PROGRAMMABLE SYNCHRONOUS DC/DC CONTROLLER FOR ADVANCED PROCESSORS April 28, 1998 SC1152 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION FEATURES The SC1152 is a low-cost, full featured, synchronous voltage-mode controller designed for use in single ended power supply applications where efficiency is of primary concern. Synchronous operation allows for the elimination of heat sinks in many applications. The SC1152 is ideal for implementing DC/DC converters needed to power advanced microprocessors such as ® Pentium ll (Klamath), in both single and multiple processor configurations. Internal level-shift, high-side drive circuitry, and preset shoot-thru control, allows for use of inexpensive n-channel power switches. • • • • • APPLICATIONS • • • • • SC1152 features include an integrated 5-bit VID DAC, temperature compensated voltage reference, triangle wave oscillator, current limit comparator, frequency shift over-current protection, and an accessible, internally compensated error amplifier. Power good signaling, logic compatible shutdown, and over voltage protection are also provided. Pentium® II (Klamath) Core Supply Multiple Microprocessor Supplies Voltage Regulator Modules (VRM) Programmable Power Supplies High Efficiency DC/DC Conversion ORDERING INFORMATION (1) DEVICE PACKAGE TEMP. RANGE (TJ) SO-20 0 - 125°C SC1152CS The SC1152 operates at a fixed 200KHz, providing an optimum compromise between efficiency, external component size, and cost. PIN CONFIGURATION Low cost / full featured Synchronous operation 5 Bit VID DAC programmable output On-chip power good and OVP functions ® Designed to meet Intel VRM8.1 (Pentium II) Note: (1) Add suffix ‘TR’ for tape and reel. BLOCK DIAGRAM Top View VCC CURRENT LIMIT 1.25V REF VCC VID4 VID3 D/A AND SHUTDOWN LOGIC VID2 VID1 SHUTDOWN CS(-) CS(+) + - 70mV BSTH DECODED SHUTDOWN SIGNAL R Q OSCILLATOR UPPER FET LEVEL SHIFT AND DRIVE S VID0 DH PGNDH 200 kHz VOSENSE OPEN COLLECTORS + PWRGOOD - + - + ERROR AMP SHOOT-THRU CONTROL BSTL + SYNCHRONOUS VCC (20-Pin SOIC) FET DRIVE + - DL GND PGNDL OVP GND Pentium is a registered trademark of Intel Corporation © 1998 SEMTECH CORP. 1 652 MITCHELL ROAD NEWBURY PARK CA 91320 PROGRAMMABLE SYNCHRONOUS DC/DC CONTROLLER FOR ADVANCED PROCESSORS SC1152 April 28, 1998 ABSOLUTE MAXIMUM RATINGS Parameter Symbol VIN VCC to GND PGND to GND BST to GND Thermal Resistance θJC Junction to Case Thermal Resistance θJA Junction to Ambient Operating TA Temperature Range Storage TSTG Temperature Range Lead Temperature TLEAD (Soldering) 10 sec Maximum -0.3 to 7 ±1 -0.3 to 15 Units V V V 30 °C/W 90 °C/W 0 to 70 °C -65 to +150 °C 300 °C ELECTRICAL CHARACTERISTICS o Unless specified: VCC = 4.75V to 5.25V; GND = PGND = 0V; FB = VO; 0mV < (CS(+) - CS(-)) < 60mV; TJ = 25 C PARAMETER CONDITIONS Output Voltage IO = 2A Supply Voltage VCC Supply Current VCC = 5.0 Load Regulation MIN (1) TYP MAX UNITS See Table 1. 4.2 (1) IO = 0.3A to 15A (1) 7 V 5 mA 1 % Line Regulation All VID codes 0.5 % Gain (AOL) VOSENSE to VO 35 dB Current Limit Voltage 60 70 80 mV Oscillator Frequency 180 200 220 kHz Oscillator Max Duty Cycle 90 95 % DH Sink/Source Current BSTH - DH = 4.5V, DH - PGNDH = 2V 1 A DL Sink/Source Current BSTL - DL = 4.5V, DL - PGNDL = 2V 1 A OVP Threshold Voltage OVP Source Current 120 VOVP = 3V % 10 Power Good Threshold Voltage 90 Dead Time 50 mA 110 100 % ns NOTE: (1) Specification refers to application circuit (Figure 1.). 2 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 PROGRAMMABLE SYNCHRONOUS DC/DC CONTROLLER FOR ADVANCED PROCESSORS SC1152 April 28, 1998 PIN DESCRIPTION Pin # Pin Name Pin Function 1 GND Small Signal Analog and Digital Ground 2 VCC Chip Supply Voltage 3 OVP High Signal Out if VO > Setpoint + 20% (1) 4 PWRGOOD Open collector logic output, high if VO within 10% of setpoint 5 CS(-) Current Sense Input (negative) 6 CS(+) Current Sense Input (positive) 7 PGNDH Power Ground for High Side Switch 8 DH High Side Driver Output 9 NC Not Connected 10 PGNDL Power Ground for Low Side Switch 11 DL Low Side Driver Output 12 BSTL Vcc for Low Side Driver (Boost) 13 BSTH Vcc for High Side Driver (Boost) (1) 14 SHUTDOWN Logic Low shuts down the converter 15 VOSENSE Top end of internal feedback chain 16 (1) Programming Input (MSB) (1) Programming Input (1) Programming Input (1) Programming Input (1) Programming Input (LSB) 17 18 19 20 VID4 VID3 VID2 VID1 VID0 NOTE: (1) All logic level inputs and outputs are open collector TTL compatible. PIN CONFIGURATION 3 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 PROGRAMMABLE SYNCHRONOUS DC/DC CONTROLLER FOR ADVANCED PROCESSORS SC1152 April 28, 1998 APPLICATION CIRCUIT L1 R1 5mOhm Q1 5V IN C6 1000uF C8 1000uF C10 1000uF VCCP 4 uH + C3 1000uF C1 0.1uF + + R2 10k Q2 C2 1000uF C4 1000uF + + D1 1N5817 + + + + C5 1000uF C7 1000uF C9 1000uF R5 10 C12 0.1uF 12V IN R3 2.32k U1 2 OVP 3 VID0 20 VID1 19 VID2 18 VID3 17 VID4 14 CS(+) OVP CS(-) VID0 VOSENSE VID1 PWRGOOD VID2 VID4 VID3 BSTH SHUTDOWN 1 GND 10 C13 0.1uF VCC PGNDL 9 NC DH PGNDH DL BSTL R4 1.00k C11 6 0.1uF 5 15 4 16 13 8 7 11 12 SC1152CS SHUTDOWN PWRGOOD ® Pentium ll Power Supply Figure 1. MATERIALS LIST Quantity Reference Part/Description Vendor Notes 4 C1,C11-C13 0.1µF Ceramic Various 9 C2-C10 1000µF/6.3V SANYO 1 D1 1N5817 Various 1 L1 4µH 2 Q1, Q2 See notes See notes FET selection requires trade-off between efficiency and cost. Absolute maximum RDS(ON) = 22 mΩ 1 R1 5mΩ IRC OAR-1 Series 1 R2 10kΩ, 5%, 1/8W Various 1 R3 2.32kΩ, 1%, 1/8W Various 1 R4 1kΩ, 1%, 1/8W Various 1 R5 10Ω, 5%, 1/8W Various 1 U1 SC1152CS SEMTECH MV-GX or equiv. Low ESR 8 Turns 16AWG on MICROMETALS T50-52D core 4 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 PROGRAMMABLE SYNCHRONOUS DC/DC CONTROLLER FOR ADVANCED PROCESSORS SC1152 April 28, 1998 OUTPUT VOLTAGE TABLE Unless specified: VCC = 4.75V to 5.25V; GND = PGND = 0V; FB = VO; 0mV < (CS(+) - CS(-)) < 60mV; TJ = 25°C PARAMETER CONDITIONS (1) Output Voltage IO = 2A in Application Circuit (Figure 1) VID 43210 00101 00100 00011 00010 00001 00000 11111 11110 11101 11100 11011 11010 11001 11000 10111 10110 10101 10100 10011 10010 10001 10000 MIN TYP MAX 1.782 1.832 1.881 1.931 1.980 2.030 1.980 2.079 2.178 2.277 2.376 2.475 2.574 2.673 2.772 2.871 2.970 3.069 3.168 3.267 3.366 3.465 1.800 1.850 1.900 1.950 2.000 2.050 2.000 2.100 2.200 2.300 2.400 2.500 2.600 2.700 2.800 2.900 3.000 3.100 3.200 3.300 3.400 3.500 1.818 1.868 1.919 1.969 2.020 2.070 2.020 2.121 2.222 2.323 2.424 2.525 2.626 2.727 2.828 2.929 3.030 3.131 3.232 3.333 3.434 3.535 UNITS V NOTE: (1) All VID codes not specifically listed are invalid and cause shutdown exactly as if the shutdown pin had been asserted. THEORY OF OPERATION The voltage at the VOSENSE pin is applied, through the internal precision resistor feedback chain, to the inverting input of the error amplifier. The non-inverting input of the error amplifier is supplied with a DC voltage derived by the DAC from the internal trimmed bandgap voltage reference. The output of the error amplifier is compared to the triangular output of the internal oscillator to generate a fixed frequency, variable duty cycle pulse train. The internal oscillator uses an on-chip capacitor and precision trimmed current sources to set the frequency to 200 kHz. The generated pulse train is gated with the output of the current limit latch and the inhibit signal to produce a drive signal for the upper FET. It is also inverted to produce a drive signal for the lower FET. These FET drive signals are modified by the “shoot-through control” circuitry so that the top FET turn-on is delayed until the bottom FET has turned off, and visa-versa. The current limit latch is set (ending the upper FET drive pulse early) if the current limit comparator indicates an overcurrent condition. The latch is reset at the start of each oscillator period. The PWRGOOD and OVP signals are derived from the voltage at the VOSENSE pin by comparators fed from the internal feedback chain. 5 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 PROGRAMMABLE SYNCHRONOUS DC/DC CONTROLLER FOR ADVANCED PROCESSORS SC1152 April 28, 1998 CHARACTERISTIC CURVES SC1152 Efficiency in Application Circuit (Figure 1). 95.0% 90.0% 3.50 Volts 3.00 Volts 85.0% 2.50 Volts 2.00 Volts Efficiency 1.80 Volts 80.0% 75.0% 70.0% 0.000 2.000 4.000 6.000 8.000 10.000 12.000 14.000 16.000 Output Current (Amps) SC1152 Regulation in Application Circuit (Figure 1). 0.000 -0.005 Delta 1.8 -0.010 Delta 3.5 Vout (V) ∆ -0.015 Delta 2.0 -0.020 Delta 2.5 Delta 3.0 -0.025 0.000 2.000 4.000 6.000 8.000 10.000 12.000 14.000 16.000 Output Current (Amps) 6 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320 PROGRAMMABLE SYNCHRONOUS DC/DC CONTROLLER FOR ADVANCED PROCESSORS SC1152 April 28, 1998 OUTLINE DRAWING SO-20 Ref. MS-013AC 7 © 1998 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320