Data Sheet No. PD94173 IRU3037 / IRU3037A 8-PIN SYNCHRONOUS PWM CONTROLLER FEATURES DESCRIPTION Synchronous Controller in 8-Pin Package Operating with single 5V or 12V supply voltage Internal 200KHz Oscillator (400KHz for IRU3037A) Soft-Start Function Fixed Frequency Voltage Mode 500mA Peak Output Drive Capability Protects the output when control FET is shorted The IRU3037 controller IC is designed to provide a low cost synchronous Buck regulator for on-board DC to DC converter applications. With the migration of today's ASIC products requiring low supply voltages such as 1.8V and lower, together with currents in excess of 3A, traditional linear regulators are simply too lossy to be used when input supply is 5V or even in some cases with 3.3V input supply. The IRU3037 together with dual N-channel MOSFETs such as IRF7313, provide a low cost solution for such applications. This device features an internal 200KHz oscillator (400KHz for "A" version), under-voltage lockout for both Vcc and Vc supplies, an external programmable soft-start function as well as output under-voltage detection that latches off the device when an output short is detected. APPLICATIONS DDR memory source sink Vtt application Low cost on-board DC to DC such as 5V to 3.3V, 2.5V or 1.8V Graphic Card Hard Disk Drive TYPICAL APPLICATION 5V 12V C3 0.1uF C4 1uF Vcc SS C2 10TPB100M, 100uF, 55mV 1uH C1 47uF Vc HDrv C8 0.1uF L1 Q1 1/2 of IRF7313 U1 IRU3037 L2 D05022P-562, 5.6uH, 5.3A LDrv Q2 1/2 of IRF7313 1.5V/5A C7 2x 6TPC150M, 150uF, 40mV R3 Comp C9 2200pF Fb Gnd 249, 1% R5 1.24K, 1% R4 24k Figure 1 - Typical application of IRU3037 or IRU3037A. PACKAGE ORDER INFORMATION TA (C) 0 To 70 0 To 70 0 To 70 0 To 70 Rev. 2.7 08/22/02 DEVICE IRU3037CF IRU3037CS IRU3037ACF IRU3037ACS PACKAGE 8-Pin Plastic TSSOP (F) 8-Pin Plastic SOIC NB (S) 8-Pin Plastic TSSOP (F) 8-Pin Plastic SOIC NB (S) www.irf.com FREQUENCY 200KHz 200KHz 400KHz 400KHz 1 IRU3037 / IRU3037A ABSOLUTE MAXIMUM RATINGS Vcc Supply Voltage .................................................. Vc Supply Voltage ...................................................... Storage Temperature Range ...................................... Operating Junction Temperature Range ..................... 25V 30V (not rated for inductive load) -65C To 150C 0C To 125C PACKAGE INFORMATION 8-PIN PLASTIC TSSOP (F) Fb 1 8-PIN PLASTIC SOIC (S) Fb 1 8 SS Vcc 2 7 Comp Vcc 2 LDrv 3 6 Vc Gnd 4 5 HDrv 8 SS 7 Comp LDrv 3 6 Vc Gnd 4 5 HDrv JA=124C/W JA=160C/W ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply over Vcc=5V, Vc=12V and TA=0 to 70C. Typical values refer to TA=25C. Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the ambient temperature. PARAMETER Reference Voltage Fb Voltage Fb Voltage Line Regulation UVLO UVLO Threshold - Vcc UVLO Hysteresis - Vcc UVLO Threshold - Vc UVLO Hysteresis - Vc UVLO Threshold - Fb SYM MIN TYP MAX UNITS IRU3037 IRU3037A 5 FESR and FO [ (1/5 ~ 1/10)3 fS Use the following equation to calculate R4: R4 = 8 1 VOSC Fo3FESR R5 + R6 3 3 3 gm VIN FLC2 R5 C9 = 698pF Choose C9 = 680pF One more capacitor is sometimes added in parallel with C9 and R4. This introduces one more pole which is mainly used to supress the switching noise. The additional pole is given by: 1 FP = C9 3 CPOLE 2p 3 R4 3 C9 + CPOLE The pole sets to one half of switching frequency which results in the capacitor CPOLE: CPOLE = ---(12) www.irf.com 1 1 p3R43fS C9 fS for FP << 2 1 p3R43fS Rev. 2.7 08/22/02 IRU3037 / IRU3037A For a general solution for unconditionally stability for any type of output capacitors, in a wide range of ESR values we should implement local feedback with a compensation network. The typically used compensation network for voltage-mode controller is shown in Figure 7. VOUT ZIN R7 Zf E/A R5 Comp Ve VREF Gain(dB) 1 2p3R83C10 1 ( ) C123C11 2p3R73 C12+C11 1 2p3R73C12 1 2p3R73C11 1 1 FZ2 = 2p3C103(R6 + R8) 2p3C103R6 Cross Over Frequency: VIN 1 FO = R73C103 3 VOSC 2p3Lo3Co ---(15) Where: VIN = Maximum Input Voltage VOSC = Oscillator Ramp Voltage Lo = Output Inductor Co = Total Output Capacitors H(s) dB FZ1 FZ2 FP2 FP3 Frequency Figure 7 - Compensation network with local feedback and its asymptotic gain plot. In such configuration, the transfer function is given by: 1 - gmZf Ve = VOUT 1 + gmZIN gmZIN >>1 and ---(14) By replacing ZIN and Zf according to Figure 7, the transformer function can be expressed as: 1 3 sR6(C12+C11) (1+sR7C11)3[1+sC10(R6+R8)] C123C11 1+sR7 3(1+sR8C10) C12+C11 [ The stability requirement will be satisfied by placing the poles and zeros of the compensation network according to following design rules. The consideration has been taken to satisfy condition (14) regarding transconductance error amplifier. 1) Select the crossover frequency: Fo < FESR and Fo [ (1/10 ~ 1/6)3 fS The error amplifier gain is independent of the transconductance under the following condition: H(s)= FP3 = FZ1 = C11 R6 Fb gmZf >> 1 FP2 = C12 C10 R8 FP1 = 0 ( )] 2) Select R7, so that R7 >> 3) Place first zero before LC's resonant frequency pole. FZ1 75% FLC 1 C11 = 2p 3 FZ1 3 R7 4) Place third pole at the half of the switching frequency. FP3 = As known, transconductance amplifier has high impedance (current source) output, therefore, consider should be taken when loading the E/A output. It may exceed its source/sink output current capability, so that the amplifier will not be able to swing its output voltage over the necessary range. 2 gm C12 = fS 2 1 2p 3 R7 3 FP3 C12 > 50pF If not, change R7 selection. 5) Place R7 in (15) and calculate C10: The compensation network has three poles and two zeros and they are expressed as follows: Rev. 2.7 08/22/02 C10 [ www.irf.com 2p 3 Lo 3 Fo 3 Co VOSC 3 R7 VIN 9 IRU3037 / IRU3037A 6) Place second pole at the ESR zero. FP2 = FESR 1 R8 = 2p 3 C10 3 FP2 Check if R8 > 1 gm If R8 is too small, increase R7 and start from step 2. 7) Place second zero around the resonant frequency. FZ2 = FLC 1 R6 = - R8 2p 3 C10 3 FZ2 8) Use equation (1) to calculate R5. R5 = VREF 3 R6 VOUT - VREF These design rules will give a crossover frequency approximately one-tenth of the switching frequency. The higher the band width, the potentially faster the load transient speed. The gain margin will be large enough to provide high DC-regulation accuracy (typically -5dB to 12dB). The phase margin should be greater than 458 for overall stability. Start to place the power components, make all the connection in the top layer with wide, copper filled areas. The inductor, output capacitor and the MOSFET should be close to each other as possible. This helps to reduce the EMI radiated by the power traces due to the high switching currents through them. Place input capacitor directly to the drain of the high-side MOSFET, to reduce the ESR replace the single input capacitor with two parallel units. The feedback part of the system should be kept away from the inductor and other noise sources, and be placed close to the IC. In multilayer PCB use one layer as power ground plane and have a control circuit ground (analog ground), to which all signals are referenced. The goal is to localize the high current path to a separate loop that does not interfere with the more sensitive analog control function. These two grounds must be connected together on the PC board layout at a single point. Figure 8 shows a suggested layout for the critical components, based on the schematic on page 14. PGnd PGnd C1 C2A, B C7A, B PGnd L1 Vin Vout 8 IC Quiescent Power Dissipation Power dissipation for IC controller is a function of applied voltage, gate driver loads and switching frequency. The IC's maximum power dissipation occurs when the IC operating with single 12V supply voltage (Vcc=12V and Vc24V) at 400KHz switching frequency and maximum gate loads. Figures 9 and 10 show voltage vs. current, when the gate drivers loaded with 470pF, 1150pF and 1540pF capacitors. The IC's power dissipation results to an excessive temperature rise. This should be considered when using IRU3037A for such application. 7 6 5 L2 Q1 1 D D D C 3 2 1 5 2 3 5 4 C4 6 U1 3 IRU3037 R4 C9 7 2 C3 C8 8 R5 1 R6 4 Single Point Analog Gnd Connect to Power Ground plane Analog Gnd Analog Gnd Figure 8 - Suggested layout. (Topside shown only) Layout Consideration The layout is very important when designing high frequency switching converters. Layout will affect noise pickup and can cause a good design to perform with less than expected results. 10 www.irf.com Rev. 2.7 08/22/02 IRU3037 / IRU3037A TYPICAL PERFORMANCE CHARACTERISTICS IRU3037A Vcc vs. Icc TA = 258C Icc (mA) @470PF, 1150PF and 1540PF Gate Load 14 12 10 8 6 4 2 0 CLOAD =1540pF CLOAD =1150pF CLOAD =470pF 0 2 4 6 8 10 12 14 Vcc (V) Figure 9 - Vcc vs. Icc IRU3037A Vc vs. Ic TA = 258C @470PF, 1150PF and 1540PF Gate Load 30 Ic (ma) 25 CLOAD =1540pF 20 CLOAD =1150pF 15 10 CLOAD =470pF 5 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Vc (V) Figure 10 - Vc vs. Ic Rev. 2.7 08/22/02 www.irf.com 11 IRU3037 / IRU3037A TYPICAL PERFORMANCE CHARACTERISTICS IRU3037 Output Voltage IRU3037 Output Frequency 1.3 240 230 1.28 Max 220 Max 210 Volts Kilo Hertz 1.26 200 1.24 190 Min Min 180 1.22 170 1.2 160 -40C 0C Output Voltage +50C +100C Spec Max. +150C -40C Spec Min. 0C +50C Oscillation Frequency Figure 11 - Output Voltage +100C Spec Max. +150C Spec Min. Figure 12 - Output Frequency IRU3037 Maximum Duty Cycle 92.0% 90.0% Percent Duty Cycle 88.0% 86.0% 84.0% 82.0% 80.0% -40C -25C 0C +25C +50C +75C +100C +125C +150C Max Duty Cycle Figure 13 - Maximum Duty Cycle 12 www.irf.com Rev. 2.7 08/22/02 IRU3037 / IRU3037A TYPICAL PERFORMANCE CHARACTERISTICS IRU3037A Output Voltage IRU3037A Output Frequency 820 460 Max 440 Max 810 420 800 Kilo Hertz milli Volts 400 790 380 360 Min Min 780 340 770 320 760 300 -40C -25C 0C +25C Output Voltage +50C +75C Spec Max. +100C +150C -40C Spec Min. -25C 0C +25C Oscillation Frequency +50C +75C Spec Max. +100C +150C Spec Min. Figure 14 - Output Voltage Figure 15 - Output Frequency IRU3037 / IRU3037A Transconductance ( GM ) IRU3037 / IRU3037A Rise Time / Fall Time CL = 1500pF 1000 50 900 45 800 40 700 35 nano Seconds micro Mho's 600 500 400 30 25 20 300 15 200 10 100 5 0 0 -40C -25C 0C +25C Positive load GM +50C +75C +100C -25C 0C +25C Rise Time Negative load GM Figure 16 - Transconductance Rev. 2.7 08/22/02 -40C +50C +75C +100C Fall time Figure 17 - Rise Time and Fall Time www.irf.com 13 IRU3037 / IRU3037A TYPICAL APPLICATION Single Supply 5V Input 5V D1 1N4148 D3 1N4148 1uH D2 1N4148 C3 0.1uF C4 1uF Vcc L1 C2 2x 10TPB100ML, 100uF, 55mV C5 0.1uF Vc Q1 1/2 of IRF7301 HDrv U1 SS C8 0.1uF C1 47uF Tantalum L2 D05022P-103, 10uH, 4.3A IRU3037 Q2 1/2 of IRF7301 LDrv 3.3V @ 4A C7 2x 6TPC150M, 150uF, 40mV R6 Comp C9 680pF Fb 1.65K, 1% Gnd R4 105K R5 1K, 1% Figure 18 - Typical application of IRU3037 in an on-board DC-DC converter using a single 5V supply. 14 www.irf.com Rev. 2.7 08/22/02 IRU3037 / IRU3037A TYPICAL APPLICATION Dual Supply, 5V Bus and 12V Bias Input 5V L1 12V 1uH C4 0.1uF C2 10TPB100M, 100uF, 55m V, 1.5A rms C1 1uF C1 47uF 1.8V/1A IRU1206-18 Vcc Q1 1/2 of IRF7752 HDrv C7 0.1uF C8 2200pF C3 47uF Vc U1 SS IRU3037 2.5V/2A L2 CTX5-2P, 3.5uH @ 2.5A Q2 1/2 of IRF7752 LDrv C6 6TPB150M, 150uF, 55m V R1 Comp Fb 1K, 1% R3 1K 1% Gnd R2 14K L2 C6 CTX5-2P, 3.5uH @ 2.5A 6TPB150M, 150uF, 55m V (Qty 2) CTX10-5P, 5.7uH @ 2.5A 6TPB150M, 150uF, 55m V (Qty 1) C9 10TPB100M, 100uF, 55m V, 1.5A rms C10 0.1uF C11 1uF Vc Vcc Q3 1/2 of IRF7752 HDrv C13 0.1uF C14 2200pF R5 14K U1 SS IRU3037 CTX5-1P, 3.4uH @ 2A Q4 1/2 of IRF7752 LDrv 3.3V/1.8A L3 C12 6TPB150M, 150uF, 55m V R4 Comp Fb 1.65K, 1% Gnd R6 1K, 1% Figure 19 - Typical application of IRU3037 or IRU3037A in an on-board DC-DC converter providing the Core, GTL+, and Clock supplies for the Pentium II microprocessor. Rev. 2.7 08/22/02 www.irf.com 15 IRU3037 / IRU3037A TYPICAL APPLICATION 1.8V to 7.5V / 0.5A Boost Converter L1 1uH (CoilTronics UP2B-1R0) Vpwr (1.5V Min) C1 2x 68uF Vcc C5 1uF D1 1N5817 C9 2x 47uF R1 20K Q3 IRF7402 Q2 2N2222 R2 10K Q1 2N2222 VO U T (7.5V / 0.5A) C10 100pF C4 0.01uF C5 0.1uF R4 25K SS Comp Vc HDrv U1 IRU3037 R3 20K Fb Vcc LDrv Gnd C8 1uF Gnd R5 R6 1K, 1% 5K, 1% Figure 20 - Typical application of IRU3037 as a boost converter. 16 www.irf.com Rev. 2.7 08/22/02 IRU3037 / IRU3037A DEMO-BOARD APPLICATION 5V or 12V to 3.3V @ 10A L1 VIN 5V or 12V 1uH C2A 47uF 16V D4 LL4148 C1 33uF 16V D1 LL4148 C2B 47uF 16V D2 Gnd LL4148 C3 1uF Vcc C19 1uF C6 0.1uF Vc C8 1uF Q1 IRF7457 HDrv U1 L2 IRU3037 3.3uH SS C5 0.1uF Q2 LDrv IRF7460 C7 470pF R4 4.7V VOUT 3.3V @ 10A C9B 150uF 6.3V C9C 150uF 6.3V C13 1uF Comp Gnd C4 2200pF R6 Gnd Fb 1.65K R5 1K R3 20K Figure 21 - Demo-board application of IRU3037. Application Parts List Ref Desig Q1 Q2 U1 D1, D2, D4 L1 L2 C1 C2A, C2B C9B, C9C C5, C6 C3 C4 C7 C8, C13, C19 R3 R4 R5 R6 Rev. 2.7 08/22/02 Description MOSFET MOSFET Controller Diode Inductor Inductor Capacitor, Tantalum Capacitor, Poscap Capacitor, Poscap Capacitor, Ceramic Capacitor, Ceramic Capacitor, Ceramic Capacitor, Ceramic Capacitor, Ceramic Resistor Resistor Resistor Resistor Value Qty Part# 20V, 7mV, 15A 1 IRF7457 20V, 10mV, 12A 1 IRF7460 Synchronous PWM 1 IRU3037 Fast Switching 3 LL4148 1mH, 10A 1 D03316P-102HC 3.3mH, 12A 1 D05022P-332HC 33mF, 16V 1 ECS-T1CD336R 47mF, 16V, 70mV 2 16TPB47M 150mF, 6.3V, 40mV 2 6TPC150M 0.1mF, Y5V, 25V 2 ECJ-2VF1E104Z 1mF, X7R, 25V 1 ECJ-3YB1E105K 2200pF, X7R, 50V 1 ECJ-2VB1H222K 470pF, X7R 1 ECJ-2VB2D471K 1mF, Y5V, 16V 3 ECJ-2VF1C105Z 20K, 5% 1 4.7V, 5% 1 1K, 1% 1 1.65K, 1% 1 www.irf.com Manuf IR IR IR Coilcraft Coilcraft Panasonic Sanyo Sanyo Panasonic Panasonic Panasonic Panasonic Panasonic 17 IRU3037 / IRU3037A DEMO-BOARD WAVEFORMS IRU3037 V IN VIN=5.0V, V OUT =3.3V Efficiency (%) 100 90 V OUT 80 70 0 1 2 3 4 5 6 7 8 9 10 11 Output Current (A) Figure 22 - Efficiency for IRU3037 Evaluation Board. Figure 23 - Start-up time @ IOUT=5A. IRU3037 Vss IRU3037 V OUT IOUT = 5V Figure 24 - Shutdown the output by pulling down the soft-start. Figure 25 - 3.3V output voltage ripple @ IOUT=5A. IRU3037 IRU3037 2A 4A 0A 0A Figure 26 - Transient response @ IOUT = 0 to 2A. 18 Figure 27 - Transient response @ IOUT = 0 to 4A. www.irf.com Rev. 2.7 08/22/02 IRU3037 / IRU3037A (F) TSSOP Package 8-Pin A L Q R1 B 1.0 DIA C R E N M P O F D DETAIL A PIN NUMBER 1 DETAIL A G J H K SYMBOL DESIG A B C D E F G H J K L M N O P Q R R1 MIN 4.30 0.19 2.90 --0.85 0.05 08 0.50 0.09 0.09 8-PIN NOM 0.65 BSC 4.40 6.40 BSC --1.00 1.00 3.00 --0.90 --128 REF 128 REF --1.00 REF 0.60 0.20 ----- MAX 4.50 0.30 3.10 1.10 0.95 0.15 88 0.75 ----- NOTE: ALL MEASUREMENTS ARE IN MILLIMETERS. Rev. 2.7 08/22/02 www.irf.com 19 IRU3037 / IRU3037A (S) SOIC Package 8-Pin Surface Mount, Narrow Body H A B C E DETAIL-A PIN NO. 1 L D DETAIL-A 0.386 0.015 x 458 T K I F J G 8-PIN SYMBOL A B C D E F G H I J K L T MIN MAX 4.80 4.98 1.27 BSC 0.53 REF 0.36 0.46 3.81 3.99 1.52 1.72 0.10 0.25 78 BSC 0.19 0.25 5.80 6.20 08 88 0.41 1.27 1.37 1.57 NOTE: ALL MEASUREMENTS ARE IN MILLIMETERS. 20 www.irf.com Rev. 2.7 08/22/02 IRU3037 / IRU3037A PACKAGE SHIPMENT METHOD PKG DESIG PACKAGE DESCRIPTION PIN COUNT PARTS PER TUBE PARTS PER REEL T&R Orientation F TSSOP Plastic 8 100 2500 Fig A S SOIC, Narrow Body 8 95 2500 Fig B 1 1 1 1 Feed Direction Figure A 1 1 Feed Direction Figure B IR WORLD HEADQUARTERS: 233 Kansas St., El Segundo, California 90245, USA Tel: (310) 252-7105 TAC Fax: (310) 252-7903 Visit us at www.irf.com for sales contact information Data and specifications subject to change without notice. 02/01 Rev. 2.7 08/22/02 www.irf.com 21