Features
• 500 nA input quiescent current at VIN=3.6 V (not switching)
•94% typical efficiency at 1 mA load (VIN=3.6 V, VOUT=3.3 V)
• 100% duty cycle
• 1.8 V to 5.5 V input operating range
• Undervoltage lockout: 1.57 V (VIN falling, typ.)
• Up to 400 mA output current capability
• Low power control operation for the best efficiency
• Embedded soft-start circuit
• Tiny external components: L=2.2 µH typ.
• Selectable output voltages: 1.8 V to 3.3 V
• Output voltage Power Good
• ±1.5% output voltage accuracy (VOUT, TA=25 °C)
• Dynamic output voltage selection (D0, D1)
• Available in Flip-Chip package
Applications
• Wearable applications
• Personal tracking monitors
• Smart watches, sport bands
• Energy harvesting, wireless sensors
• Wearable and fitness accessories
• Industrial sensors, portable low power devices
• Single cell Li-Ion battery applications
• Bluetooth® low energy
• Zigbee
Description
The ST1PS01 is a nano-quiescent miniaturized synchronous step-down converter,
which is able to provide up to 400 mA output current with an input voltage ranging
from 1.8 V to 5.5 V. This converter is specifically designed for applications where high
efficiency, PCB size and thickness are the key factors. The output voltage can be set
using two digital control inputs, a VOUT from 1.8 V to 3.3 V can be dynamically
selected. Thanks to the enhanced PCC (peak current control) the ST1PS01 reaches
very high efficiency conversion using just a 2.2 µH inductor and two small capacitors.
Advanced design circuitry is implemented to minimize the quiescent current. The
device is available in Flip-Chip package.
Product status link
ST1PS01
Product summary
Order code
ST1PS01AJR
ST1PS01DJR
ST1PS01EJR
Output voltages
1.9 V, 2.0 V, 2.1 V,
2.8 V (A vers.)
1.8 V, 2.3 V, 2.5 V,
2.8 V (D vers.)
1.8 V, 2.7 V, 3.0 V,
3.3 V (E vers.)
Package
Flip-Chip
(1.11x1.41mm)
400 µm pitch
400 mA nano-quiescent synchronous step-down converter with digital voltage
selection and Power Good
ST1PS01
Datasheet
DS12799 - Rev 2 - December 2018
For further information contact your local STMicroelectronics sales office.
www.st.com
1Application schematic
Figure 1. ST1PS01 application schematic
ST1PS01
EN
VIN
D0
D1
PGOOD
SW
VOUT
VOUT
GND
Low voltage system
VIN
COUT
CIN
H/L
H/L
RPU
L
GND
Vcc GPIO
Table 1. Typical external components
Component Description Value Size - imperial (metric)
CIN Ceramic capacitor with low ESR values 10 µF 0603 (1608)
COUT Ceramic capacitor with low ESR values 10 µF 0603 (1608)
L Inductor 2.2 µH 0806 (2016)
RPU Pull-up resistor 1 MΩ 0402 (1005)
ST1PS01
Application schematic
DS12799 - Rev 2 page 2/20
2Pin configuration (top through view)
Figure 2. Flip-Chip8 package
D1
D0
PGOOD
VIN
SW
VOUT
EN
GND
A
B
C
D
E
1 2 3
Table 2. Pin description
Name Bump name Description
VIN A3 Input supply voltage. Bypass this pin to ground with a 10 µF capacitor
SW C3 Switching node. Inductor connection
VOUT E3 Sense pin used to monitor output voltage
EN B2 Enable pin. High logic level turns on the IC. VIN referred
GND D2 Ground
D1 A1 Output voltage selection inputs (Refer to the Table 7. Output voltage settings for order codes and
configuration matrix)
D0 C1
PGOOD E1 Open drain output. It is in high impedance when the output voltage reaches 97.5% of the target VOUT
ST1PS01
Pin configuration (top through view)
DS12799 - Rev 2 page 3/20
3Functional pin description
GND
Device ground pin.
VIN
Supply voltage. This pin supplies power to the internal analog and digital circuitries when voltage is higher than
VUVLO. Bypass this pin to GND with a 10 μF ceramic capacitor. Input capacitor CIN must be chosen with low ESR
to reduce the input voltage ripple.
SW
Inductor connection to internal PMOS and NMOS switches.
VOUT
Output voltage sense input. It provides the feedback voltage level to the regulation circuitry. 10 µF output
capacitor COUT must be connected close to the pin or through a short trace and should have low ESR to reduce
the output voltage ripple.
EN
Enable pin. A logic low level on this pin disables the device. High level enables the device. Do not leave this pin
floating.
D1, D2
Output voltage selection pins. See the Table 7. Output voltage settings for VOUT selection. Do not leave these
pins floating. These pins can be dynamically changed during operation.
PGOOD
Power Good open drain output. If used it requires a pull-up resistor to hold a high level signal. High impedance
indicates that VOUT is above proper good threshold.
ST1PS01
Functional pin description
DS12799 - Rev 2 page 4/20
4Maximum ratings
Table 3. Absolute maximum ratings
Symbol Parameter Value Unit
VIN Power and signal supply voltage - 0.3 to + 6.5 V
EN, D0, D1 Logic input pins - 0.3 to + 6.5 V
VOUT, SW Output signal monitoring and switching pins -0.3 to VIN + 0.3 V
PGOOD Power Good open drain output pin - 0.3 to + 6.5 V
TAMB Operating ambient temperature -40 to 85 °C
TJJunction temperature -40 to 125 °C
TSTG Storage temperature -55 to 150 °C
Note: Absolute maximum ratings are those values beyond which damage to the device may occur. Functional
operation under these conditions is not implied
Table 4. Thermal data
Symbol Parameter Flip-Chip8 Unit
RthJA Thermal resistance junction-ambient 60 °C/W
Table 5. Recommended operating conditions
Symbol Parameter Min. Typ. Max. Unit
VIN Input supply voltage 1.8 5.5 V
ST1PS01
Maximum ratings
DS12799 - Rev 2 page 5/20
5Electrical characteristics
CIN= 10 µF, COUT= 10 µF, L=2.2 µH, VIN=3.6 V, VEN= VIN, VOUT=1.8 V, TA=25 °C unless otherwise specified.
Table 6. Electrical characteristics
Symbol Parameter Test conditions Min. Typ. Max. Unit
General section
IQ Quiescent current EN=VIN, IOUT=0 µA, VOUT=1.8 V, device does not
switch, VIN=2.5 V to 5.5 V 500 1000 nA
ISD Shutdown current EN=GND, shutdown current into VIN 10 200 nA
VUVLO Undervoltage lockout threshold
VIN rising 1.63 1.72 V
VIN falling 1.51 1.57 V
Hysteresis 65 mV
Vth100%+ 100% mode leave threshold VIN rising, 100% mode is disabled with VIN =
VOUTnom + Vth100%+
300
mV
Vth100%- 100% mode enter threshold VIN falling, 100% mode is entered with VIN = VOUTnom
+ Vth100%-
200
Output voltage
VOUT
Output voltage range Output voltages are selected with pins D0, D1 1.8 3.3 V
Output voltage accuracy VIN = 3.6 V, whole VOUT range, IOUT=100 mA -1.5 1.5 %
tONmin Minimum on-time VIN = 3.6 V, VOUT= 2 V, IOUT= 0 mA 200 ns
tOFFmin Minimum off-time VIN=2.3V 50 ns
tstartupd Start-up delay time VEN from low to high, VIN = 3.6 V, VOUT = 1.8 V 0.5 4 ms
ROUTDIS Output discharge MOSFET on-
resistance VEN= GND 30 Ω
Logic inputs (EN, D0, D1)
VIL Low level input voltage threshold
VIN=1.8 V to 5.5 V
0.3
V
VIH High level input voltage threshold 1
Power switch
RDS(on)
High-side MOSFET on-resistance VIN = 3.6 V, Isw = 400 mA 0.38 0.45
Ω
Low-side MOSFET on-resistance 0.14 0.2
ILIM1
High-side MOSFET switch
current limit 1.8 V ≤ VIN ≤ 5.5 V
580 700 820
mA
Low-side MOSFET switch current
limit 500
ILIMSS High-side MOSFET switch
current limit during soft-start
Reduced switch current limit during soft-start period
(typ. 400 µs) 200 280 360
Power Good output (PGOOD)
Vthpg-
Power Good threshold voltage
Rising output voltage on VOUT pin, referred to VOUT
selected (D0, D1) 95 97.5
%
VthpgH Hysteresis. To see plot for temperature variation -6 -4.25 -2.5
VOL Low level output voltage 1.8 V ≤ VIN ≤ 5.5 V, EN = GND, current into PGOOD
pin, IPGOOD = 4 mA 0.23 V
ST1PS01
Electrical characteristics
DS12799 - Rev 2 page 6/20
Table 7. Output voltage settings
Device D1 D0 VOUT
ST1PS01AJR
0 0 1.9 V
0 1 2.0 V
1 0 2.1 V
1 1 2.8 V
ST1PS01DJR
0 0 1.8 V
0 1 2.3 V
1 0 2.5 V
1 1 2.8 V
ST1PS01EJR
0 0 1.8 V
0 1 2.7 V
1 0 3.0 V
1 1 3.3 V
ST1PS01
Electrical characteristics
DS12799 - Rev 2 page 7/20
6ST1PS01 block diagram
Figure 3. Block diagram
d
EN
VIN
D0
D1
PGOOD
SW
VOUT
GND
Bandgap/Bias
CTRL
Logic
PWM
Vref
VOUT
Vref
VIN
VFB
VIN
L
Cout
Soft-start
ramp
VSW
Zero-
crossing
comp.
High
current
mode
Cin
Rpu
Vout
selection
logic
VIN
Vth100%
VIN
Vuvlo
UVLO comp.
Driver/
anti-cross
conduction
circuitry
Vref
VSW
-
+
+
+
Compensation
VFB
TON
VSW
VOUT
Pulse freq.
detection
Min. ON time
Min. OFF time
100%
mode
comp.
Peak and valley
CURRENT LIMIT
-
+
-
+
+
-
-
+
Output
discharge
ST1PS01
ST1PS01 block diagram
DS12799 - Rev 2 page 8/20
7Operation description
The ST1PS01 is an ultra-low quiescent new generation buck converter. It targets a very small quiescent current
consumption (typical 500 nA) and it guarantees high efficiency operation even down to few microampere loads.
It is based on a hysteretic comparator that senses the coil ripple current that is always held constant in all
operation modes. The device has seamless transition between PFM (pulse frequency modulation) and PWM
(pulse width modulation) mode with low ripple and good load transient response.
In order to maintain constant ripple current on the selected coil, the device changes switching frequency, which
also depends on input supply voltage. During PWM mode (heavy load), the device operates in continuous
conduction up to 400 mA and switching frequency can reach 2 MHz maximum.
7.1 Power save mode
At light load the device enters automatically power save mode with total current consumption from the input power
supply of 500 nA typical; during this condition most of the internal blocks are turned off in order to reach ultra-low
power consumption. During this time, the load current is supported by the output capacitor.
7.2 Output voltage
The device allows output voltage selection without external resistor divider. A couple of standard digital inputs are
used to configure the device to supply a fixed output voltage according to Table 7. Output voltage settings. The
VOUT pin must be connected directly and as close as possible to the inductor terminal to obtain the best
performance and get the best output voltage regulation. The output voltage can be dynamically changed to
implement voltage scaling.
7.3 Output discharge and UVLO
The device embeds a fast output discharge circuitry active when the enable pin is held to ground (EN=gnd) or
when the input supply voltage reaches the minimum voltage level set by the UVLO protection circuit
(undervoltage lock-out protection circuit). The UVLO rising threshold at 1.63 V (typ.) guarantees a proper device
supply voltage operation.
7.4 Soft-start and current limitation
The device embeds a fixed soft-start circuit active during a limited time period (few ms). This feature allows the
inrush current to be minimized from the power supply in case of weak source. During this period internal circuit
reduces to 280 mA the typical switch current limit.
7.5 100% duty cycle operation
The device enters 100% duty cycle operation if the input voltage comes close to the selected output voltage.
During this mode, the regulator is turned off and output pin is directly connected to the input pin through the high-
side MOSFET. The output voltage follows the input level minus the voltage drop across the internal MOSFET and
the inductor. Once the input voltage exceeds the 100% duty cyle leave threshold, the device restarts to switch and
regulates the select output voltage again.
7.6 Power Good flag
The Power Good comparator monitors the selected VOUT voltage. The Power Good open drain output is in high
impedance when the VOUT reaches the correct voltage level while it switches to low level when VOUT falls below
the normal voltage level.
ST1PS01
Operation description
DS12799 - Rev 2 page 9/20
8Typical performance characteristics
Figure 4. Efficiency vs load, VOUT= 1.8 V
0%
10%
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.001 0.01 0.1 1 10 100 1000
Efficiency [%]
Load current [mA]
VIN 2.8V
VIN 3.2V
VIN 3.6V
VIN 4.2V
VIN 5V
L = 2.2µH
COUT = 10µF
Figure 5. Efficiency vs VIN, VOUT= 1.8 V
60%
65%
70%
75%
80%
85%
90%
95%
2 2.5 3 3.5 4 4.5 5 5.5 6
Efficiency [%]
Input Voltage [V]
Iout = 100µA
Iout = 1mA
Iout = 50mA
Iout = 100mA
Iout = 200mA
L = 2.2µH
COUT = 10µF
Figure 6. Efficiency vs load, VOUT= 3.3 V
20%
30%
40%
50%
60%
70%
80%
90%
100%
0.001 0.01 0.1 1 10 100 1000
Efficiency [%]
Load current [mA]
VIN 3.6V
VIN 4.2V
VIN 5V
L = 2.2µH
COUT = 10µF
Figure 7. Efficiency vs VIN, VOUT= 3.3 V
60%
65%
70%
75%
80%
85%
90%
95%
100%
3.3 3.8 4.3 4.8 5.3 5.8
Efficiency [%]
Input voltage [V]
Iout = 100µA
Iout = 1mA
Iout = 50mA
Iout = 100mA
Iout = 200mA
L = 2.2µH
COUT = 10µF
ST1PS01
Typical performance characteristics
DS12799 - Rev 2 page 10/20
Figure 8. 100% mode, VOUT = 1.8 V Figure 9. 100% mode, VOUT = 3.0 V
Figure 10. VOUT change, 1.8 V to 3.3 V to 1.8 V,
IOUT=5 mA
Figure 11. Output ripple, VIN=3.6 V, VOUT =1.8 V,
IOUT=10 µA
Figure 12. Output ripple, VIN=3.6 V, VOUT =1.8 V,
IOUT=10 mA
Figure 13. Output ripple, VIN=3.6 V, VOUT =1.8 V,
IOUT=50 mA
ST1PS01
Typical performance characteristics
DS12799 - Rev 2 page 11/20
Figure 14. Output ripple, VIN=3.6 V, VOUT =1.8 V,
IOUT=150 mA
Figure 15. Output ripple, VIN=3.6 V, VOUT =1.8 V,
IOUT=250 mA
Figure 16. Start-up, VIN=3.6 V, VOUT=1.8 V, no load Figure 17. Disable, VIN=3.6 V, VOUT =1.8 V, no load
Figure 18. Start-up, VIN=3.6 V, VOUT=1.8 V, IOUT=100
mA
Figure 19. Disable, VIN=3.6 V, VOUT =1.8 V, IOUT=100
mA
ST1PS01
Typical performance characteristics
DS12799 - Rev 2 page 12/20
Figure 20. Load transient, VIN=3.6 V, VOUT=1.8 V,
IOUT=50 µA to 10 mA
Figure 21. Load transient, VIN=3.6 V, VOUT=1.8 V,
IOUT=0 to 100 mA
Figure 22. Load transient, VIN=3.6 V, VOUT=1.8 V, IOUT=0 to 100 mA
ST1PS01
Typical performance characteristics
DS12799 - Rev 2 page 13/20
9Package information
In order to meet environmental requirements, ST offers these devices in different grades of ECOPACK®
packages, depending on their level of environmental compliance. ECOPACK® specifications, grade definitions
and product status are available at: www.st.com. ECOPACK® is an ST trademark.
9.1 Flip-Chip 8 (1.14x1.44 mm) package information
Figure 23. Flip-Chip 8 (1.14x1.44 mm) package outline
ST1PS01
Package information
DS12799 - Rev 2 page 14/20
Table 8. Flip-Chip 8 (1.14x1.44 mm) mechanical data
Symbol
Milimeters
Min. Typ. Max.
A 0.500 0.550 0.600
A1 0.170 0.200 0.230
A2 0.330 0.350 0.370
b 0.230 0.250 0.270
D 1.08 1.11 1.14
D1 0.624
E 1.38 1.41 1.44
E1 1.00
fE 0.205
fD 0.243
eE 0.250
eD 0.312
e 0.50
J 0.40
ccc 0.05
Figure 24. Flip-Chip 8 (1.14x1.44 mm) recommended footprint
ST1PS01
Flip-Chip 8 (1.14x1.44 mm) package information
DS12799 - Rev 2 page 15/20
9.2 Flip-Chip 8 (1.14x1.44 mm) packing information
Figure 25. Flip-Chip 8 (1.14x1.44 mm) tape outline
Figure 26. Flip-Chip 8 (1.14x1.44 mm) tape orientation
1
A
MARKING
1
A
1
A
MARKING
MARKING
ST1PS01
Flip-Chip 8 (1.14x1.44 mm) packing information
DS12799 - Rev 2 page 16/20
Figure 27. Flip-Chip 8 (1.14x1.44 mm) reel outline
Table 9. Reel mechanical data
A max. N min. W1 max. [mm] W2 max. [mm] W3 min./max. [mm]
180 60 8.4 14.4 7.9/10.9
ST1PS01
Flip-Chip 8 (1.14x1.44 mm) packing information
DS12799 - Rev 2 page 17/20
Contents
1Application schematic .............................................................2
2Pin configuration (top through view) ...............................................3
3Functional pin description .........................................................4
4Maximum ratings ..................................................................5
5Electrical characteristics...........................................................6
6Block diagram .....................................................................8
7Operation description..............................................................9
7.1 Power save mode ..............................................................9
7.2 Output voltage .................................................................9
7.3 Output discharge and UVLO .....................................................9
7.4 Soft-start and current limitation ...................................................9
7.5 100% duty cycle operation .......................................................9
7.6 Power Good flag ...............................................................9
8Typical performance characteristics ..............................................10
9Package information..............................................................14
9.1 Flip-Chip8 (1.14x1.44 mm) package information....................................14
9.2 Flip-Chip 8 (1.14x1.44 mm) packing information....................................15
Revision history .......................................................................18
ST1PS01
Contents
DS12799 - Rev 2 page 19/20
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ST1PS01
DS12799 - Rev 2 page 20/20
