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Analog Devices Semiconductor Electronic Components Datasheet

ADP3156 Datasheet

Dual Power Supply Controller for Desktop Systems

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ADP3156 pdf
a
Dual Power Supply Controller
for Desktop Systems
ADP3156
FEATURES
Active Voltage Positioning with Gain and Offset
Adjustment
Optimal Compensation for Superior Load Transient
Response
Fixed 1.5 V, 1.8 V and 2.5 V Output Versions
Dual N-Channel Synchronous Driver
On-Board Linear Regulator Controller
Total Output Accuracy ؎1% Over Temperature
High Efficiency, Current-Mode Operation
Short Circuit Protection
Overvoltage Protection Crowbar Protects Loads with
No Additional External Components
Power Good Output
SO-16 Package
APPLICATIONS
Desktop Computer Supplies
ACPI-Compliant Power Systems
General Purpose DC-DC Converters
GENERAL DESCRIPTION
The ADP3156 is a highly efficient synchronous buck switching
regulator controller optimized for converting the 3.3 V or 5 V
main supply into lower supply voltages required on the mother-
boards of Pentium® III and other high performance processor
systems. The ADP3156 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 positioning to enhance load
transient performance. Active voltage positioning results in a
DC/DC converter that provides the best possible transient re-
sponse using 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 ADP3156 provides accurate and reliable short circuit
protection 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
IN OFF
CMPI
VREF +5% VREF –5%
2R
S
Q
R
VT2
VT1
VREF
gm
R
REFERENCE
CT CMPT
OFF-TIME VIN
CONTROL SENSE–
1.20V
ADP3156
VLDO
FB
CMP
The ADP3156 contains a linear regulator controller that is
designed to drive an external N-channel MOSFET. This linear
regulator is used to generate the auxiliary voltages (AGP, GTL,
etc.) required in most motherboard designs, and has been de-
signed to provide a high bandwidth load-transient response. A
pair of external feedback resistors sets the linear regulator out-
put voltage.
VO2
1000F
VCC +12V
22F 1F
R1
35k
20k
R2
SD VCC
DRIVE1
VLDO
ADP3156
CCOMP
200pF
SENSE+
FB
CMP SENSE–
DRIVE2
CT
AGND PGND
VIN +5V
CIN
+
L RSENSE
VO
+
1nF CO
Figure 1. Typical Application
Pentium is a registered trademark of Intel Corporation.
All other trademarks are the property of their respective holders.
REV. 0
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

ADP3156 Datasheet

Dual Power Supply Controller for Desktop Systems

No Preview Available !

ADP3156 pdf
ADP3156–SPECIFICATIONS (0؇C Յ TA Յ +70؇C, VCC = 12 V, VIN = 5 V, unless otherwise noted)1
Parameter
Symbol Conditions
Min Typ Max Units
OUTPUT ACCURACY
ADP3156-1.5 V
ADP3156-1.8 V
ADP3156-2.5 V
VO
1.480 1.500 1.520
1.777 1.800 1.823
2.475 2.500 2.525
V
V
V
OUTPUT VOLTAGE LINE
REGULATION
INPUT DC SUPPLY CURRENT2
Normal Mode
Shutdown
VO ILOAD = 10 A (Figure 2)
VIN = 4.75 V to 5.25 V
IQ VSD = 0.6 V
TA = +25°C, VSD = 2.0 V
0.05
4.1 5.5
140 250
%
mA
µA
CURRENT SENSE THRESHOLD
VOLTAGE
VSENSE(TH) VSENSE– Forced to VOUT – 3% 125 145 165
mV
CT PIN DISCHARGE CURRENT
IT TA = +25°C
VOUT in Regulation
VOUT = 0 V
65
2 10
µA
µA
OFF-TIME
tOFF CT = 150 pF
1.8 2.45 3.2
µs
DRIVER OUTPUT TRANSITION
TIME
tR, tF
CL = 7000 pF (DRIVE1, 2)
TA = +25°C
120 200 ns
POSITIVE POWER GOOD TRIP POINT3
NEGATIVE POWER GOOD TRIP POINT3
VPWRGD
VPWRGD
% Above Output Voltage
% Below Output Voltage
58
–8 –5
%
%
POWER GOOD RESPONSE TIME
tPWRGD
500 µs
CROWBAR TRIP POINT
VCROWBAR % Above Output Voltage
9
15 24
%
ERROR AMPLIFIER
OUTPUT IMPEDANCE
ROERR
275 k
ERROR AMPLIFIER
TRANSCONDUCTANCE
gm(ERR)
2.2 mmho
ERROR AMPLIFIER MINIMUM
OUTPUT VOLTAGE
VCMPMIN
VSENSE– Forced to VOUT + 3%
0.8
V
ERROR AMPLIFIER MAXIMUM
OUTPUT VOLTAGE
VCMPMAX VSENSE– Forced to VOUT – 3%
2.4
V
ERROR AMPLIFIER BANDWIDTH –3 dB BWERR
CMP = Open
500 kHz
LINEAR REGULATOR FEEDBACK
CURRENT
IFB
0.35 1
µA
LINEAR REGULATOR
OUTPUT VOLTAGE
Figure 2, VLDOIN = 1.8 V
VO2
RPROG = 5 k, R2 = 20 k,
1.47 1.5
1.53 V
IO2 = 1 A
SHUTDOWN (SD) PIN
Low Threshold
High Threshold
Input Current
SDL
SDH
SDIC
Part Active
Part in Shutdown
0.6 V
2.0 V
10 µA
NOTES
1All limits at temperature extremes are guaranteed via correlation using standard Statistical Quality Control (SQC) methods. Specifications subject to change without
notice.
2Dynamic supply current is higher due to the gate charge being delivered to the external MOSFETs.
3The trip point is for the output voltage coming into regulation.
Specifications subject to change without notice.
–2– REV. 0


Part Number ADP3156
Description Dual Power Supply Controller for Desktop Systems
Maker Analog Devices
Total Page 12 Pages
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