Si9142
Vishay Siliconix
Si9142
Synchronous Buck Controller for High Performance Processors
FEATURES
•
•
•
•
•
Over-Voltage Protection
Programmable Over-Current Protection
Voltage Mode Control
Precision 1.3-V, ±1.6% Reference
Drives N-Channel Switch and Rectifier
•
•
•
•
•
800-µA Quiescent Current (f
s
= 200 kHz)
150-µA Standby Current
Integrated “Power Good” Output
Synchronization
Under-Voltage Lockout
DESCRIPTION
The voltage mode, synchronous buck controller is designed
for point-of-use dc/dc conversion in high performance server
and desktop computers. High efficiency is accomplished at full
load by driving high- and low-side n-channel MOSFETs. The
input voltage range has been designed for 4.75 V to 13.2 V to
allow use of either 5 V or 12 V. The 1-MHz switching
frequency combined with the 10-MHz error amplifier provides
ultra-fast transient response necessary in a high performance
microprocessor power supply.
Si9142 is available in a 20-pin SOIC wide-body package and
specified to operate over the commercial (0° to 70°C)
temperature range.
A demo board, Si9142DB, is available.
FUNCTIONAL BLOCK DIAGRAM
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www.siliconix.com
S-60752—Rev. C, 05-Apr-99
1
Si9142
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
Voltages Referenced to AGND
V
SYNC_IN
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 7 V
V
SYNC_OUT
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 7 V
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 15 V
Voltages Referenced to PGND
V
BST
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . -0.3 to 20 V
V
PGND
to V
AGND
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ±2 V
V
L
Short to GND . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
V
REF(OUT)
Short to GND. . . . . . . . . . . . . . . . . . . . . . . . . . Continuous
Continuous Power Dissipation (T
A
= 25°C)
a
20-Pin SOIC Wide-Body
b
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1.45 W
Operating Temperature Range. . . . . . . . . . . . . . . . . . . . . . . 0 to 70°C
Storage Temperature Range . . . . . . . . . . . . . . . . . . . . . . -65 to 125°C
Lead Temperature (soldering, 10 sec) . . . . . . . . . . . . . . . . . . . . 300°C
T
JMAX
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150°C
Θ
JA
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .86°C/W
Notes
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 11.6 mW/°C above 25°C.
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to absolute
maximum rating conditions for extended periods may affect device reliability.
RECOMMENDED OPERATING CONDITIONS
V
CC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4.75 V to 13.2 V
R
OSC
. . . . . . . . . . . . . . . . . . . . . . 100 kΩ (100 kHz) to 10 kΩ (1 MHz)
V
L(out), (in)
Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7
µF
V
L(out)
Load
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≤1
mA
V
REF
Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1
µF
V
REF
Load
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . ≤1
mA
Analog and Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to V
L
SPECIFICATIONS
Limits
Test Conditions
Unless Otherwise Specifed
Parameter
Reference
Output Voltage
Regulation
Line Rejection
I
REF
= 0
I
REF
= 0 to 1 mA
At 10 kHz
1.30 -1.6%
-10
80
1.30
1.30 +1.6%
10
V
mV
dB
V
CC
= 4.75 V to 13.2 V
T
A
= 0 to 70°C
Min
a
Typ
b
Max
a
Unit
Oscillator
Operating Frequency
PWM Maximum Duty Cycle
SYNC High
SYNC Low
Sync = Open
f
OSC
= 200 kHz
f
OSC
= 400 kHz
I
OH
= -100
µA
I
OL
= 500
µA
100
94
88
0.7 V
L
0.3 V
L
1000
kHz
%
V
Output Drivers
Source/Sink I (Peak)
BST - LX = 4.5 V
V
CC
= 4.75 V
H Driver
L Driver
500
500
1000
1000
mA
Supply
Quiescent Current PWM
Standby Current Shutdown
f
osc
= 200 kHz
V
CC
< 3.5 V
800
150
1200
225
µA
V
L
Output Voltage
Line Rejection
I
VL
= 0, V
CC
= 5.7 to 13.2 V
I
VL
= 0, V
CC
= 4.7 to 5.7 V
At 10 kHz
4.95
5.7
V
IN
- 0.2 V
30
6.05
V
dB
S-60752—Rev. C, 05-Apr-99
2
FaxBack 408-970-5600, request 70750
www.siliconix.com
Si9142
Vishay Siliconix
SPECIFICATIONS
Limits
Test Conditions
Unless Otherwise Specifed
Parameter
SS/Enable
Source Current
Fault Sink Current
Logic Low
Logic High
2.4
-2.5
20
-5
35
0.8
-7.5
µA
mA
V
V
CC
= 4.75 V to 13.2 V
T
A
= 0 to 70°C
Min
a
Typ
b
Max
a
Unit
UVLO
Lockout Voltage
Hysteresis
V
L
Falling
3.6
200
3.8
V
mV
Error Amplifier
Unity-Gain BW Product
Input Bias Current
Offset Voltage
Output Current
V
CC
= 5 V
V
NI
= V
REF
, V
FB
= 1.0 V
V
NI
= V
REF
Source (V
FB
= 0.8 V, NI = V
REF
)
Sink (V
FB
= 2.4 V, NI = V
REF)
0.8
-1
-15.0
10
0
0
1
15.0
-1
MHz
µA
mV
mA
PWR_GOOD
V
PWR_GOOD
High
V
PWR_GOOD
Low
Output Sink Current
Typical Hysteresis = 1%
V
NI
= V
REF
V
DS
≤
1 V
V
NI
+ 7%
V
NI
- 17%
2
V
NI
+12%
V
NI
-12%
V
NI
+ 17%
V
NI
- 7%
V
mA
OVP
Threshold Voltage
V
NI
= V
REF
BST - L
X
= 4.5 V
4.75
≤
V
ICS
≤
13.2 V
V
NI
+ 12%
V
NI
+ 17%
V
NI
+ 22%
V
OCP
I
CS
Sink Current
Notes
a. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum.
b. Typical values are for DESIGN AID ONLY, not guaranteed nor subject to production testing.
126
170
204
µA
FaxBack 408-970-5600, request 70750
www.siliconix.com
S-60752—Rev. C, 05-Apr-99
3
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