IRU3038CF

Data Sheet No. PD94250 IRU3038 SYNCHRONOUS PWM CONTROLLER FOR TERMINATION POWER SUPPLY APPLICATIONS PRELIMINARY DATA SHEET FEATURES Synchronous Controller in 14-Pin Package Operating with single 5V or 12V supply voltage 200KHz to 400KHz operation set by an external resistor Soft-Start Function Fixed Frequency Voltage Mode 500mA Peak Output Drive Capability Uncommitted Error Amplifier available for DDR voltage tracking application 1.25V Reference Voltage Protects the output when control FET is shorted DESCRIPTION The IRU3038 controller IC is designed to provide a low cost synchronous Buck regulator for voltage tracking applications such DDR memory and general purpose on-board DC to DC converter. Modern micro processors combined with DDR memory, need high-speed bandwidth data bus which requires a particular bus termination voltage. This voltage will be tightly regulated to track the half of chipset voltage for best performance. The IRU3038 together with dual N-channel MOSFETs such as IRF7313, provide a low cost solution for such applications. This device features a programmable frequency set from 200KHz to 400KHz, 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 VDDQ (2.5V) C1 0.1uF C2 1uF C3 10TPB100M, 100uF, 55mV L1 1uH C4 47uF DDR Memory R1 1K R2 1K C5 0.1uF Vcc VREF VP SS Vc HDrv D1 BAT54 or 1N4148 Q1 1/2 of IRF7313 L2 Vtt 1.25V @ 3A C6 2x 6TPB150M, 150uF, 55mV U1 IRU3038 LDrv PGnd Fb Gnd D03316P-103, 10uH, 3.9A Q2 1/2 of IRF7313 Rt Comp C7 2200pF R3 33K Figure 1 - Typical application of IRU3038 when Vtt tracks the VDDQ. PACKAGE ORDER INFORMATION TA (°C) 0 To 70 0 To 70 Rev. 2.0 09/12/02 DEVICE IRU3038CF IRU3038CS PACKAGE 14-Pin Plastic TSSOP (F) 14-Pin Plastic SOIC NB (S) www.irf.com 1 IRU3038 ABSOLUTE MAXIMUM RATINGS Vcc Supply Voltage .................................................. Vc Supply Voltage ..................................................... Storage Temperature Range ...................................... Operating Junction Temperature Range ..................... 25V 30V (not rated for inductive load) -65°C To 150°C 0°C To 125°C PACKAGE INFORMATION 14-PIN PLASTIC TSSOP (F) 14-PIN PLASTIC SOIC (S) Fb 1 VP 2 VREF 3 Vcc 4 NC 5 LDrv 6 Gnd 7 14 NC 13 SS 12 Comp 11 Rt 10 Vc 9 HDrv 8 PGnd Fb 1 VP 2 VREF 3 Vcc 4 NC 5 LDrv 6 Gnd 7 14 NC 13 SS 12 Comp 11 Rt 10 Vc 9 HDrv 8 PGnd uJA=1008C/W uJA=888C/W ELECTRICAL SPECIFICATIONS Unless otherwise specified, these specifications apply over Vcc=5V, Vc=12V and TA=0 to 70°C. Typical values refer to TA=25°C. Low duty cycle pulse testing is used which keeps junction and case temperatures equal to the ambient temperature. PARAMETER Reference Voltage VREF Voltage Fb Voltage Line Regulation UVLO UVLO Threshold - Vcc UVLO Hysteresis - Vcc UVLO Threshold - Vc UVLO Hysteresis - Vc UVLO Threshold - Fb UVLO Hysteresis - Fb Supply Current Vcc Dynamic Supply Current Vc Dynamic Supply Current Vcc Static Supply Current Vc Static Supply Current Soft-Start Section Charge Current SYM V FB LREG TEST CONDITION MIN 1.225 TYP 1.250 0.2 4.2 0.25 3.3 0.2 0.6 0.1 5 7 3.5 1 -20 MAX 1.275 0.35 4.4 3.5 0.8 UNITS V % V V V V V V mA mA mA mA mA 5 > 2 gm gmZf gmZIN The error amplifier gain is independent of the transconductance under the following condition: gmZf >> 1 and gmZIN >>1 ---(14) By replacing ZIN and Zf according to Figure 7, the transformer function can be expressed as: H(s) = (1+sR7C11)3[1+sC10(R6+R8)] 1 3 sR6(C12+C11) C12C11 1+sR7 C12+C11 3(1+sR8C10) 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. fS FP3 = 2 1 C12 = 2p 3 R7 3 FP3 C12 > 50pF If not, change R7 selection. 5) Place R7 in equation (15) and calculate C10: C10 [ 2p 3 Lo 3 FO 3 Co VOSC 3 R7 VIN [ ( )] 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. The compensation network has three poles and two zeros and they are expressed as follows: Rev. 2.0 09/12/02 www.irf.com 9 IRU3038 6) Place second pole at the ESR zero. FP2 = FESR 1 R8 = 2p 3 C10 3 FP2 1 Check if R8 > gm If R8 is too small, increase R7 and start from step 2. 7) Place second zero around the resonant frequency. FZ2 = FLC R6 = 1 - R8 2p 3 C10 3 FZ2 VREF 3 R6 VOUT - VREF 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. Start to place the power components. Make all the connections 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 separate 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. 8) Use equation (1) to calculate R5: R5 = 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. 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 Vc≅ 24V) at 400KHz switching frequency and maximum gate loads. This IC's power dissipation results to an excessive temperature rise and should be considered when using IRU3038 for such an application. 10 www.irf.com Rev. 2.0 09/12/02 IRU3038 TYPICAL PERFORMANCE CHARACTERISTICS IRU3038 Output Voltage 1.3 900 IRU3038 Transconductance (GM) 800 1.28 700 Max 600 micro Mhos Min -40°C -25°C 0°C +25°C +50°C +75°C +100°C +125°C +150°C 1.26 Volts 500 400 1.24 300 1.22 200 100 1.2 0 -40°C -25°C 0°C +25°C +50°C +75°C +100°C Output Voltage Spec Max. Spec Min. Transconductance (GM) Figure 8 - Output voltage of IRU3038. Figure 9 - Transconductance of IRU3038. IRU3038 Rise Time / Fall Time C L = 1 500pF 50 45 40 35 nano Seconds (ns) 30 25 20 15 10 5 0 -40°C -25°C 0°C +25°C +50°C +75°C +100°C Rise Time Fall time Figure 10 - Rise and fall time of IRU3038. Rev. 2.0 09/12/02 www.irf.com 11 IRU3038 TYPICAL APPLICATION Single Supply 5V Input 5V D1 BAT54S L1 1uH C2 2x 10TPB100ML, 100uF, 55mV C1 33uF Tantalum C3 0.1uF C4 1uF C5 0.1uF Vcc VREF VP SS C8 0.1uF Rt C9 1800pF R4 26.1K Comp Gnd Vc HDrv Q1 IRF7460 L2 D05022P-103, 3.3uH, 10A Q2 IRF7460 2.5V @ 8A C7 2x 6TPC150M, 150uF, 40mV U1 IRU3038 LDrv PGnd R6 Fb R5 1K, 1% 1K, 1% Figure 11 - Typical application of IRU3038 in an on-board DC-DC converter using a single 5V supply. 450 400 Fs (KHz) 350 300 250 200 150 0 50 100 150 200 250 Rt (K V ) Figure 12 - Switching frequency vs. Rt. 12 www.irf.com Rev. 2.0 09/12/02 IRU3038 TYPICAL APPLICATION 5V C1 0.1uF 12V C2 1uF C3 10TPB100M, 100uF, 55mV L1 1uH 5V C4 47uF Vcc C6 0.1uF SS Vc HDrv Q1 1/2 of IRF7313 L2 V DDQ 2.5V @ 3A C7 2x 6TPC150M, 150uF, 40mV U1 IRU3037 LDrv D03316P-103, 10uH, 3.9A Q1 1/2 of IRF7313 Comp C8 2200pF R2 33K Fb Gnd R3 1K R1 1K 5V C9 0.1uF 12V C10 1uF C11 10TPB100M, 100uF, 55mV R4 1K R5 1K Vcc VR E F VP SS C12 0.15uF Vc HDrv D1 BAT54 or 1N4148 Q2 1/2 of IRF7313 L3 Vtt (1.25V @ 3A) C13 2x 6TPC150M 150uF, 40mV U2 IRU3038 LDrv PGnd Fb D03316P-103, 10uH, 3.9A Q2 1/2 of IRF7313 C14 2200pF R6 33K Rt Comp Gnd Figure 13 - Typical application of IRU3038 for DDR memory when the termination voltage tracks the core voltage generated by IRU3037. Rev. 2.0 09/12/02 www.irf.com 13 IRU3038 DEMO-BOARD APPLICATION 5V to 2.5V @ 8A 5V D1 C18 47uF 70m V V REF C3 1uF R 12 Short R13 Open R1 Open R2 Short C4 1uF C5 0.1uF C6 1uF C2 47uF 70m V L1 1uH C1 33uF Vcc V REF VP SS C8 0.1uF Rt Comp Vc HDrv Q1 L2 3.3uH C9 470pF R6 4.7 V R8 Fb Gnd R11 1K, 1% 1K, 1% 2.5V @ 8A C10 150uF 40m V C11 150uF 40m V C12 1uF Gnd V DDQ U1 IRU3038 LDrv PGnd Q2 C15 1800pF R9 26.1K Figure 14 - Demo-board application of IRU3038. Application Parts List Ref Desig Description Q1, Q2 MOSFET U1 Controller D1 Diode L1 L2 C1 C2,C18 C10,C11 C5,C8 C4 C15 C9 C3,C6,C12 R9 R6 R8,R11 Inductor Inductor Cap, Tantalum Cap, Poscap Cap, Poscap Cap, Ceramic Cap, Ceramic Cap, Ceramic Cap, Ceramic Cap, Ceramic Resistor Resistor Resistor Value Qty Part# 20V, 10mV, 12A 2 IRF7460 Synchronous PWM 1 IRU3038 Fast Switching, 1 BAT54S Schottky 1m H, 10A 1 D03316P-102HC 3.3m H, 12A 1 D05022P-332HC 33m F, 16V 1 ECS-T1CD336R 47m F, 16V, 70mV 2 16TPB47M 150m F, 6.3V, 40mV 2 6TPC150M 0.1m F, Y5V, 25V 2 ECJ-2VF1E104Z 1m F, X7R, 25V 1 ECJ-3YB1E105K 1800pF, X7R, 50V 1 ECJ-2VB1H182K 470pF, X7R 1 ECJ-2VB2D471K 1m F, Y5V, 16V 3 ECJ-2VF1C105Z 26.1K, 5% 1 4.7V, 5% 1 1K, 1% 2 Manuf IR IR IR Coilcraft Coilcraft Panasonic Sanyo Sanyo Panasonic Panasonic Panasonic Panasonic Panasonic Web site (www.) irf.com coilcraft.com maco.panasonic.co.jp sanyo.com/industrial maco.panasonic.co.jp 14 www.irf.com Rev. 2.0 09/12/02 IRU3038 TYPICAL PERFORMANCE CHARACTERISTICS 94 92 VIN Efficiency (%) 90 88 86 84 82 80 0 1 2 3 4 5 6 7 8 9 Vss VOUT Output Current (A) Figure 15 - Efficiency for IRU3038 Evaluation Board. VIN=5V, VOUT=2.5V Figure 16 - Start-up time @ IOUT=5A. Vss VOUT IOUT Figure 17 - Shutdoown the output by pulling down the soft-start. Figure 18 - 3.3V output voltage ripple @ IOUT=5A. 2A 4A 0A 0A Figure 19 - Transient response @ IOUT=0 to 2A. Rev. 2.0 09/12/02 Figure 20 - Transient response @ IOUT=0 to 4A. www.irf.com 15 IRU3038 (F) TSSOP Package 14-Pin A L Q R1 1.0 DIA B C R E M O PIN NUMBER 1 F D DETAIL A P N G J DETAIL A 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 4.90 --0.85 0.05 08 0.50 0.09 0.09 14-PIN NOM 0.65 BSC 4.40 6.40 BSC --1.00 1.00 5.00 --0.90 --128 REF 128 REF --1.00 REF 0.60 0.20 ----- MAX 4.50 0.30 5.10 1.10 0.95 0.15 88 0.75 ----- NOTE: ALL MEASUREMENTS ARE IN MILLIMETERS. 16 www.irf.com Rev. 2.0 09/12/02 IRU3038 (S) SOIC Package 14-Pin Surface Mount, Narrow Body H A B C E DETAIL-A PIN NO. 1 D 0.386 0.015 x 458 TF K L DETAIL-A I G 14-PIN SYMBOL A B C D E F G H I J K L T MIN MAX 8.56 8.74 1.27 BSC 0.51 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 J NOTE: ALL MEASUREMENTS ARE IN MILLIMETERS. Rev. 2.0 09/12/02 www.irf.com 17 IRU3038 PACKAGE SHIPMENT METHOD PKG DESIG F S PACKAGE DESCRIPTION TSSOP Plastic SOIC, Narrow Body PIN COUNT 14 14 PARTS PER TUBE 100 55 PARTS PER REEL 2500 2500 T&R Orientation Fig A Fig B 1 1 1 1 1 1 Feed Direction Figure A 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 18 www.irf.com Rev. 2.0 09/12/02