APU3037A

Technology Licensed from International Rectifier APU3037 / APU3037A 8-PIN SYNCHRONOUS PWM CONTROLLER DESCRIPTION The APU3037 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 APU3037 together with dual N-channel MOSFETs such as AP60T03, 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. FEATURES Synchronous Controller in 8-Pin Package Operating with single 5V or 12V supply voltage Internal 200KHz Oscillator (400KHz for APU3037A) Soft-Start Function Fixed Frequency Voltage Mode 500mA Peak Output Drive Capability Protects the output when control FET is shorted RoHS Compliant 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 C2 10TPB100M, 100uF, 55mV L1 1uH C1 47uF Vcc Vc HDrv Q1 AP60T03GH 1N4148 LDrv Q2 AP60T03GH R3 249, 1% Gnd R5 1.24K, 1% L2 1.5V/5A 5.6uH, 5.3A C7 2x 6TPC150M, 150uF, 40mV SS/SD C8 0.1uF U1 APU3037 C9 2200pF R4 24k Comp Fb Figure 1 - Typical application of APU3037 or APU3037A. PACKAGE ORDER INFORMATION TA (°C) 0 To 70 0 To 70 0 To 70 0 To 70 DEVICE APU3037O APU3037M/MP APU3037AO APU3037AM/AMP PACKAGE FREQUENCY 8-Pin Plastic TSSOP (O) 200KHz 8-Pin Plastic SOIC NB (M/MP) 200KHz 8-Pin Plastic TSSOP (O) 400KHz 8-Pin Plastic SOIC NB (M/MP) 400KHz Data and specifications subject to change without notice. 200507075-1/18 APU3037 / APU3037A 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 CAUTION: Stresses above those listed in "Absolute Maximum Ratings" may cause permanent damage to the device. PACKAGE INFORMATION 8-PIN PLASTIC TSSOP (O) 8-PIN PLASTIC SOIC (M/MP) Fb 1 Vcc 2 LDrv 3 Gnd 4 8 SS/SD 7 Comp 6 Vc 5 HDrv Fb 1 Vcc 2 LDrv 3 Gnd 4 8 SS/SD 7 Comp 6 Vc 5 HDrv θJA=124°C/W θJA=160°C/W without exposed pad (M) θJA=80°C/W with exposed pad (MP) 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 Fb 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 APU3037 APU3037A 5 > 2 gm 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 3 sR6(C12+C11) [ (1+sR7C11)3[1+sC10(R6+R8)] C123C11 1+sR7 3(1+sR8C10) C12+C11 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 = fS 2 1 2p 3 R7 3 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. The compensation network has three poles and two zeros and they are expressed as follows: C12 = C12 > 50pF If not, change R7 selection. 5) Place R7 in (15) and calculate C10: C10 [ 2p 3 Lo 3 Fo 3 Co VOSC 3 R7 VIN 9/18 APU3037 / APU3037A 6) Place second pole at the ESR zero. FP2 = FESR 1 R8 = 2p 3 C10 3 FP2 Check if R8 > 1 gm 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 C1 C2A, B 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. 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. 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 APU3037A for such application. 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. PGnd PGnd C7A, B L1 Vin 8 7 6 5 Vout L2 Q1 1 2 3 4 DDDC 3215 5 4 C4 6 PGnd R4 C9 7 U1 3 APU3037 2 C3 R5 1 R6 Single Point Analog Gnd Connect to Power Ground plane Analog Gnd C8 8 Analog Gnd Figure 8 - Suggested layout. (Topside shown only) 10/18 APU3037 / APU3037A TYPICAL PERFORMANCE CHARACTERISTICS APU3037A Vcc vs. Icc @470PF, 1150PF and 1540PF Gate Load TA = 258C 14 12 10 8 6 4 2 0 0 2 4 6 Vcc (V) 8 CLOAD =1540pF CLOAD =1150pF Icc (mA) CLOAD =470pF 10 12 14 Figure 9 - Vcc vs. Icc APU3037A Vc vs. Ic @470PF, 1150PF and 1540PF Gate Load TA = 258C 30 25 Ic (ma) 20 15 10 5 0 0 2 4 6 8 10 12 14 16 18 20 22 24 26 Vc (V) Figure 10 - Vc vs. Ic CLOAD =470pF CLOAD =1540pF CLOAD =1150pF 11/18 APU3037 / APU3037A TYPICAL PERFORMANCE CHARACTERISTICS APU3037 Output Voltage 1.3 240 APU3037 Output Frequency 230 1.28 220 Max Max 210 1.26 Kilo Hertz 1.24 190 Volts 200 Min 180 1.22 Min 170 1.2 -40°C 0°C Output Voltage +50°C Spec Max. +100°C Spec Min. +150°C 160 -40°C 0°C +50°C +100°C Spec Max. Spec Min. +150°C Oscillation Frequency Figure 11 - Output Voltage Figure 12 - Output Frequency APU3037 Maximum Duty Cycle 92.0% 90.0% 88.0% Percent Duty Cycle 86.0% 84.0% 82.0% 80.0% -40°C -25°C 0°C +25°C +50°C +75°C +100°C +125°C +150°C Max Duty Cycle Figure 13 - Maximum Duty Cycle 12/18 APU3037 / APU3037A TYPICAL PERFORMANCE CHARACTERISTICS APU3037A Output Voltage 820 460 APU3037A Output Frequency Max 440 810 Max 420 800 400 milli Volts 790 Kilo Hertz 380 Min 780 360 Min 340 770 320 760 -40°C -25°C 0°C +25°C +50°C Spec Max. +75°C +100°C +150°C 300 -40°C -25°C 0°C +25°C +50°C +75°C +100°C +150°C Output Voltage Spec Min. Oscillation Frequency Spec Max. Spec Min. Figure 14 - Output Voltage APU3037 / APU3037A Transconductance ( GM ) Figure 15 - Output Frequency APU3037 / APU3037A Rise Time / Fall Time CL = 1500pF 1000 50 900 45 800 40 700 35 600 nano Seconds micro Mho's 30 500 25 400 20 300 15 200 10 100 5 0 -40°C -25°C 0°C +25°C +50°C Negative load GM +75°C +100°C 0 -40°C -25°C 0°C +25°C Rise Time +50°C Fall time +75°C +100°C Positive load GM Figure 16 - Transconductance Figure 17 - Rise Time and Fall Time 13/18 APU3037 / APU3037A TYPICAL APPLICATION Single Supply 5V Input 5V D1 1N4148 D3 1N4148 D2 1N4148 C4 1uF C5 0.1uF L1 1uH C2 2x 10TPB100ML, 100uF, 55mV C1 47uF Tantalum C3 0.1uF Vcc Vc HDrv Q1 AP60T03GH 1N4148 L2 3.3V @ 4A C7 2x 6TPC150M, 150uF, 40mV SS/SD C8 0.1uF U1 APU3037 LDrv 744311470 4.7uH Q2 AP60T03GH Comp C9 680pF Gnd R4 105K R5 1K, 1% Fb R6 1.65K, 1% Figure 18 - Typical application of APU3037 in an on-board DC-DC converter using a single 5V supply. 14/18 APU3037 / APU3037A TYPICAL APPLICATION Dual Supply, 5V Bus and 12V Bias Input 5V L1 12V 1uH C2 10TPB100M, 100uF, 55m V, 1.5A rms C1 47uF 1.8V/1A APU1206-18 Vcc V c HDrv SS/SD U1 APU3037 C4 0.1uF C1 1uF Q1 AP60T03GH 1N4148 Q2 AP60T03GH R1 C3 47uF L2 3.5uH @ 2.5A C6 6TPB150M, 150uF, 55m V 2.5V/2A C7 0.1uF LDrv C8 2200pF R2 14K Cm op Fb 1K, 1% Gnd R3 1K 1% L2 3.5uH @ 2.5A 5.7uH @ 2.5A C6 6TPB150M, 150uF, 55m V ( Qty 2) 6TPB150M, 150uF, 55m V ( Qty 1) C9 10TPB100M, 100uF, 55m V, 1.5A rms C10 0.1uF C11 1uF Vcc V c HDrv Q3 AP60T03GH 1N4148 Q4 AP60T03GH R4 L3 3.4uH @ 2A C12 6TPB150M, 150uF, 55m V 3.3V/1.8A SS/SD C13 0.1uF U2 APU3037 LDrv Cm op C14 2200pF R5 14K Fb 1.65K, 1% Gnd R6 1K, 1% Figure 19 - Typical application of APU3037 or APU3037A in an on-board DC-DC converter providing the Core, GTL+, and Clock supplies for the Pentium II microprocessor. 15/18 APU3037 / APU3037A TYPICAL APPLICATION 1.8V to 7.5V / 0.5A Boost Converter Vpwr (1.5V Min) L1 1uH Vc/Vcc C1 2x 68uF C5 1uF D1 1N5817 VO U T (7.5V / 0.5A) R1 20K R2 10K Q1 2N2222 R3 20K Q2 2N2222 C10 100pF C4 0.01uF R4 25K C5 0.1uF C9 2x 47uF Q3 AP60T03GH SS/SD Comp Vc U1 HDrv APU3037 Fb Vcc LDrv Gnd C8 1uF Gnd R5 1K, 1% R6 5K, 1% Figure 20 - Typical application of APU3037 as a boost converter. 16/18 APU3037 / APU3037A DEMO-BOARD APPLICATION 5V or 12V to 3.3V @ 10A L1 VIN 5V or 12V 1uH C1 33uF 16V D4 LL4148 C2A 47uF 16V C2B 47uF 16V D2 LL4148 D1 LL4148 Gnd C3 1uF C19 1uF C6 0.1uF L2 Vcc C8 1uF Vc HDrv Q1 AP60T03GH SS/SD C5 0.1uF U1 APU3037 LDrv 1N4148 Q2 AP60T03GH C7 470pF R4 4.7V 3.2uH VOUT 3.3V @ 10A C9B 150uF 6.3V C9C 150uF 6.3V C13 1uF Comp Gnd C4 2200pF R3 20K R6 Gnd Fb 1.65K R5 1K Figure 21 - Demo-board application of APU3037. 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 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# 30V, 12mV, 45A 1 AP60T03GH 30V, 12mV, 45A 1 AP60T03GH Synchronous PWM 1 APU3037 Fast Switching 3 LL4148 1m H, 10A 1 7445601 3.2m H, 12A 1 7443550320 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 2200pF, X7R, 50V 1 ECJ-2VB1H222K 470pF, X7R 1 ECJ-2VB2D471K 1m F, Y5V, 16V 3 ECJ-2VF1C105Z 20K, 5% 1 4.7V, 5% 1 1K, 1% 1 1.65K, 1% 1 Manuf APEC APEC APEC WE WE 17/18 APU3037 / APU3037A DEMO-BOARD WAVEFORMS APU3037 VIN=5.0V, V OUT =3.3V 100 V IN Efficiency (%) 90 V OUT 80 70 0 1 2 3 4 5 6 7 8 9 10 11 Output Current (A) Figure 22 - Efficiency for APU3037 Evaluation Board. Figure 23 - Start-up time @ IOUT=5A. Vss APU3037 APU3037 V OUT IOUT = 5V Figure 24 - Shutdown the output by pulling down the soft-start. Figure 25 - 3.3V output voltage ripple @ IOUT=5A. APU3037 APU3037 2A 4A 0A 0A Figure 26 - Transient response @ IOUT = 0 to 2A. Figure 27 - Transient response @ IOUT = 0 to 4A. 18/18