Si9142
Vishay Siliconix
Synchronous Buck Controller for High Performance Processors
FEATURES
D
D
D
D
D
Over-Voltage Protection
Programmable Over-Current Protection
Voltage Mode Control
Precision 1.3-V,
"1.6%
Reference
Drives N-Channel Switch and Rectifier
D
D
D
D
D
800-mA Quiescent Current (f
s
= 200 kHz)
150-mA 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 both standard and lead (Pb)-free 20-pin
SOIC wide-body packages and specified to operate over the
commercial (0_ to 70_C) temperature range.
A demo board, Si9142DB, is available.
FUNCTIONAL BLOCK DIAGRAM
V
CC
Regulator
V
L(out)
NI
FB
COMP
SYNC
R
OSC
V
L(in)
SS/ENABLE
FB
R
S
S R
Oscillator
Error Amp
+
−
+
−
V
L(in)
PWM Comp
IN
V
L(out)
Reference
V
L(in)
V
REF
REF
BST
D
H
LX
Driver
V
L(out)
D
L
PGND
Logic
Control
and
EN BBM
+
OCP
−
I
CS
170
mA
AGND
NI +17%
−
OVP
+
+
V
CC
UVLO
PWR_GOOD
NI
−12%
−
NI +12%
+
−
Document Number: 70750
S-40809—Rev. D, 26-Apr-04
www.vishay.com
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
Q
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 kW (100 kHz) to 10 kW (1 MHz)
V
L(out), (in)
Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 4.7
mF
V
L(out)
Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
v1
mA
V
REF
Capacitance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0.1
mF
V
REF
Load . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .
v1
mA
Analog and Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to V
L
SPECIFICATIONS
Specific Test Conditions
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
Limits
T
A
= 0 to 70_C
V
CC
= 4.75 V t 13.2 V
4 75 to 13 2
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
mA
I
OL
= 500
mA
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
mA
V
L
Output Voltage
Line Rejection
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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
Document Number: 70750
S-40809—Rev. D, 26-Apr-04
2
Si9142
Vishay Siliconix
SPECIFICATIONS
Specific Test Conditions
Parameter
SS/Enable
Source Current
Fault Sink Current
Logic Low
Logic High
2.4
−2.5
20
−5
35
0.8
−7.5
mA
mA
V
Limits
T
A
= 0 to 70_C
V
CC
= 4.75 V to 13.2 V
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
mA
mV
mA
PWR_GOOD
V
PWR_GOOD
High
V
PWR_GOOD
Low
Output Sink Current
Typical Hysteresis = 1%
V
NI
= V
REF
V
DS
v
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
V
NI
+ 12%
V
NI
+ 17%
V
NI
+ 22%
V
OCP
I
CS
Sink Current
4.75
v
V
ICS
v
13.2 V
126
170
204
mA
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.
Document Number: 70750
S-40809—Rev. D, 26-Apr-04
www.vishay.com
3
Si9142
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS OTHERWISE NOTED)
1.315
1.310
1.305
VREF (V)
1.300
1.295
1.290
1.285
4
6
8
10
12
14
V
DD
−
Supply Voltage (V)
V REF (V)
V
REF
vs. Supply Voltage
1.315
1.310
1.305
1.300
1.295
1.290
1.285
0.0
V
REF
vs. Load Current
0.2
0.4
0.6
0.8
1.0
Load (mA)
Supply Current vs. Supply Voltage
0.75
80
60
Error Amplifier Gain and Phase
0
Gain
−30
Phase (deg)
Phase
−60
−90
−120
Normal Current (mA)
0.73
Gain (dB)
40
20
0
0.71
0.69
−20
0.67
4.75
6.75
8.75
V
DD
−
Supply (V)
10.75
12.75
−40
0.0001
0.001
0.01
0.1
1
10
100
f
−
Frequency (MHz)
−150
98
96
D
MAX
vs. Switching Frequency
1200
Oscillator Frequency vs. R
OSC
Switching Frequency (kHz)
94
D MAX (%)
92
90
88
86
84
82
0
300
600
900
1200
Switching Frequency (kHz)
900
600
300
0
0
10
20
30
40
50
R
OSC
(kW)
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4
Document Number: 70750
S-40809—Rev. D, 26-Apr-04
Si9142
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS OTHERWISE NOTED)
DH I
SOURCE
vs. Voltage
Between BST and LX
DH I
SINK
vs. Voltage
Between BST and LX
−400
−600
−800
DH I SOURCE (mA)
1400
1350
1300
DH I SINK (mA)
1250
1200
1150
1100
1050
1000
4.5
−1000
−1200
−1400
−1600
−1800
−2000
4.5
5.0
5.5
6.0
6.5
5.0
5.5
6.0
6.5
Voltage Between BST and LX (V)
Voltage Between BST and LX (V)
−400
−600
DL I SOURCE (mA)
−800
−1000
−1200
−1400
−1600
−1800
4.5
DL I
SOURCE
vs. V
L
1700
1600
1500
DL I SINK (mA)
1400
1300
1200
1100
1000
4.5
DL I
SINK
vs. V
L
5.0
5.5
V
L
(V)
6.0
6.5
5.0
5.5
V
L
(V)
6.0
6.5
184
182
180
178
I CS (
m
A)
I
CS
vs. Supply Voltage
173
172
171
170
I CS (
m
A)
169
168
167
166
165
I
CS
vs. Temperature
176
174
172
170
168
166
4.75
6.75
8.75
10.75
12.75
0
20
40
60
80
100
V
DD
−
Supply Voltage (V)
Document Number: 70750
S-40809—Rev. D, 26-Apr-04
Temperature (C)
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