VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER July 25, 2000 SC1146 TEL:805-498-2111 FAX:805-498-3804 WEB:http://www.semtech.com DESCRIPTION The SC1146 is the latest, high performance, multiphase (PWM) controller designed for high power microprocessors requiring ultra fast transient response. The SC1146 is programmable for the voltage range required by the latest Microprocessors . Utilizing a novel and unique design, the controller distributes the output load across (up to) four converter channels by digitally phase shifting the PWM outputs. This approach greatly reduces the stress and heat on the output stage components while lowering input ripple current by as much as 80%. Accurate current sharing among the four phases is achieved by precision design techniques and trimming of critical elements. The high speed transconductance error amplifier is externally initialized using a soft-start capacitor allowing the controller to “wake-up” without overshoot, thus protecting the low voltage microprocessor loads. The output drive voltage to the power MOSFETs is programmable to minimize switching losses in the drive circuitry. The output voltage is digitally programmable by means of a 5 bit DAC (new codes). A single resistor programs the master clock frequency (8MHz max) or the clock can be supplied by an external source where exact frequency control is desired. The number of operating phases is programmed independently of the external clock. The parts features under-voltage lock-out with hysteresis and over-current protection. FEATURES •= Allows use of small surface mount components •= Ultra fast transient recovery time •= Dramatic reduction of input ripple current and output ripple voltage •= 5-bit programmable DAC for the latest, lower output voltage Microprocessors •= Wide, High frequency operating range •= Selectable 2, 3, 4 phase operation •= +5 Volt only operation eliminates the need for +12V supply •= Precision load current sharing,1%PWM match •= Selectable internal or external clock •= Soft start/UVLO/Over current protection APPLICATIONS •= High end servers and workstations •= High current/Ultra-fast transient microprocessors ORDERING INFORMATION DEVICE (1) PACKAGE TEMP. (TJ) SO-24 0 - 85°C SC1146CSW.TR Note: (1) Only available in tape and reel packaging. A reel contains 1000 devices. BLOCK DIAGRAM PIN CONFIGURATION Top View (24-Pin SOIC) The SC1146 is patent pending © 2000 SEMTECH CORP. Pentium is a registered trademark of Intel Corporation 1 652 MITCHELL ROAD NEWBURY PARK CA 91320 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 ABSOLUTE MAXIMUM RATINGS Parameter Symbol Limits Units VCC5V to GND Vcc5v -0.3 to + 12 V FBG to GND FBG ±1 V VCC2 to GND Vcc2 -0.3 to +20 V Operating Temperature Range TA 0 to +70 °C Junction Temperature Range TJ 0 to +125 °C Storage Temperature Range TSTG -55 to +150 °C Thermal Resistance Junction to Case θJC 25 °C/W Thermal Resistance Junction to Ambient θJA 80 °C/W TLEAD 300 °C Lead Temperature (Soldering) 10 sec ELECTRICAL CHARACTERISTICS Unless otherwise noted: TA = 25°C, VCC 5V = 5V, VCC2 = 5V, 4-Phase operation. PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Supply Voltage Range VCC2 3.9 5.0 15.0 V UVLO Range VCC5V 3.9 5.0 6.0 V UVLO Hystersis VCC5V Supply Voltage Range VCC5V Supply Current VCC2 DRV Outputs open Supply Current VCC5V VOUT = 2.00V, IO = 0 Reference Current Pin Voltage VREF Iref = 250µA VID0-4 Clock Select & Divide VINL Logic Low Select Logic Threshold VINH Logic High VID0-4 Clock Select & Divide IINL Vid0-4 = 0V -20 µA Select Input Bias Current IINH Vid0-4 = 4.5V +50 µA Enable Pin VINL .8 V TBD 4.5 VINH 5.0 mV 5.5 10 V mA 40 2.05 mA V 0.8 2 V V 2 V Maximum Duty Cycle DMAX FB = 0V DRV0-3 Output Voltage VOL Isink = 1mA VOH Isource = 1mA, PWRGOOD = Vcc5v DRV0-3 Source Current ISRC VOUT = 2.00V 40 mA DRV0-3 Sink Current ISNK VOUT = 2.00V 20 mA The SC1146 is patent pending © 2000 SEMTECH CORP. 75 % .3 VCC2-1 V V 2 652 MITCHELL ROAD NEWBURY PARK CA 91320 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 ELECTRICAL CHARACTERISTICS (Cont.) Unless otherwise noted: TA = 25°C, VCC5V = 5V, VCC2 = 5V, 4-Phase operation. PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS Bgout Voltage VBgout Vid = 00000 TBD 1.30 TBD Bgout Impedance RO_Bg External Clock Freq. Range Fext_CK Oscillator Frequency FOSC Internal Clock Freq. Range Fint_CK Match DRV0-3 ∆=D PWM Off Time Toff Overcurrent Comparator, Comparator, Common Mode Range 3 Iref = 250µA Duty cycle (Avg) = 50% OCC_CMR V KΩ .80 8.0 8.5 MHz 7.6 8.0 8.4 MHz .80 8.0 8.5 MHz +1 % 25 % 3 15 V -1 OC+I/P bias Current IB_OC+ Vin = 5V +75 +250 µΑ OC-I/P bias Current IB_OC- Vin = 5V +75 +250 µΑ Input Offset Voltage VOS_OCC Vin = 5V 10 mV Ri_FB VO = 2.00V 12 ΚΩ Feedback Input Impedance Duty Cycle Range D 0 75 % -1 +1 % .05 %/A CONVERTER SPECIFICATIONS, Reference Application Circuit VOUT VID 0-4 = 0000-1111 VCC5V = 5.0V ∆VOUT ∆IO VO = 2.000V IO = 3A - 20A ∆VOUT ∆VIN VCC5V = 5V, VO = 2.000V VIN = 4-6V, (VIN separated from Vcc5v) IO = 5A , Clk = external Ileakage_Off PWRGOOD = Logic High 2 µA ISink_Max PWRGOOD< = .8V 2 mA Power Good Threshold Pwrgood_T_lo Vout = 1.300V - 1.950V +100 mV Voltage Tolerance Pwrgood_T_Hi Vout = 2.000V - 3.500V +150 mV Output Accuracy Over Set Range Load Regulation Line Regulation .025 %/V .15 POWER GOOD SIGNAL Off Leakage Current Power Good Max Sink Current Note: (1) This device is ESD sensitive. Use of standard ESD handling precautions is required. The SC1146 is patent pending © 2000 SEMTECH CORP. 3 652 MITCHELL ROAD NEWBURY PARK CA 91320 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 PIN DESCRIPTION Pin # Pin Name Pin Function 1 VCC 5V Supply voltage input (5V nominal) 2 Divsel Connect to Gnd for four phase operation and to logic High for three Phase operation. 3 Clksel Clock Select: Logic High selects internal clock. Logic Low selects external clock. 4 Extclk External Clock Input. The output frequency is determined by (Clock Input Freq.)/4. Output freq.= (Clock Input)/4. Pull up to Vcc5v to select internal clock. 5 RREF Connects to external reference resistor. Sets the operating frequency of the internal clock and the ramp time for the PWM. Reference voltage at this pin is 2.05V. Trimmed to set 250µA at 8MHz. 6 VID0(1) 7 (1) Programming Input 8 (1) VID2 Programming Input 9 VID3(1) Programming Input VID1 (1) Programming Input (LSB) 10 VID4 Programming Input (MSB) 11 OC+ Over current comparator. Non-Inverting input. 12 OC- Over current comparator. Inverting input. 13 COMP Compensation Pin. Compensation is acheived by connecting a capacitor in series with a resistor between this pin and FBG. A 300K ohm resistor must also be directly connected between this pin and FBG. 14 FB Feedback input connected to supply output. 15 BGOUT Bandgap Reference Output. Output resistance = 3Kohm. Must be bypassed with 4.7nF-100nF capacitor to FBG. This capacitor programs the soft start time. 16 FBG Feedback Ground. This pin must be connected to return side of output caps. This pin is not internally connected to GND. 17 ENABLE Connects to 5V to ENABLE. Connect to GND to disable entire device. 18 GND Ground Pin 19 DRV2 Phase 2 output, output voltage range ~.3V - VCC2 - 1V. 20 DRV0 Phase 0 output, output voltage range ~.3V - VCC2 - 1V. 21 VCC2 Supply voltage for the DRV0-3, may be connected to +5V or +12V supply. There is no Undervoltage Lockout on this pin. 22 DRV1 Phase 1 output, output voltage range ~.3V - VCC2 - 1V. 23 DRV3 Phase 3 output, output voltage range ~.3V - VCC2 - 1V. 24 PWRGOOD Power good should be pulled-up to 5V supply via a 3K - 10K resistor. NOTE: (1) All logic inputs and outputs are open collector TTL compatible. The SC1146 is patent pending © 2000 SEMTECH CORP. 4 652 MITCHELL ROAD NEWBURY PARK CA 91320 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 OUTPUT VOLTAGE Unless specified: 0 = GND; 1 = High (or Floating). TA = 25°C, VCC5V = 5V, VCC2 = 5V, 4-Phase operation. VCCCORE VID4 VID3 VID2 VID1 VID0 (VDC) 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 1 1 1 1 0 0 0 0 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 1 1 0 0 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 1 0 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 1 0 Output Off 1.1 1.125 1.15 1.175 1.2 1.225 1.250 1.275 1.3 1.325 1.35 1.375 1.4 1.425 1.45 1.475 1.5 1.525 1.55 1.575 1.6 1.625 1.65 1.675 1.7 1.725 1.75 1.775 1.8 1.825 1.85 The SC1146 is patent pending © 2000 SEMTECH CORP. 5 652 MITCHELL ROAD NEWBURY PARK CA 91320 10K R33 D1 2 S1 10K 10K 10K 10K .1u .1u 22u,10V C1 7 2 4 6 1 EN 3 Drv3 Divsel Clksel Drv1 23 22 R9 22 22 R8 47pf C16 5 6 Vout/Clk switch 7 8 JMP1 8 3 Rref Drv0 Vid0 Drv2 GND Vid1 Enable Vid2 Vid3 FBG .1u 20 22 R11 19 22 R13 7 2 4 6 1 C23 Vcc2 47pf C26 5 18 Open R15 8 3 16 7 2 4 6 1 12 100 R19 Vid4 Bgout OC+ FB OC- Comp 47pf C37 VOUT 14 SC1146 U2 .1u 10K R20 8 3 7 2 4 6 1 R21 C42 .001 .01 .1 C45 C46 C4 C3 C2 C5 .1u Vcc GND BST TG PRDY DRN EN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND Q2 R3 0 0 11 10 TG PRDY EN DRN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND open R24 C43 .1u 47pf C44 5 C47 Vcc GND .1u 22u,10V C20 22u,10V C21 FDB7030 L3 D6 30BQ015 .1u 11 10 C27 14 10u,16V C28 22u,10V C24 22u,10V C25 FDP6035 Q5 PID1103-1u 22u,10V C29 0 .1u 13 R16 C31 Q6 L5 D7 22u,10V C30 R30 12 9 0 0 FDB7030 22u,10V C33 30BQ015 .1u 11 10 C35 10u,16V C36 R17 22u,10V C34 FDP6035 Q7 PID1103-1u 22u,10V C38 0 BST TG PRDY DRN EN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND 14 .1u C40 R23 Q8 D8 13 R31 12 9 FDB7030 L7 C39 1000uf,6.3 30BQ015 0 0 11 10 * .1 TBD R27 C48 PID1103-1u 0 2.2 ENSYN 22u,10V C17 FDP6035 Q3 Q4 R12 0 SC1405B per 22u,10V C15 30BQ015 C22 R29 12 R25 Freq. set by R22 Freq.=(8.2K/R22)*2Mhz Phase 22u,10V C10 L1 R10 0 14 13 10u,16V C19 R14 BST Vcc GND FDB7030 D5 .1u C18 9 22u,10V C6 C9 R28 12 9 PID1103-1u 0 SC1405B U5 13 1 sel R22 5 C41 TBD R18 C51 1000uf,6.3 0 R26 * R26 AND R27 SET THE OVERVOLTAGE TRIP POINT. C48 SETS THE TIME CONSTANT. R27=0,R26=OPEN to disable OVP_S. Shipped with OVP_S disabled SC1146 BY JUMPERING JMP1, ALL SC1405'S ARE ENABLED AND DISABLED TOGETHER WITH SC1144. THREE OF THE SC1405'S CAN BE DIRECTLY CONTROLLED BY SEPARATING THE TWO ENABLES. (power saving mode) 6 652 MITCHELL ROAD NEWBURY PARK CA 91320 11 15 .1u 10 13 SC1405B U4 17 EN C32 9 Extclk 21 .1u 5 TG PRDY EN DRN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND R2 14 SC1405B U3 EN 4 BST Vcc GND FDP6035 Q1 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER 8 7 6 5 4 3 2 1 D4 .1u C50 VOUT Pwrgood 5v 24 R4 R5 R6 R7 9 10 11 12 13 14 15 16 .1u .1u INPUT 8 3 .1u 3k R32 1 U1 C14 C13 JMP2 Power Good 10uf,6.3v C12 D3 C49 C8 C7 1u,16V 1u,16V 1 2 3 4 5 C11 6 330UF,16V .1u J1 .1u SMOD 10 R1 D2 SS12 SS12 SS12 SS12 July 25, 2000 Long PCB Trace EVALUATION BOARD SCHEMATIC The SC1146 is patent pending © 2000 SEMTECH CORP. +12V VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 BILL OF MATERIAL Item Qty Reference 1 9 C2,C4,C11,C19,C20,C28,C29,C37,C39 2 1 C3 3 9 C5,C12,C14,C17,C18,C21,C22,C26,C27 4 5 C6,C7,C15,C24,C32 5 1 C8 6 3 C16,C25,C33 7 1 8 1 9 Value Manufacturer 1u,10V 10uF, 6.3V X7R, AVX (818)883-7606 Al. Elec.,Murata 22u, 10V Murata (512)250-5082 PN #GRM235Y5V226Z010 1uF, 16V Murata,Al. Elec. 330uF, 16V Nichicon 10u, 16V Murata C40 .01u Murata C42 .022 any 2 C45,C49 .01 Murata,X7R 10 1 C46 .001 Murata 11 4 C50,C51,C52,C53 1nF any 12 1 C54 13 8 D1,D2,D3,D4, D5,D7,D9,D11 1000uF 14 1 J1 15 4 L1,L2,L3,L4 16 4 Q1,Q4,Q7,Q10 IR7811 17 4 Q3,Q6,Q9,Q12 IR3101D2 (Alter.)FDB7030BL SS12(1A) SS32 (3A) Murata,Al. Elec. General Instruments General Instruments INPUT .6uh,12A Falco (305)662-7276 PN #T02508 Int. Rectifier Int. Rectifier Fairchild Semiconductors 18 1 R1 10 Dale,any 19 9 R2,R10,C13,R14,R17,C23,R33,C34,C43 0 any 20 4 R4,R12,R16,R23 1.5 (or zero) any 21 4 R5,R6,R7,R38 10K any 22 4 R8,R9,R11,R13 22 any 23 1 R18 SEL any 23 1 R19 100 any 24 1 R20 2.2k any 25 1 R22 15k any 26 1 R24 300k any 27 5 R25,R40,R41,R42,R43 2.2 any open any 28 1 R26 29 4 R27,R28,R29,R30 30 6 R31,R32,R34,R35,R36,R37 31 1 S1 Vout/Clk switch C&K 32 4 U1,U3,U4,U5 SC1405B/SC1405TS Semtech (805)498-2111 33 1 U2 SC1146CSW 34 1 U6 LM358 51, 1/4W, 1206, 10K Dale TBD(used at light load, any contact factory) (800)cal-swch Semtech (805)498-2111 any Unless otherwise noted, all resistors are 1/10W, 5%, 0805 and all capacitors are 20%, 50v, 0805. The SC1146 is patent pending © 2000 SEMTECH CORP. 7 652 MITCHELL ROAD NEWBURY PARK CA 91320 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 THEORY OF OPERATION ables the PWM controller sequentially. A resistor from RREF pin to FBG programs the frequency and ramp time. FUNCTIONAL DESCRIPTION Clock Freq = (8.2K/Rref) *8Mhz The SC1146 is a programmable, high performance, multi-phase controller designed for the most demanding DC/DC converter applications in which transient response, space, input ripple current and component form factor and cost are paramount. The SC1146 is configured to operate with external MOSFET drivers, such as the SC1405, in high efficiency synchronous applications (See Evaluation Board Schematic). The SC1146 based dc/dc converter consists of four buck converter controllers integrated and synchronized. The high clock frequency allows for smaller inductor values and miniature surface mount, low inductance output capacitors. Since each stage has ¼ the output current, the conduction losses in each stage is reduced by a factor of 1/16. Precision active trimming ensures 1% matching of duty cycles among phases, thus ensuring the heat and component stress is shared equally. The SC1146 may also be configured in asynchronous mode by using buffer transistors. The ramps are then compared to the error amplifier output at the high speed PWM comparator inputs. The controller outputs are buffered versions of the comparator outputs. Fig. 2: The four Gate Drives firing 90° out of phase. VOUT = 1.0V, IOUT = 10A,Vcc2=12V, Asynchronous operation. ERROR AMPLIFIER Fig. 1: VOUT Ripple, VOUT = 1.0V, IOUT = 30A DECODER/BIAS GENERATOR/PWM CONTROLLER The 8 MHz clock is divided down to 2 MHz for four phase operation by the clock decoder. The start of the output pulses are time shifted 90 degrees by the decoder with respect to each other. The Bias Generator generates the ramps to each phase by a precision trimmed current source and on-chip capacitors. The decoder, which is synchronized to the bias generator via the master clock, phase shifts the ramps and en- The SC1146 is patent pending © 2000 SEMTECH CORP. At the heart of the controller is an ultra-fast, transconductance error amplifier. Since the output inductor values can be selected to be a minimum, usually less than a micro-Henry, the delays due to inductor ramp time are minimized during transient load recovery. The higher frequency of operation also allows use of much smaller capacitance on the output. This means that the dc/dc converter output capacitors “hold time” is less. The error amplifier must therefore respond extremely fast “Recover the Fort” after a transient. The SC1146 error amplifier recovers to its normal duty cycle after application of a full load transient within 2 usec maximum, (largely dependant on supply quality) and usually within 1usec. This minimizes undershoot and overshoot during application of a transient. 8 652 MITCHELL ROAD NEWBURY PARK CA 91320 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 ERROR AMPLIFIER CONT. BANDGAP REFERENCE/SOFT START Fig. 3: Transient response, Top trace, Current sense 8A/div @ 30A/usec. Bottom trace, VOUT. The precision internal bandgap reference provides a stable, temperature compensated 2.05 V reference for the error amplifier’s non-inverting input, the DACREF for the VID digital to analog converter, the under-voltage lock-out circuitry as well as the reference for the Bias generator current sources. The error amplifiers noninverting input is connected to the bandgap reference through a 3Kohm resistor, which is also externally connected to a soft-start capacitor via the BGOUT pin. Upon application of power, the non-inverting input of the error amplifier is held low for a short time, set by the RC product of the soft-start capacitor and 3Kohm, allowing for the decoder and PWM controller to settle. This prevents any harmful output voltage overshoots upon start up or after a converter shut-down (as a result of overcurrent or the enable pin pulled low). The non-inverting input then ramps up according to the RC time constant allowing gradual rise of output voltage. OVER-CURRENT COMPARATOR The SC1146 has an internal over-current comparator designed to sense current in the input supply path. The comparator inputs have a high common voltage range thus allowing operation under all possible voltage/current combinations. The output of the comparator pulls the BGOUT (soft start) pin low thus disabling the error amplifier and causing the PWM outputs to enter minimum duty cycle mode, regulating the output at a minimum voltage. A current sense trace may be used as the current sense resistor. This will utilize the trace as input filter inductor, thus preventing conducted emissions to input supply. For details of programming the overcurrent comparator, refer to SC1144-EVB user manual. Fig. 4: Transient response, Top trace, Gate Drive Bottom trace, Transient current 16A/div @ 30A/usec. The error amplifier has two inverting inputs, one for the High Range, (VID4 set to logic high) and one input for the Low Range. The effective gain of the error amplifier stays constant in both ranges keeping the loop gain constant regardless of output voltage range. The SC1146 is patent pending © 2000 SEMTECH CORP. SC1146 Special features: The SC1146 is a special version of the original SC1144, 4-phase PWM controller, with the latest VRM9.0 VID codes which allow programming lower output voltages required by the latest Microprocessors. Also a +12V supply is no longer required. The VCC2 and PWRGOOD pins can be connected to Vcc5v. This eases the connection to “5V-only” MOSFET drivers, such as the SC1405. The DRVs will swing to Vcc5v, eliminating the need for +12V to +5V level shifting. There is no Under-Voltage Lockout on VCC2. 9 652 MITCHELL ROAD NEWBURY PARK CA 91320 VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER SC1146 July 25, 2000 An evaluation board is available which may be ordered directly from the factory. SC1146/1405EVB is a DC/DC converter utilizing the SC1146 four-phase controller in a high current synchronous application. The evaluation board is intended as a guideline for board design, layout and to assess key performance parameters, such as transient response, thermal stress management and input and output ripple considerations. The SC1146EVB includes a DIP switch for mode/voltage selection as well as qualified selection of components for the SC1146 operation. The SC1144EVB user manual contains useful general applications information applicable to SC1146 and may be accessed from our website at www.semtech.com. OUTLINE DRAWING - SO-24 JEDEC MS-013AD B17104B ECN00-1215 The SC1146 is patent pending © 2000 SEMTECH CORP. 10 652 MITCHELL ROAD NEWBURY PARK CA 91320