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Analog Devices Semiconductor Electronic Components Datasheet

ADP3157 Datasheet

5-Bit Programmable Synchronous Controller for Pentium III Processors

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ADP3157 pdf
a
5-Bit Programmable Synchronous
Controller for Pentium® III Processors
ADP3157
FEATURES
Active Voltage Positioning with Gain and Offset
Adjustment
Optimal Compensation for Superior Load Transient
Response
VRM 8.2, VRM 8.3 and VRM 8.4 Compliant
5-Bit Digitally Programmable 1.3 V to 3.5 V Output
Dual N-Channel Synchronous Driver
Total Output Accuracy ؎1% Over Temperature
High Efficiency, Current-Mode Operation
Short Circuit Protection
Overvoltage Protection Crowbar Protects Microprocessors
with No Additional External Components
Power Good Output
SO-16 Package
APPLICATIONS
Desktop PC Power Supplies for:
Pentium II and Pentium III Processor Families
AMD-K6 Processors
VRM Modules
GENERAL DESCRIPTION
The ADP3157 is a highly efficient synchronous buck switching
regulator controller optimized for converting the 5 V main sup-
ply into the core supply voltage required by the Pentium III and
other high performance processors. The ADP3157 uses an
internal 5-bit DAC to read a voltage identification (VID) code
directly from the processor, which is used to set the output
voltage between 1.3 V and 3.5 V. The ADP3157 uses a current
mode, constant off-time architecture to drive two external N-
channel MOSFETs at a programmable switching frequency that
can be optimized for size and efficiency. It also uses a unique
supplemental regulation technique called active voltage position-
ing to enhance load transient performance.
Active voltage positioning results in a dc/dc converter that meets
the stringent output voltage specifications for Pentium II and
Pentium III processors, with the minimum number of output
capacitors and smallest footprint. Unlike voltage-mode and
standard current-mode architectures, active voltage positioning
adjusts the output voltage as a function of the load current so that
it is always optimally positioned for a system transient.
The ADP3157 provides accurate and reliable short circuit pro-
tection and adjustable current limiting. It also includes an
integrated overvoltage crowbar function to protect the micro-
processor from destruction in case the core supply exceeds the
nominal programmed voltage by more than 15%.
FUNCTIONAL BLOCK DIAGRAM
VCC DRIVE1 DRIVE2 PGND AGND PWRGD SENSE+ SENSE–
DELAY
NONOVERLAP
SD
DRIVE
VREF +15%
CROWBAR
2R
IN
VREF +5% VREF –5%
CMPI
S
Q
R
VT1
VREF
R
VT2
gm
REFERENCE
CT CMPT
OFF-TIME
CONTROL
SENSE –
ADP3157
1.20V
DAC
VID0
VID1
VID2
VID3
VID4
CMP
VCC +12V
VIN +5V
22F 1F
VCC
CIN
+
SD DRIVE1
R1
ADP3157
L RSENSE
VO
1.3V TO
SENSE+
CMP
1nF
+ 3.5V
CO
R2 CCOMP
SENSE–
150pF
CT DRIVE2
AGND PGND
VID0–VID4
5-BIT CODE
Figure 1. 5-Bit Code Typical Application
Pentium is a registered trademark of Intel Corporation.
All other trademarks are the property of their respective holders.
REV. A
Information furnished by Analog Devices is believed to be accurate and
reliable. However, no responsibility is assumed by Analog Devices for its
use, nor for any infringements of patents or other rights of third parties
which may result from its use. No license is granted by implication or
otherwise under any patent or patent rights of Analog Devices.
One Technology Way, P.O. Box 9106, Norwood, MA 02062-9106, U.S.A.
Tel: 781/329-4700 World Wide Web Site: http://www.analog.com
Fax: 781/326-8703
© Analog Devices, Inc., 1999


Analog Devices Semiconductor Electronic Components Datasheet

ADP3157 Datasheet

5-Bit Programmable Synchronous Controller for Pentium III Processors

No Preview Available !

ADP3157 pdf
ADP3157–SPECIFICATIONS (0؇C TA +70؇C, VCC = 12 V, VIN = 5 V, unless otherwise noted)1
Parameter
Symbol Conditions
Min Typ Max
OUTPUT ACCURACY
1.3 V Output Voltage
2.0 V Output Voltage
3.5 V Output Voltage
VO (Figure 13)
1.283 1.3
1.980 2.0
3.465 3.5
1.317
2.020
3.535
OUTPUT VOLTAGE LINE
REGULATION
INPUT DC SUPPLY CURRENT2
Normal Mode
Shutdown
CURRENT SENSE THRESHOLD
VOLTAGE
VID0–VID4 THRESHOLD
Low
High
VO ILOAD = 10 A (Figure 2)
VIN = 4.75 V to 5.25 V
0.05
IQ VSD = 0.6 V
TA = +25°C, VID Pins Floating
4.1 5.5
140 250
VSENSE(TH) VSENSE– Forced to VOUT – 3%
VID(TH)
125 145 165
0.6
2.0
VID0–VID4 INPUT CURRENT
VID0–VID4 PULL-UP RESISTANCE
CT PIN DISCHARGE CURRENT
OFF-TIME
DRIVER OUTPUT TRANSITION
TIME
POSITIVE POWER GOOD TRIP POINT3
NEGATIVE POWER GOOD TRIP POINT3
POWER GOOD RESPONSE TIME
CROWBAR TRIP POINT
ERROR AMPLIFIER
OUTPUT IMPEDANCE
ERROR AMPLIFIER
TRANSCONDUCTANCE
ERROR AMPLIFIER MINIMUM
OUTPUT VOLTAGE
ERROR AMPLIFIER MAXIMUM
OUTPUT VOLTAGE
ERROR AMPLIFIER BANDWIDTH –3 dB
SHUTDOWN (SD) PIN
Low Threshold
High Threshold
Input Current
IVID
RVID
I12
tOFF
tR, tF
VPWRGD
VPWRGD
tPWRGD
VCROWBAR
VID = 0 V
TA = +25°C
VOUT in Regulation
VOUT = 0 V
CT = 150 pF
CL = 7000 pF (Drive 1, 2)
TA = +25°C
% Above Output Voltage
% Below Output Voltage
% Above Output Voltage
ROERR
gm(ERR)
VCMPMIN VSENSE+ Forced to VOUT + 3%
VCMPMAX
BWERR
VSENSE+ Forced to VOUT – 3%
CMP = Open
SDL
SDH
SDIC
Part Active
Part in Shutdown
110 220
20 30
65
2 10
1.8 2.45 3.2
120 200
58
–8 –5
500
9 15 24
275
2.2
0.8
2.4
500
2.0
10
0.6
NOTES
1All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods.
2Dynamic supply current is higher due to the gate change being delivered to the external MOSFETs.
3The trip point is for the output voltage coming into regulation.
Specifications subject to change without notice.
Units
V
V
V
%
mA
µA
mV
V
V
µA
k
µA
µA
µs
ns
%
%
µs
%
k
mmho
V
V
kHz
V
V
µA
–2– REV. A


Part Number ADP3157
Description 5-Bit Programmable Synchronous Controller for Pentium III Processors
Maker Analog Devices
Total Page 12 Pages
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