A)
OUTPUT VOLTAGE (V)
3.3VIN
5VIN
2.7VIN
1.780
1.785
1.790
1.795
1.800
1.805
1.810
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
3A LOAD 2A LOAD 0A LOAD
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 0.5A/DIV
ISL8036, ISL8036A
11 FN6853.3
August 17, 2012
FIGURE 10. STEADY STATE OPERATION AT NO LOAD CHANNEL 2 FIGURE 11. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 1
FIGURE 12. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 2 FIGURE 13. LOAD TRANSIENT CHANNEL 1
FIGURE 14. LOAD TRANSIENT CHANNEL 2 FIGURE 15. SOFT-START WITH NO LOAD CHANNEL 1
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
LX2 2V/DIV
VOUT2 RIPPLE 20mV/DIV
IL2 0.5A/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
LX2 2V/DIV
VOUT RIPPLE 20mV/DIV
IL2 2A/DIV
VOUT RIPPLE 50mV/DIV
IL1 2A/DIV
VOUT2 RIPPLE 20mV/DIV
IL2 2A/DIV
EN1 2V/DIV
VOUT 1V/DIV
IL1 0.5A/DIV
PG1 5V/DIV
ISL8036, ISL8036A
12 FN6853.3
August 17, 2012
FIGURE 16. SOFT-START WITH NO LOAD CHANNEL 2 FIGURE 17. SOFT-START AT FULL LOAD CHANNEL 1
FIGURE 18. SOFT-START AT FULL LOAD CHANNEL 2 FIGURE 19. SOFT-DISCHARGE SHUTDOWN CHANNEL 1
FIGURE 20. SOFT-DISCHARGE SHUTDOWN CHANNEL 2 FIGURE 21. STEADY STATE OPERATION CHANNEL 1 AT NO LOAD
WITH FSW = 2.4MHz
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
EN2 2V/DIV
VOUT2 0.5V/DIV
IL2 0.5A/DIV
PG2 5V/DIV
EN1 2V/DIV
VOUT1 1V/DIV
IL1 2A/DIV
PG1 5V/ D IV
EN2 2V/DIV
VOUT2 0.5V/DIV
IL2 2A/DIV
PG2 5V/ D IV
EN1 5V/DIV
VOUT1 0.5V/DIV
IL1 0.5A/DIV
PG1 5V/D IV
EN2 2V/DIV
VOUT2 0.5V/DIV
IL2 0.5A/DIV
PG2 5V/ D IV
LX1 2V/DIV
VOUT1 RIPPLE 20mV/DIV
IL1 1A /DIV
SYNCH 5V/DIV
ISL8036, ISL8036A
13 FN6853.3
August 17, 2012
FIGURE 22. STEADY STATE OPERATION CHANNEL 2 AT NO LOAD
WITH FSW = 2.4MHz
FIGURE 23. STEADY STATE OPERATION CHANNEL 1 AT FULL LOAD
WITH FSW = 2.4MHz
FIGURE 24. STEADY STATE OPERATION CHANNEL 2 AT FULL LOAD
WITH FSW = 2.4MHz
FIGURE 25. STEADY STATE OPERATION CHANNEL 1 AT NO LOAD
WITH FSW = 6MHz
FIGURE 26. STEADY STATE OPERATION CHANNEL 2 AT NO LOAD
WITH FSW = 5MHz
FIGURE 27. OUTPUT SHORT CIRCUIT CHANNEL 1
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
LX2 2V/DIV
VOUT2 RIPPLE 20mV/DIV
IL2 1A/DIV
SYNCH 5V/DIV
LX1 2V/DIV
VOUT1 RIPPLE 20mV/DIV
IL1 2A/DIV
SYNCH 5V/DIV
LX2 2V/DIV
VOUT2 RIPPLE 20mV/DIV
IL2 2A/DIV
SYNCH 5V/DIV
VOUT1 RIPPLE 20mV/DIV
IL1 2A/DIV
SYNCH 5V/DIV LX1 2V/D IV
LX2 2V/DIV
VOUT2 RIPPLE 20mV/DIV
IL2 2A/DIV
SYNCH 5V/DIV
PHASE1 5V/DIV
IL1 1A/DIV
PG1 5V/DIV
VOUT1 1V/DIV
ISL8036, ISL8036A
14 FN6853.3
August 17, 2012
FIGURE 28. OUTPUT SHORT CIRCUIT RECOVERY (FROM HICCUP)
CHANNEL 1
FIGURE 29. OUTPUT SHORT CIRCUIT CHANNEL 2
FIGURE 30. OUTPUT SHORT CIRCUIT RECOVERY (FROM HICCUP) CHANNEL 2
ISL8036 Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, FSW = 1MHz. (Continued)
PHASE1 5V/DIV
IL1 1A/DIV
PG1 5V/DIV
VOUT1 1V/DIV
PHASE2 5V/DIV
IL2 1A/DIV
PG2 5V/DIV
VOUT2 0. 5 V/DIV
PHASE2 5V/D IV
IL2 1A/DIV
PG2 5V/DIV
VOUT2 1V/DIV
ISL8036, ISL8036A
15 FN6853.3
August 17, 2012
ISL8036A Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, L1 = L2 = 0.6µH,
FSW = 2.5MHz.
FIGURE 31. EFFICIENCY vs LOAD, 3.3VIN DUAL CHANNEL 1,
TA = +25°C
FIGURE 32. EFFICIENCY vs LOAD, 5VIN DUAL CHANNEL 1,
TA = +25°C
FIGURE 33. POWER DISSIPATION vs LOAD, 1.8VOUT DUAL CHANNEL 1,
TA = +25°C
FIGURE 34. VOUT REGULATION vs LOAD, 1.8VOUT DUAL CHANNEL 1,
TA = +25°C
FIGURE 35. VOUT REGULATION vs VIN, 1.8VOUT DUAL CHANNEL 1,
TA = +25°C
FIGURE 36. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
40
50
60
70
80
90
100
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT LOAD (A)
2.5VOUT
1.2VOUT 1.8VOUT
1.5VOUT
EFFICIENCY (%)
40
50
60
70
80
90
100
0.0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT LOAD (A)
EFFICIENCY (%)
1.2VOUT 1.8VOUT
1.5VOUT
2.5VOUT 3.3VOUT
0.00
0.25
0.50
0.75
1.00
1.25
1.50
0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT LOAD (A)
POWER DISSIPATION (W)
3.3VIN
5VIN
2.7VIN
1.780
1.785
1.790
1.795
1.800
1.805
1.810
0 0.5 1.0 1.5 2.0 2.5 3.0
OUTPUT LOAD (A)
OUTPUT VOLTAGE (V)
3.3VIN
5VIN 2.7VIN
1.780
1.785
1.790
1.795
1.800
1.805
1.810
2.5 3.0 3.5 4.0 4.5 5.0 5.5
INPUT VOLTAGE (V)
OUTPUT VOLTAGE (V)
1.5A LOAD3A LOAD 0A LOAD
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 0.5A/D IV
ISL8036, ISL8036A
16 FN6853.3
August 17, 2012
FIGURE 37. STEADY STATE OPERATION AT NO LOAD CHANNEL 2 FIGURE 38. STEADY STATE OPERATION AT FULL LOAD CHANNEL 1
FIGURE 39. STEADY STATE OPERATION AT FULL LOAD CHANNEL 2 FIGURE 40. LOAD TRANSIENT CHANNEL 1
FIGURE 41. LOAD TRANSIENT CHANNEL 2
ISL8036A Typical Operating Performance for Dual PWM Operation
Unless otherwise noted, operating conditions are: VOUT1 = 1.8V; VOUT2 = 0.8V; IOUT1 = 0A to 3A; IOUT2 = 0A to 3A, L1 = L2 = 0.6µH,
FSW = 2.5MHz. (Continued)
LX1 1V/DIV
VOUT RIPPLE 20mV/DIV
IL1 0.5A/D IV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
LX1 1V/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
IL1 2A/DIV
VOUT1 RIPPLE 50mV/DIV
IL1 2A/DIV
VOUT1 RIPPLE 50mV/DIV
IL1 2A/DIV
ISL8036, ISL8036A
17 FN6853.3
August 17, 2012
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 +I
OUT2 = 0A to 6A, FSW = 1MHz.
FIGURE 42. EFFICIENCY vs LOAD, VIN =3.3V, T
A = +25°C FIGURE 43. EFFICIENCY vs LOAD, VIN =5V, T
A = +25°C
FIGURE 44. POWER DISSIPATION vs LOAD, 1.8V, TA = +25°C FIGURE 45. VOUT REGULATION vs LOAD, 1.8V, TA = +25°C
FIGURE 46. VOUT REGULATION vs LOAD, 1.8V, TA = -40°C FIGURE 47. VOUT REGULATION vs LOAD, 1.8V, TA = +85°C
0123456
OUTPUT LOAD (A)
40
50
60
70
80
90
100
EFFICIENCY (%)
1.8VOUT
1.2VOUT
1.5VOUT
2.5VOUT
40
50
60
70
80
90
100
0123456
OUTPUT LOAD (A)
EFFICIENCY (%)
1.8VOUT
1.2VOUT
1.5VOUT
2.5VOUT
3.3VOUT
0.0
0.5
1.0
1.5
2.0
2.5
3.0
0OUTPUT LOAD (A)
POWER DISSIPATION (W)
123456
3.3VIN
2.7VIN
5VIN
1.790
1.795
1.800
1.805
1.810
1.815
1.820
0123456
OUTPUT LOAD (A)
OUTPUT VOLTAGE (V)
3.3VIN 5VIN
2.7VIN
1.785
1.790
1.795
1.800
1.805
1.810
1.815
OUTPUT LOAD (A)
OUTPUT VOLTAGE (V)
02 51346
3.3VIN
5VIN
2.7VIN
1.790
1.795
1.800
1.805
1.810
1.815
1.820
0123456
OUTPUT LOAD (A)
OUTPUT VOLTAGE (V)
3.3VIN
5VIN
2.7VIN
ISL8036, ISL8036A
18 FN6853.3
August 17, 2012
FIGURE 48. OUTPUT VOLTAGE REGULATION vs VIN, TA = +25°C FIGURE 49. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
FIGURE 50. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 1 FIGURE 51. STEADY STATE OPERATION WITH FULL LOAD CHANNEL 2
FIGURE 52. STEADY STATE OPERATION AT NO LOAD CHANNEL 1
AND 2
FIGURE 53. STEADY STATE OPERATION AT FULL LOAD CHANNEL 1
AND 2
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 +I
OUT2 = 0A to 6A, FSW = 1MHz. (Continued)
1.790
1.795
1.800
1.805
1.810
1.815
1.820
2.5 3.0 3.5 4.0 4.5 5.0 5.5
OUTPUT VOLTAGE (V)
0A
4A
6A
INPUT VOLTAGE (V)
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 0.5A/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
LX2 2V/D IV
VOUT RIPPLE 20mV/DIV
IL2 2A/DIV
LX1 5V/DIV
IL2 1A/DIV
LX2 5V/DIV
IL1 1A/DIV
LX1 5V/DIV
IL2 1A/DIV
LX2 5V/DIV
IL1 1A/DIV
ISL8036, ISL8036A
19 FN6853.3
August 17, 2012
FIGURE 54. LOAD TRANSIENT CHANNEL 1 FIGURE 55. SOFT-START WITH NO LOAD CHANNEL 1
FIGURE 56. SOFT-START AT FULL LOAD CHANNEL 1 FIGURE 57. SOFT-DISCHARGE SHUTDOWN CHANNEL 1
FIGURE 58. STEADY STATE OPERATION CH1 AT NO LOAD WITH
FSW = 3MHz
FIGURE 59. STEADY STATE OPERATION CH1 AT FULL LOAD WITH
FSW = 3MHz
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 +I
OUT2 = 0A to 6A, FSW = 1MHz. (Continued)
VOUT RIPPLE 50mV/DIV
IL1 2A/DIV
EN1 2V/DIV
VOUT 1V/DIV
IL1 0.5A/DIV
PG1 5V/DIV
EN1 2V/DI V
VOUT 1V/DIV
IL1 2A/DIV
PG1 5V/DIV
EN1 5V/DIV
VOUT 0.5V/DIV
IL1 0.5A/DIV
PG1 5V/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 1A/DIV
SYNC 5V/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
SYNC 5V/DIV
ISL8036, ISL8036A
20 FN6853.3
August 17, 2012
FIGURE 60. STEADY STATE OPERATION CH1 AT NO LOAD WITH
FSW = 6MHz
FIGURE 61. STEADY STATE OPERATION CH1 AT FULL LOAD WITH
FSW = 6MHz
FIGURE 62. OUTPUT SHORT CIRCUIT CHANNEL 1 FIGURE 63. OUTPUT SHORT CIRCUIT RECOVERY (FROM HICCUP)
CHANNEL 1
ISL8036 Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 +I
OUT2 = 0A to 6A, FSW = 1MHz. (Continued)
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 1A/DIV
SYNC 5V/DIV
LX1 2V/DIV
VOUT RIPPLE 20mV/DIV
IL1 2A/DIV
SYNC 5V/DIV
PHASE1 5V/DIV
IL1 1A/DIV
PG1 5V/DIV
VOUT 1V/DIV
PHASE1 5V/DIV
IL1 1A/DIV
PG1 5V/DIV
VOUT 1V/DIV
ISL8036, ISL8036A
21 FN6853.3
August 17, 2012
ISL8036A Typical Operating Performance for Current Sharing PWM
Operation
Unless otherwise noted, operating conditions are: VOUT = 1.8V, IOUT1 +I
OUT2 = 0A to 6A, L1 = L2 = 0.6µH, FSW = 2.5MHz.
FIGURE 64. STEADY STATE OPERATION AT NO LOAD FIGURE 65. STEADY STATE OPERATION AT FULL 6A LOAD
LX1 5V/DIV
VOUT RIPPLE 20mV/DIV
LX2 5V/DIV
LX1 5V/DIV
VOUT RIPPLE 20mV/DIV
LX2 5V/DIV
ISL8036, ISL8036A
22 FN6853.3
August 17, 2012
Theory of Operation
The ISL8036, ISL8036A is a dual 3A or current sharing 6A
step-down switching regulator optimized for battery-powered or
mobile applications. The regulator operates at 1MHz (ISL8036) or
2.5MHz (ISL8036A) fixed switching frequency under heavy load
condition. The two channels are 180° out-of-phase operation. The
supply current is typically only 8µA when the regulator is shutdown.
PWM Control Scheme
Pulling the SYNC pin HI (>1.5V) forces the converter into PWM mode
in the next switching cycle regardless of output current. Each of the
channels of the ISL8036, ISL8036A employ the current-mode
pulse-width modulation (PWM) control scheme for fast transient
response and pulse-by-pulse current limiting, as shown in the “Block
Diagram” on page 4 with waveforms in Figure 66. The current loop
consists of the oscillator, the PWM comparator COMP, current
sensing circuit, and the slope compensation for the current loop
stability. The current sensing circuit consists of the resistance of the
P-channel MOSFET when it is turned on and the current sense
amplifier CSA1. The gain for the current sensing circuit is typically
0.2V/A. The control reference for the current loops comes from the
error amplifier EAMP of the voltage loop.
The PWM operation is initialized by the clock from the oscillator.
The P-channel MOSFET is turned on at the beginning of a PWM
cycle and the current in the MOSFET starts to ramp up. When the
sum of the current amplifier CSA1 (or CSA2 on Channel 2) and the
compensation slope (0.46V/µs) reaches the control reference of
the current loop, the PWM comparator COMP sends a signal to the
PWM logic to turn off the P-MOSFET and to turn on the N-channel
MOSFET. The N-MOSFET stays on until the end of the PWM cycle.
Figure 66 shows the typical operating waveforms during the PWM
operation. The dotted lines illustrate the sum of the compensation
ramp and the current-sense amplifier CSA_ output.
The output voltage is regulated by controlling the reference
voltage to the current loop. The bandgap circuit outputs a 0.8V
reference voltage to the voltage control loop. The feedback signal
comes from the VFB pin. The soft-start block only affects the
operation during the start-up and will be discussed separately.
The error amplifier is a transconductance amplifier that converts
the voltage error signal to a current output. The voltage loop is
internally compensated with the 27pF and 390k RC network.
The maximum EAMP voltage output is precisely clamped to the
bandgap voltage (1.172V).
Synchronization Control
The frequency of operation can be synchronized up to 6MHz by
an external signal applied to the SYNC pin. The 1st falling edge
on the SYNC triggered the rising edge of the PWM ON pulse of
Channel 1. The 2nd falling edge of the SYNC triggers the rising
edge of the PWM ON pulse of the Channel 2. This process
alternate indefinitely allowing 180° output phase operation
between the two channels.
Output Current Sharing
The ISL8036, ISL8036A dual outputs are paralleled for
multi-phase operation in order to support a 6A output. Connect
the FBs together and connect all the COMPs together. Channel 1
and Channel 2 will be 180° out-of-phase. In parallel configuration,
external soft-start should be used to ensure proper full loading
start-up. Before using full load in current sharing mode, PWM
mode should be enabled. Likewise, multiple regulators can be
paralleled by connecting the FBs, COMPs, and SS for higher
current capability. External compensation is required.
Overcurrent Protection
CAS1 and CSA2 are used to monitor Output 1 and Output 2
channels respectively. The overcurrent protection is realized by
monitoring the CSA output with the OCP threshold logic, as
shown in Figure 4. The current sensing circuit has a gain of
0.2V/A, from the P-MOSFET current to the CSA_ output. When
the CSA1 output reaches the threshold, the OCP comparator is
tripped to turn off the P-MOSFET immediately. The overcurrent
function protects the switching converter from a shorted output by
monitoring the current flowing through the upper MOSFETs.
Upon detection of overcurrent condition, the upper MOSFET will
be immediately turned off and will not be turned on again until
the next switching cycle. Upon detection of the initial overcurrent
condition, the Overcurrent Fault Counter is set to 1 and the
Overcurrent Condition Flag is set from LOW to HIGH. If, on the
subsequent cycle, another overcurrent condition is detected, the
OC Fault Counter will be incremented. If there are 17 sequential
OC fault detections, the regulator will be shutdown under an
Overcurrent Fault Condition. An Overcurrent Fault Condition will
result with the regulator attempting to restart in a hiccup mode
with the delay between restarts being 8 soft-start periods. At the
end of the eighth soft-start wait period, the fault counters are
reset and soft-start is attempted again. If the overcurrent
condition goes away prior to the OC Fault Counter reaching a
count of four, the Overcurrent Condition Flag will set back to LOW.
If the negative output current reaches -2.5A, the part enters
Negative Overcurrent Protection. At this point, all switching stops
and the part enters tri-state mode while the pull-down FET is
discharging the output until it reaches normal regulation voltage,
then the IC restarts.
PG
There are two independent power-good signals. PG1 monitors
the Output Channel 1 and PG2 monitors the Output Channel 2.
When powering up, the open-collector Power-on Reset output
holds low for about 1ms after VO reaches the preset voltage. The
PG_ output also serves as a 1ms delayed Power-Good signal.
FIGURE 66. PWM OPERATION WAVEFORMS
VEAMP
VCSA1
Duty
Cycle
IL
VOUT
ISL8036, ISL8036A
23 FN6853.3
August 17, 2012
UVLO
When the input voltage is below the undervoltage lock out (UVLO)
threshold, the regulator is disabled.
Enable
The enable (EN) input allows the user to control the turning on or
off the regulator for purposes such as power-up sequencing.
When the regulator is enabled, there is typically a 600µs delay
for waking up the bandgap reference. Then the soft start-up
begins.
Soft-start-up
The soft-start-up eliminates the inrush current during the
start-up. The soft-start block outputs a ramp reference to both
the voltage loop and the current loop. The two ramps limit the
inductor current rising speed as well as the output voltage speed
so that the output voltage rises in a controlled fashion. At the
very beginning of the start-up, the output voltage is less than
0.5V; hence the PWM operating frequency is 1/2 of the normal
frequency.
When the IC ramps up at start-up, it can't sink current even at
PWM mode, behaving like in diode emulated mode for the
soft-start time.
Discharge Mode (Soft-Stop)
When a transition to shutdown mode occurs, or the output
undervoltage fault latch is set, its output discharges to PGND
through an internal 100Ω switch.
Power MOSFETs
The power MOSFETs are optimize for best efficiency. The
ON-resistance for the P-MOSFET is typically 50mΩ and the
ON-resistance for the N-MOSFET is typical 50mΩ.
100% Duty Cycle
The ISL8036, ISL8036A features 100% duty cycle operation to
maximize the battery life. When the battery voltage drops to a
level that the ISL8036, ISL8036A can no longer maintain the
regulation at the output, the regulator completely turns on the
P-MOSFET. The maximum drop-out voltage under the 100%
duty-cycle operation is the product of the load current and the
ON-resistance of the P-MOSFET.
Thermal Shutdown
The ISL8036, ISL8036A has built-in thermal protection. When the
internal temperature reaches +150°C, the regulator is completely
shutdown. As the temperature drops to +125°C, the ISL8036,
ISL8036A resumes operation by stepping through a soft start-up.
Applications Information
Output Inductor and Capacitor Selection
To consider steady state and transient operation, ISL8036,
ISL8036A typically uses a 1.5µH output inductor. Higher or lower
inductor value can be used to optimize the total converter system
performance. For example, for a higher output voltage 3.3V
application, in order to decrease the inductor current ripple and
output voltage ripple, the output inductor value can be increased.
The inductor ripple current can be expressed in Equation 2:
The inductor’s saturation current rating needs be at least larger than
the peak current. The ISL8036, ISL8036A protects the typical peak
current 4.8A. The saturation current needs be over 4.8A for maximum
output current application.
ISL8036, ISL8036A uses an internal compensation network and the
output capacitor value is dependent on the output voltage. The
ceramic capacitor is recommended to be X5R or X7R. The
recommended minimum output capacitor values for the ISL8036,
ISL8036A are shown in Table 4.
In Table 4, the minimum output capacitor value is given for
different output voltages to make sure the whole converter
system is stable.
Output Voltage Selection
The output voltage of the regulator can be programmed via an
external resistor divider, which is used to scale the output voltage
relative to the internal reference voltage and feed it back to the
inverting input of the error amplifier. Refer to Figure 2.
The output voltage programming resistor, R2 (or R5 in
Channel 2), will depend on the desired output voltage of the
regulator. The value for the feedback resistor is typically between
0Ω and 750kΩ. Let R2 = 124kΩ, then R3 will be:
For better performance, add 12pF in parallel with R2. If the
output voltage desired is 0.8V, then leave R3 unpopulated and
short R2.
Input Capacitor Selection
The main functions for the input capacitor are to provide
decoupling of the parasitic inductance and to provide filtering
function to prevent the switching current flowing back to the
battery rail. One 22µF X5R or X7R ceramic capacitor is a good
starting point for the input capacitor selection per channel.
TABLE 4. OUTPUT CAPACITOR VALUE vs VOUT ISL8036, ISL8036A
VOUT
(V)
COUT
(µF)
L
(µH)
0.8 2 x 22 1.0~2.2
1.2 2 x 22 1.0~2.2
1.6 2 x 22 1.0~2.2
1.8 2 x 22 1.0~3.3
2.5 2 x 22 1.0~3.3
3.3 2 x 6.8 1.0~4.7
3.6 10 1.0~4.7
ΔI
VO1VO
VIN
---------
⎝⎠
⎜⎟
⎛⎞
Lf
S
---------------------------------------
=
(EQ. 2)
R3R2x0.8V
VOUT 0.8V
-----------------------------------
=(EQ. 3)
ISL8036, ISL8036A
24
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accurate and reliable. However, no responsibility is assumed by Intersil or its subsidiaries for its use; nor for any infringements of patents or other rights of third
parties which may result from its use. No license is granted by implication or otherwise under any patent or patent rights of Intersil or its subsidiaries.
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FN6853.3
August 17, 2012
For additional products, see www.intersil.com/product_tree
PCB Layout Recommendation
The PCB layout is a very important converter design step to make
sure the designed converter works well. For ISL8036, ISL8036A,
the power loop is composed of the output inductor L’s, the output
capacitor COUT1 and COUT2, the LX’s pins, and the PGND pin. It is
necessary to make the power loop as small as possible and the
connecting traces among them should be direct, short and wide.
The switching node of the converter, the LX_ pins, and the traces
connected to the node are very noisy, so keep the voltage
feedback trace away from these noisy traces. The FB network
should be as close as possible to its FB pin. SGND should have one
single connection to PGND. The input capacitor should be placed
as closely as possible to the VIN pin. Also, the ground of the input
and output capacitors should be connected as closely as
possible. The heat of the IC is mainly dissipated through the
thermal pad. Maximizing the copper area connected to the
thermal pad is preferable. In addition, a solid ground plane is
helpful for better EMI performance. It is recommended to add at
least 5 vias ground connection within the pad for the best
thermal relief.
ISL8036, ISL8036A
25 FN6853.3
August 17, 2012
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Revision History
The revision history provided is for informational purposes only and is believed to be accurate, but not warranted. Please go to web to make sure you
have the latest Rev.
DATE REVISION CHANGE
July 18, 2012 FN6853.3 page 5
Comments added, COMP pin:
COMP pin is NC in dual mode operation, using internal compensation. If SS pin is tied to CSS (without VIN connection),
external compensation is automatically used. Connect an external R,C network on COMP pin for parallel mode
operation.
Comments added, SS pin:
When SS pin is tied to VIN, SS time is 1.5ms. SS pin is tied to VIN only in dual mode operation.
SS pin is tied to CSS only in parallel mode operation, using only external compensation.
page 6 Ordering Information table, added evals:
ISL8036ACRSHEVAL1Z, ISL8036ADUALEVAL1Z, ISL8036CRSHEVAL1Z, ISL8036DUALEVAL1Z
page 15
Figure 33 title correction: "1.8VIN" on the title of these is changed to "1.8VOUT".
Figure 34 title correction: "1.8VIN" on the title of these is changed to "1.8VOUT"
Figure 35 title correction: "1.8VIN" on the title of these is changed to "1.8VOUT"
page 18, Figure 48, deleted "1.8V" in the title since the condition is mentioned in the page header.
page 22
Line 4 in Overcurrent Protection paragraph, instead of "Figure 66" changed to "Figure 4".
"with the delay between restarts being 4 soft-start periods" changed to "with the delay between restarts being 8
soft-start periods".
"end of the fourth soft-start wait period" to "end of the eighth soft-start wait period"
October 14, 2011 FN6853.2 Added “Related Literature” on page 1.
In the “Absolute Maximum Ratings” on page 8, changed:
“LX1, LX2....-1.5V (100ns)/-0.3V (DC) to 6.5V (DC) or 7V (20ms)”
to:
“LX1, LX2....-3V/(10ns)/-1.5V (100ns)/-0.3V (DC) to 6.5V (DC) or 7V (20ms)/8.5V(10ns)”
October 12, 2010 FN6853.1 In Table 3 on page 3, corrected FSW for ISL8036 from 1Hz to 1MHz.
September 28, 2010 FN6853.0 Initial release.
ISL8036, ISL8036A
26 FN6853.3
August 17, 2012
Package Outline Drawing
L24.4x4D
24 LEAD QUAD FLAT NO-LEAD PLASTIC PACKAGE
Rev 2, 10/06
0 . 90 ± 0 . 1
5
C0 . 2 REF
TYPICAL RECOMMENDED LAND PATTERN
0 . 05 MAX.
( 24X 0 . 6 )
DETAIL "X"
( 24X 0 . 25 )
0 . 00 MIN.
( 20X 0 . 5 )
( 2 . 50 )
SIDE VIEW
( 3 . 8 TYP )
BASE PLANE
4
TOP VIEW
BOTTOM VIEW
712
24X 0 . 4 ± 0 . 1
13
4.00
PIN 1 18
INDEX AREA
24
19
4.00 2.5
0.50
20X
4X
SEE DETAIL "X"
- 0 . 05
+ 0 . 07
24X 0 . 23
2 . 50 ± 0 . 15
PIN #1 CORNER
(C 0 . 25)
1
SEATING PL AN E
0.08 C
0.10 C
C
0.10 M C A B
AB
(4X) 0.15
located within the zone indicated. The pin #1 indentifier may be
Unless otherwise specified, tolerance : Decimal ± 0.05
Tiebar shown (if present) is a non-functional feature.
The configuration of the pin #1 identifier is optional, but must be
between 0.15mm and 0.30mm from the terminal tip.
Dimension b applies to the metallized terminal and is measured
Dimensions in ( ) for Reference Only.
Dimensioning and tolerancing conform to AMSE Y14.5m-1994.
6.
either a mold or mark feature.
3.
5.
4.
2.
Dimensions are in millimeters.1.
NOTES: