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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 out*= 5-bit programmable DAC for the latest, lower *= Wide, High frequency operating range *= Selectable 2, 3, 4 phase operation *= +5 Volt only operation eliminates the need for *= 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)
put ripple voltage
output voltage Microprocessors
+12V supply
PACKAGE SO-24
TEMP. (TJ) 0 - 85C
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
Pentium is a registered trademark of Intel Corporation
1
(c) 2000 SEMTECH CORP.
652 MITCHELL ROAD NEWBURY PARK CA 91320
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
SC1146
ABSOLUTE MAXIMUM RATINGS
Parameter VCC5V to GND FBG to GND VCC2 to GND Operating Temperature Range Junction Temperature Range Storage Temperature Range Thermal Resistance Junction to Case Thermal Resistance Junction to Ambient Lead Temperature (Soldering) 10 sec Symbol Vcc5v FBG Vcc2 TA TJ TSTG JC JA TLEAD Limits -0.3 to + 12 1 -0.3 to +20 0 to +70 0 to +125 -55 to +150 25 80 300 Units V V V C C C C/W C/W C
ELECTRICAL CHARACTERISTICS
Unless otherwise noted: TA = 25C, VCC 5V = 5V, VCC2 = 5V, 4-Phase operation. PARAMETER Supply Voltage Range UVLO Range UVLO Hystersis SYMBOL VCC2 VCC5V VCC5V CONDITIONS MIN 3.9 3.9 TYP 5.0 5.0 TBD MAX 15.0 6.0 UNITS V V mV
Supply Voltage Range Supply Current Supply Current Reference Current Pin Voltage VID0-4 Clock Select & Divide Select Logic Threshold VID0-4 Clock Select & Divide Select Input Bias Current Enable Pin
VCC5V VCC2 VCC5V VREF VINL VINH IINL IINH VINL VINH DRV Outputs open VOUT = 2.00V, IO = 0 Iref = 250A Logic Low Logic High Vid0-4 = 0V Vid0-4 = 4.5V
4.5
5.0 10
5.5
V mA
40 2.05 0.8 2 -20 +50 .8 2
mA V V V A A V V
Maximum Duty Cycle DRV0-3 Output Voltage
DMAX VOL VOH ISRC ISNK
FB = 0V Isink = 1mA Isource = 1mA, PWRGOOD = Vcc5v VOUT = 2.00V VOUT = 2.00V VCC2-1
75 .3
% V V
DRV0-3 Source Current DRV0-3 Sink Current
40 20
mA mA
The SC1146 is patent pending
2 652 MITCHELL ROAD NEWBURY PARK CA 91320
(c) 2000 SEMTECH CORP.
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
SC1146
ELECTRICAL CHARACTERISTICS (Cont.)
Unless otherwise noted: TA = 25C, VCC5V = 5V, VCC2 = 5V, 4-Phase operation. PARAMETER Bgout Voltage Bgout Impedance External Clock Freq. Range Oscillator Frequency Internal Clock Freq. Range Match DRV0-3 PWM Off Time SYMBOL VBgout RO_Bg Fext_CK FOSC Fint_CK =D Toff Duty cycle (Avg) = 50% Iref = 250A .80 7.6 .80 -1 CONDITIONS Vid = 00000 MIN TBD TYP 1.30 3 8.0 8.0 8.0 8.5 8.4 8.5 +1 25 MAX UNITS TBD V K MHz MHz MHz % %
Overcurrent Comparator, Comparator, Common Mode Range OC+I/P bias Current OC-I/P bias Current Input Offset Voltage Feedback Input Impedance Duty Cycle Range
OCC_CMR
3
15
V
IB_OC+ IB_OCVOS_OCC Ri_FB D
Vin = 5V Vin = 5V Vin = 5V VO = 2.00V
+75 +75 10 12 0
+250 +250
mV
75
%
CONVERTER SPECIFICATIONS, Reference Application Circuit Output Accuracy Over Set Range Load Regulation Line Regulation VOUT
VOUT IO VOUT VIN
VID 0-4 = 0000-1111 VCC5V = 5.0V VO = 2.000V IO = 3A - 20A VCC5V = 5V, VO = 2.000V VIN = 4-6V, (VIN separated from Vcc5v) IO = 5A , Clk = external PWRGOOD = Logic High PWRGOOD< = .8V Vout = 1.300V - 1.950V Vout = 2.000V - 3.500V
-1 .025
+1 .05
% %/A %/V
.15
POWER GOOD SIGNAL Off Leakage Current Power Good Max Sink Current Power Good Threshold Voltage Tolerance Ileakage_Off ISink_Max Pwrgood_T_lo Pwrgood_T_Hi 2 2 +100 +150 A mA mV mV
Note: (1) This device is ESD sensitive. Use of standard ESD handling precautions is required.
The SC1146 is patent pending
3 652 MITCHELL ROAD NEWBURY PARK CA 91320
(c) 2000 SEMTECH CORP.
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
SC1146
PIN DESCRIPTION
Pin # 1 2 3 4 VCC 5V Divsel Clksel Extclk Pin Name Pin Function Supply voltage input (5V nominal) Connect to Gnd for four phase operation and to logic High for three Phase operation. Clock Select: Logic High selects internal clock. Logic Low selects external clock. 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. 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 250A at 8MHz. Programming Input (LSB) Programming Input Programming Input Programming Input Programming Input (MSB) Over current comparator. Non-Inverting input. Over current comparator. Inverting input. 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. Feedback input connected to supply output. Bandgap Reference Output. Output resistance = 3Kohm. Must be bypassed with 4.7nF-100nF capacitor to FBG. This capacitor programs the soft start time. Feedback Ground. This pin must be connected to return side of output caps. This pin is not internally connected to GND. Connects to 5V to ENABLE. Connect to GND to disable entire device. Ground Pin Phase 2 output, output voltage range ~.3V - VCC2 - 1V. Phase 0 output, output voltage range ~.3V - VCC2 - 1V. Supply voltage for the DRV0-3, may be connected to +5V or +12V supply. There is no Undervoltage Lockout on this pin. Phase 1 output, output voltage range ~.3V - VCC2 - 1V. Phase 3 output, output voltage range ~.3V - VCC2 - 1V. Power good should be pulled-up to 5V supply via a 3K - 10K resistor.
(1) (1)
5
RREF
6 7 8 9 10 11 12 13
VID0(1) VID1 VID2
VID3(1) VID4 OC+ OCCOMP
(1)
14 15
FB BGOUT
16 17 18 19 20 21 22 23 24
FBG ENABLE GND DRV2 DRV0 VCC2 DRV1 DRV3 PWRGOOD
NOTE: (1) All logic inputs and outputs are open collector TTL compatible. 4 652 MITCHELL ROAD NEWBURY PARK CA 91320
The SC1146 is patent pending
(c) 2000 SEMTECH CORP.
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
SC1146
OUTPUT VOLTAGE
Unless specified: 0 = GND; 1 = High (or Floating). TA = 25C, VCC5V = 5V, VCC2 = 5V, 4-Phase operation.
VCCCORE VID2 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 VID1 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 VID0 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 (VDC) 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
VID4 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
VID3 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
The SC1146 is patent pending
5 652 MITCHELL ROAD NEWBURY PARK CA 91320
(c) 2000 SEMTECH CORP.
Extclk
Vcc2
.1u
VOUT
Rref
Drv0
C23
.1u
10
Vid4
Bgout
15 47pf C37
C32
sel R22
C42 .001 .01 C45 .1 C46 R25 open R24 C43 .1u C47
C41
SC1146 U2
.1u
10K R20
.1u
(c) 2000 SEMTECH CORP. 652 MITCHELL ROAD NEWBURY PARK CA 91320
C14
1 2 3 4 5 C11 6 INPUT
330UF,16V
1u,16V
1u,16V
C7
10uf,6.3v
3k R32 1 R4 R5 R6 R7 2 5v Pwrgood 24
.1u
The SC1146 is patent pending
EVALUATION BOARD SCHEMATIC
July 25, 2000
+12V
Long PCB Trace
10K R33 10 R1 J1
D1
D2
D3
D4 .1u C50
SMOD
.1u .1u .1u .1u
SS12 SS12 SS12 SS12 .1u C49 22u,10V C1 R2 .1u R28 12 9 11 10 0 .1u C18 10u,16V C19 R10 0 C22 R29 12 9 11 10 0 .1u C27 10u,16V C28 R14 14 .1u 13 R30 12 9 11 10 0 .1u C35 10u,16V C36 R17 0 14 .1u C40 13 R31 12 9 11 10 0 0 C51 1000uf,6.3 FDB7030 30BQ015 R23 Q8 D8 L7 C39 1000uf,6.3 FDP6035 Q7 PID1103-1u 22u,10V C34 22u,10V C38 0 FDB7030 30BQ015 22u,10V C33 C31 R16 Q6 D7 L5 0 22u,10V C30 FDP6035 Q5 PID1103-1u R12 0 Q4 FDB7030 D6 30BQ015 L3 22u,10V C17 FDP6035 Q3 PID1103-1u 22u,10V C20 22u,10V C21 22u,10V C24 22u,10V C25 22u,10V C29 R3 0 C9 Q2 FDB7030 D5 30BQ015 L1 0 22u,10V C10 22u,10V C15 FDP6035 Q1 PID1103-1u 22u,10V C6
.1u
C2
C3
C4
Power Good
8 3
Vcc GND
BST
14 13
C12
C13
EN
7 2 4 6 1 5
S1 9 10 11 12 13 14 15 16 8 7 6 5 4 3 2 1
10K 10K 10K 10K 3 EN 4
Divsel
Drv3
23
22 R9 22 R8
47pf C16
TG PRDY EN DRN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND SC1405B U3
Clksel
Drv1
22
21
8 3 7 2 4 6 1 47pf C26 5
Vcc GND
BST
14 .1u 13
5
20
22 R11 22 R13
6 Vout/Clk switch 7
Vid0
Drv2
19
Vid1
GND
18
TG PRDY DRN EN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND SC1405B U4
C5
C8
JMP2
U1
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
8 JMP1 9
Vid2
Enable
17 EN Open R15 16
8 3 7 2 4 6 1 5
Vcc GND
BST TG
Vid3
FBG
11
OC+
FB
14
VOUT
PRDY EN DRN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND SC1405B U5
12 TBD R18 100 R19
OC-
Comp
13 1 R21 8 3 7 2 4 6 1 47pf C44 5
Vcc GND
BST TG
PRDY DRN EN CO DELAY_C BG OVP_S DSPS_DR S_MOD PGND SC1405B
Freq. set by R22 Freq.=(8.2K/R22)*2Mhz Phase
ENSYN
per
2.2
*
.1 TBD R27 C48
0 R26
* 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) 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
6
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
BILL OF MATERIAL Item Qty 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 23 24 25 26 27 28 29 30 31 32 33 34 9 1 9 5 1 3 1 1 2 1 4 1 8 1 4 4 4 1 9 4 4 4 1 1 1 1 1 5 1 4 6 1 4 1 1 Reference C2,C4,C11,C19,C20,C28,C29,C37,C39 C3 C5,C12,C14,C17,C18,C21,C22,C26,C27 C6,C7,C15,C24,C32 C8 C16,C25,C33 C40 C42 C45,C49 C46 C50,C51,C52,C53 C54 D1,D2,D3,D4, D5,D7,D9,D11 J1 L1,L2,L3,L4 Q1,Q4,Q7,Q10 Q3,Q6,Q9,Q12 R1 R2,R10,C13,R14,R17,C23,R33,C34,C43 R4,R12,R16,R23 R5,R6,R7,R38 R8,R9,R11,R13 R18 R19 R20 R22 R24 R25,R40,R41,R42,R43 R26 R27,R28,R29,R30 R31,R32,R34,R35,R36,R37 S1 U1,U3,U4,U5 U2 U6 Value 1u,10V 10uF, 6.3V 22u, 10V 1uF, 16V 330uF, 16V 10u, 16V .01u .022 .01 .001 1nF 1000uF SS12(1A) SS32 (3A) INPUT .6uh,12A IR7811 IR3101D2 (Alter.)FDB7030BL 10 0 1.5 (or zero) 10K 22 SEL 100 2.2k 15k 300k 2.2 open Manufacturer
SC1146
X7R, AVX (818)883-7606 Al. Elec.,Murata Murata (512)250-5082 PN #GRM235Y5V226Z010 Murata,Al. Elec. Nichicon Murata Murata any Murata,X7R Murata any Murata,Al. Elec. General Instruments General Instruments
Falco (305)662-7276 PN #T02508 Int. Rectifier Int. Rectifier Fairchild Semiconductors Dale,any any any any any any any any any any any any
51, 1/4W, 1206, 10K Dale TBD(used at light load, any contact factory) Vout/Clk switch C&K SC1146CSW LM358 (800)cal-swch Semtech (805)498-2111 any SC1405B/SC1405TS Semtech (805)498-2111
Unless otherwise noted, all resistors are 1/10W, 5%, 0805 and all capacitors are 20%, 50v, 0805.
The SC1146 is patent pending
7 652 MITCHELL ROAD NEWBURY PARK CA 91320
(c) 2000 SEMTECH CORP.
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
SC1146
THEORY OF OPERATION
FUNCTIONAL DESCRIPTION
ables the PWM controller sequentially. A resistor from RREF pin to FBG programs the frequency and ramp time. 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 1/4 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 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.
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
8 652 MITCHELL ROAD NEWBURY PARK CA 91320
(c) 2000 SEMTECH CORP.
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000 ERROR AMPLIFIER CONT. BANDGAP REFERENCE/SOFT START
SC1146
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.
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.
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
9 652 MITCHELL ROAD NEWBURY PARK CA 91320
(c) 2000 SEMTECH CORP.
VRM9.0 PROGRAMMABLE, MULTI-PHASE, HIGH PERFORMANCE PWM CONTROLLER
July 25, 2000
SC1146
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
10 652 MITCHELL ROAD NEWBURY PARK CA 91320
(c) 2000 SEMTECH CORP.

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