SI9140CY-T1 [VISHAY]
MP Controller For High Performance Process Power Supplies;
| 型号： | SI9140CY-T1 |
| 厂家： | 
VISHAY |
| 描述： | MP Controller For High Performance Process Power Supplies CD 开关 光电二极管 |
| 文件： | 总19页 (文件大小：238K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Si9140
Vishay Siliconix
MP Controller For High Performance Process Power Supplies
FEATURES
D Runs on 3.3- or 5-V Supplies
D High Frequency Operation (>1 MHz) D Full Set of Protection Circuitry
D Adjustable, High Precision Output
D High Efficiency Synchronous
D 2000-V ESD Rating (Si9140CQ/DQ)
Voltage
Switching
DESCRIPTION
Siliconix’ Si9140 Buck converter IC is a high-performance,
surface-mount switchmode controller made to power the new
generation of low-voltage, high-performance micro-
processors. The Si9140 has an input voltage range of 3 to
6.5 V to simplify power supply designs in desktop PCs. Its
high-frequency switching capability and wide bandwidth
feedback loop provide tight, absolute static and transient load
regulation. Circuits using the Si9140 can be implemented with
low-profile, inexpensive inductors, and will dramatically
minimize power supply output and processor decoupling
capacitance. The Si9140 is designed to meet the stringent
regulation requirements of new and future high-frequency
microprocessors, while improving the overall efficiency in new
“green” systems.
down. These simultaneous changes have made dedicated,
high-frequency, point-of-use buck converters an essential part
of any system design. These point-of-use converters must
operate at higher frequencies and provide wider feedback
bandwidths than existing converters, which typically operate
at less than 250 kHz and have feedback bandwidths of less
than 50 kHz. The Si9140’s 100-kHz feedback loop bandwidth
ensures a minimum improvement of one-half the required
output/decoupling capacitance, resulting in a tremendous
reduction in board size and cost of implementation.
With the microprocessing power of any PC representing an
investment of hundreds of dollars, designers need to ensure
that the reliable operation of the processor will not be affected
by the power supply. The Si9140 provides this assurance. A
demo board, the Si9140DB, is available.
Today’s state-of-the-art microprocessors run at frequencies
over 100 MHz. Processor clock speeds are going up and so
are current requirements, but operating voltages are going
Si9140CQ-T1 and Si9140DQ-T1 are available in lead free.
APPLICATION CIRCUIT
V
IN
V
CCP
R3
C3
L1
2 x Si4435DY
+
V
OUT
R1
R2
C1
+
2 x Si4410DY
D1
Power-Good
U1
R4
C2
Si9140
C4
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
V
V
DD
S
R7
MON
DR
C8
R13
C5
R5
V
D
S
GOOD
PGND
COMP
FB
UVLO
SET
R10
0.1%
C
R
NI
OSC
R6
C9
V
REF
OSC
R12
0.1%
ENABLE
C6
C7
GND
R8
R9
C10
R11
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
1
Si9140
Vishay Siliconix
ABSOLUTE MAXIMUM RATINGS
Voltages Referenced to GND.
V
P
V
, V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 8 V
S
DD
Thermal Impedance (QJA
)
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . "0.3 V
GND
16-Pin SOIC (Y Suffix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 140_C/W
to V . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V
16-Pin TSSOP (Q Suffix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 135_C/W
DD
S
Linear Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to V +0.3 V
DD
Operating Temperature
Logic Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −0.3 V to V +0.3 V
DD
C Suffix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0_ to 70_C
Peak Output Drive Current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 350 mA
Storage Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −65 to 150_C
Operating Junction Temperature . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 150_C
Power Dissipation (Package)a
D Suffix . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . −40_ to 85_C
Notes
a. Device mounted with all leads soldered or welded to PC board.
b. Derate 7.2 mW/_C above 25_C.
c. Derate 7.4 mW/_C above 25_C.
\b
16-Pin SOIC (Y Suffix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 900 mW
c
16-Pin TSSOP (Q Suffix) . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 925 mW
* . Exposure to Absolute Maximum rating conditions for extended periods may affect device reliability. Stresses above Absolute Maximum rating may cause permanent
damage. Functional operation at conditions other than the operating conditions specified is not implied. Only one Absolute Maximum rating should be applied at any
one time
RECOMMENDED OPERATING RANGE
Voltages Referenced to GND.
V
V
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 V to 6.5 V
C
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 47 pF to 200 pF
DD
OSC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 3 V to 6.5 V
Linear Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to V
Digital Inputs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 0 to V
S
DD
f
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 20 kHz to 2 MHz
OSC
DD
R
OSC
. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 5 kW to 250 kW
V
REF
Load Resistance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . >150 kW
SPECIFICATIONS
Limits
Test Conditions
C Suffix 0 to 70_C
Unless Otherwise Specifieda
D Suffix −40 to 85_C
3 V v V v 6.5 V, V = V
S
DD
DD
Parameter
Reference
Symbol
Minb
Typ
Maxb
Unit
GND = P
GND
I
= −10 mA
1.455
1.477
1.545
1.523
REF
Output Voltage
V
REF
V
T
A
= 25_C
1.50
Oscillator
c
Maximum Frequency
f
f
V
= 5 V, C
= 47 pF, R
= 5.0 kW
2.0
MAX
DD
OSC
OSC
MHz
V
= 5 V
DD
Accuracy
0.85
1.0
1.0
1.15
8
OSC
C
OSC
= 100 pF, R
= 7.50 kW, T = 25_C
OSC
A
R
OSC
Voltage
V
ROSC
V
c
Voltage Stability
Temperature Stability
4 V v V v 6 V, Ref to 5 V, T = 25_C
−8
DD
A
Df/f
%
c
Referenced to 25_C
"5
Error Amplifier (COSC = GND, OSC DISABLED)
Input Bias Current
Open Loop Voltage Gain
Offset Voltage
I
V
NI
= V
, V = 1.0 V
−1.0
47
1.0
15
mA
dB
FB
REF
FB
A
VOL
55
0
V
V
= V
REF
−15
mV
MHz
OS
NI
c
Unity Gain Bandwidth
BW
10
Source (V = 1 V, NI = V
)
−2.0
0.8
60
−1.0
FB
REF
Output Current
I
mA
dB
EA
Sink (V = 2 V, NI = V
)
0.4
FB
REF
c
Power Supply Rejection
P
SRR
3 V < V < 6.5 V
DD
UVLOSET Voltage Monitor
V
V
UVLO
UVLO
High to Low
Low to High
0.85
1.0
1.2
175
1.15
UVLOHL
SET
Under Voltage Lockout
Hysteresis
V
UVLOLH
SET
V
HYS
V
V
mV
UVLOLH − UVLOHL
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
2
Si9140
Vishay Siliconix
SPECIFICATIONS
Limits
Test Conditions
C Suffix 0 to 70_C
Unless Otherwise Specifieda
D Suffix −40 to 85_C
3 V v V v 6.5 V, V = V
S
DD
DD
Parameter
Symbol
Minb
Typ
Maxb
Unit
GND = P
GND
UVLOSET Voltage Monitor
UVLO Input Current
I
V
UVLO
= 0 to V
DD
−100
100
nA
UVLO(SET)
Output Drive (DR and DS)
Output High Voltage
Output Low Voltage
Peak Output Current
Peak Output Current
Break-Before-Make
V
V
= V = 5 V, I = −10 mA
OUT
4.7
4.8
0.2
OH
S
DD
V
V
V
= V = 5 V, I = 10 mA
OUT
0.3
OL
SOURCE
S
DD
I
V
V
= V = 5 V, V
= 0 V
= 5 V
−380
300
40
−260
S
S
DD
OUT
OUT
mA
nS
I
= V = 5 V, V
200
SINK
DD
t
V
DD
= 6.5 V
BBM
Logic
ENABLE Turn-On Delay
ENABLE Logic Low
t
ENABLE Delay to Output, EN , V = 5 V
1.5
ms
dEN
LH DD
V
0.2 V
DD
ENL
V
ENABLE Logic High
ENABLE Input Current
V
0.8 V
DD
ENH
I
ENABLE = 0 to V
−1.0
1.0
mA
EN
DD
VGOOD Comparator (Voltage-Good Comparator)
Input Offset Voltage
Input Hysteresis
Input Bias Current
Output Sink I
V
−45
0
10
0
45
1
OS
V
IN
Common Mode Voltage = V
, V = 5 V
mV
REF DD
V
INHYS
BMON
I
V
IN
= V , V = 5 V
REF DD
−1
mA
mA
mV
I
V
OUT
= 5 V, V = 5 V
6
9
SINK
DD
Output Low Voltage
V
I
= 2 mA, V = 5 V
350
500
OL
OUT
DD
Supply
Supply Current—Normal Mode
Supply Current—Standby Mode
f
= 1 MHz, R
= 7.50 kW
1.6
2.3
mA
OSC
OSC
I
DD
ENABLE < 0.4 V
250
330
mA
Notes
a. 100 pF includes C
on C
.
STRAY
OSC
b. The algebraic convention whereby the most negative value is a minimum and the most positive a maximum, is used in this data sheet.
c. Guaranteed by design, not subject to production testing.
TYPICAL CHARACTERISTICS (25_C UNLESS OTHERWISE NOTED)
V
vs. Supply Voltage
V
REF
vs. Temperature
REF
1.515
1.510
1.505
1.500
1.495
1.490
1.485
1.510
1.505
1.500
1.495
1.490
1.485
1.480
V
REF
with 10 mA Load
V
DD
= 3 V
V
DD
= 6 V
3.0
3.5
4.0
V
4.5
5.0
5.5
6.0
6.5
−50
−25
0
25
50
75
100
125
− Supply Voltage (V)
t − Temperature (_C)
DD
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
3
Si9140
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS OTHERWISE NOTED)
V
vs. Load Current
Error Amplifier Gain and Phase
REF
80
60
40
1.515
1.510
1.505
1.500
1.495
1.490
1.485
0
Gain
−30
3.0, 3.6 V
6.5 V
Phase
20
0
−60
−90
5.0 V
−20
−120
−150
−40
0
5
10
15
20
25
30
10
0.0001 0.001
0.01
0.1
1
100
V
REF
− Sourcing Current (mA)
f − Frequency (MHz)
Standby Current
vs. Supply Voltage and Temperature
Supply Current
vs. Supply Voltage and Temperature
1.8
1.6
1.4
1.2
1.0
260
70_C
C
= 10 pF
L
f = 1 MHz
T
A
= 85_C
250
240
70_C
25_C
T
= 85_C
A
0_C
230
220
210
25_C
−40_C
0_C
−40_C
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
V
DD
− Supply Voltage (V)
V
DD
− Supply Voltage (V)
DR Sourcing Current vs. Supply Voltage
DR Sinking Current vs. Supply Voltage
600
500
400
300
200
100
600
500
400
300
200
100
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
V
DD
− Supply Voltage (V)
V
DD
− Supply Voltage (V)
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
4
Si9140
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS OTHERWISE NOTED)
DS Sourcing vs. Supply Voltage
DS Sinking Current vs. Supply Voltage
600
500
400
300
200
100
600
500
400
300
200
100
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
V
DD
− Supply Voltage (V)
V
DD
− Supply Voltage (V)
Switching Frequency vs. Supply Voltage
Frequency vs. R
/C
OSC OSC
10.00
1.00
0.10
0.01
1.2
1.1
1.0
0.9
0.8
R
OSC
C
OSC
= 7.50 kW
= 100 pF
4.99 kW
12.1 kW
24.9 kW
49.9 kW
100 kW
249 kW
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
40
200
300
V
DD
− Supply Voltage (V)
C
OSC
− Capacitance (pF)
Enable Turn-OFF Delay to Output
UVLO Hysteresis vs. Supply Voltage
70
60
50
40
30
20
215
195
175
155
135
115
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
V
DD
− Supply Voltage (V)
V
DD
− Supply Voltage (V)
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
5
Si9140
Vishay Siliconix
TYPICAL CHARACTERISTICS (25_C UNLESS OTHERWISE NOTED)
V
GOOD
Sinking Current vs. Supply Voltage
20
16
12
8
4
0
3.0
3.5
4.0
4.5
5.0
5.5
6.0
6.5
V
DD
− Supply Voltage (V)
PIN CONFIGURATIONS AND ORDERING INFORMATION
SOIC-16
TSSOP-16
1
2
3
V
16
15
14
V
S
DD
V
V
S
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
DD
D
D
MON
R
D
R
D
S
MON
GOOD
V
S
GOOD
V
COMP
FB
PGND
UVLO
COMP
FB
4
5
13
12
PGND
UVLO
SET
SET
NI
C
OSC
R
OSC
NI
6
7
8
C
11
10
9
OSC
OSC
V
REF
GND
ENABLE
V
REF
R
Top View
GND
ENABLE
Top View
ORDERING INFORMATION−SOIC-16
ORDERING INFORMATIONꢀTSSOP-16
Part Number
Temperature Range
Part Number
Temperature Range
Si9140CY
Si9140CQ
Si9140CY-T1
Si9140CQ-T1
Si9140CQ-T1—E3
Si9140DQ
0_ to 70_C
0_ to 70_C
Si9140CY-T1—E3
Si9140DY
Si9140DY-T1
Si9140DQ-T1
Si9140DQ-T1—E3
−40_ to 85_C
−40_ to 85_C
Si9140DY-T1—E3
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
6
Si9140
Vishay Siliconix
PIN DESCRIPTION
Pin 1: VDD
operation is disabled, supply current is reduced, the oscillator
stops and DS goes high while DR goes low.
The positive power supply for all functional blocks except
output driver. A bypass capacitor of 0.1 mF (minimum) is
recommended.
Pin 10: ROSC
A resistor connected from this pin to ground sets the
oscillator’s capacitor COSC, charge and discharge current.
See the oscillator section of the description of operation.
Pin 2: MON
Non-inverting input of a comparator. Inverting input is tied
internally to reference voltage. This comparator is typically
used to monitor the output voltage and to flag the processor
when the output voltage falls out of regulation.
Pin 11: COSC
An external capacitor is connected to this pin to set the
oscillator frequency.
Pin 3: VGOOD
This is an open drain output. It will be held at ground when the
voltage at MON (Pin 2) is less than the internal reference. An
external pull-up resistor will pull this pin high if the MON pin (Pin
2) is higher than the VREF. (Refer to Pin 2 description.)
0.75
ROSC COSC
(at V = 5.0 V)
DD
fOSC
]
Pin 4: COMP
Pin 12: UVLOSET
This pin is the output of the error amplifier. A compensation
network is connected from this pin to the FB pin to stabilize the
system. This pin drives one input of the internal pulse width
modulation comparator.
This pin will place the chip in the standby mode if the UVLOSET
voltage drops below 1.2 V. Once the UVLOSET voltage
exceeds 1.2 V, the chip operates normally. There is a built-in
hysteresis of 165 mV.
Pin 5: FB
Pin 13: PGND
The inverting input of the error amplifier. An external resistor
divider is connected to this pin to set the regulated output
voltage. The compensation network is also connected to this
pin.
The negative return for the VS supply.
Pin 14: DS
Pin 6: NI
This CMOS push-pull output pin drives the external p-channel
The non-inverting input of the error amplifier. In normal
operation it is externally connected to VREF or an external
reference.
MOSFET. This pin will be high in the standby mode.
break-before-make function between DS and DR is built-in.
A
Pin 15: DR
Pin 7: VREF
This pin supplies a 1.5-V reference.
This CMOS push-pull output pin drives the external n-channel
MOSFET. This pin will be low in the standby mode.
A
break-before-make function between the DS and DR is built-in.
Pin 8: GND (Ground)
Pin 9: ENABLE
Pin 16: VS
A logic high on this pin allows normal operation. A logic low
places the chip in the standby mode. In standby mode normal
The positive terminal of the power supply which powers the
CMOS output drivers. A bypass capacitor is required.
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
7
Si9140
Vishay Siliconix
FUNCTIONAL BLOCK DIAGRAM
V
REF
1.5-V Reference
Generator
V
DD
V
REF
UVLO
V
UVLO
UVLO
SET
GND
V
UVLO
ENABLE
COMP
V
P
S
V
S
Error Amp
NI
+
+
FB
Driver
D
−
S
−
GND
Logic
and
P
GND
BBM
V
S
Control
C
R
OSC
Driver
D
R
Oscillator
OSC
P
GND
V
GOOD
MON
+
V
REF
−
TIMING WAVEFORMS
5 V
0 V
ENABLE
1.5 V
V
COMP
V
COSC
1 V
t
BBM
D
S
D
R
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
8
Si9140
Vishay Siliconix
DESCRIPTION OF OPERATION
Schematics of the Si9140 dc-to-dc conversion solutions for
high-performance PC microprocessors are shown in Figure 1
and 2 respectively. These solutions are geared to meet the
extremely demanding transient regulation and power
requirements of these new microprocessors at minimal cost
and with a minimal parts count. The two solutions are nearly
identical, except for slight variations in output voltage, load
transient amplitude, and specified power. Figure 3 is a
schematic diagram for a 3.3-V logic converter.
5 V
(V
)
IN
V
CCP
Coiltronics
L1
R3
CTX07-12877
2 x Si4435DY
2 x Si4410DY
+
100
1.5 mH
C3
0.1 mF
R1
20 k
R2
2.9 V
(V
C1
10 k
)
2 x 220 mF
10 V
OS-CON
OUT
D1
D1FS4
+
Power-Good
C2
3 x 330 mF
6.3V OS-CON
R4
24.9 k
U1
Si9140
C4, 5.6 pF
1
2
3
4
5
6
7
8
16
V
V
DD
S
15
14
13
12
11
10
9
R7
100 k
MON
DR
R13
C8
R5
10 k 1 mF
C5, 180 pF
V
GOOD
D
S
PGND
240 k
COMP
FB
UVLO
SET
R12
13.3 k,
0.1%
C
R
NI
OSC
R6
C9
V
REF
OSC
220 pF
R8
4.99 k
C6
0.1 mF
C7
0.1 mF
ENABLE
GND
40.2 k
R9
11 k
C10, 180 pF
R11, 4.7 k
R10
14.2 k
0.1%
FIGURE 1. 2.9 V @ 10 A
5 V
(V
)
IN
V
CCP
R3
L1
Coiltronics
CTX07-12877
2 x Si4435DY
Si4410DY
+
100
1.5 mH
C3
0.1 mF
R1
20 k
R2
10 k
2.5 V
C1
(V
OUT
)
2 x 220 mF
10 V
OS-CON
D1
D1FS4
+
Power-Good
U1
R4
40.2 k
C2
3 x 330 mF 6.3V
Si9140
OS-CON
C4, 5.6 pF
1
16
15
14
13
12
11
10
9
V
V
DD
S
2
3
4
5
6
7
8
R7
100 k
MON
DR
R13
C8
R5
10 k 1 mF
C5, 180 pF
V
GOOD
D
S
PGND
240 k
COMP
FB
UVLO
R12
13.3 k,
0.1%
SET
C
R
NI
OSC
R6
C9
V
REF
OSC
220 pF
R8
4.99 k
C6
0.1 mF
C7
0.1 mF
ENABLE
GND
40.2 k
R9
11 k
C10, 180 pF
R11, 4.7 k
R10
20 k
0.1%
FIGURE 2. 2.5 V @ 8.5 A
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
9
Si9140
Vishay Siliconix
5 V
(V
IN
)
R3
100
L1
Coiltronics
Si4435DY
Si4410DY
+
10 mH
CTX07-12891
C3
0.1 mF
3.3 V
(V
C1
2 x 220 mF
TPS
)
OUT
D1
D1FS4
+
Tantalum
C2
3 x 330 mF
TPS
Tantalum
U1
Si9140
C4, 330 pF
1
16
15
14
13
12
11
10
9
V
V
DD
S
2
3
4
5
6
7
8
R7
100 k
MON
DR
R13
C8
R5
10 k 1 mF
C5, 1000 pF
V
GOOD
D
S
PGND
16.2 k
COMP
FB
UVLO
SET
C
R
NI
OSC
R6
C9
220 pF
R12, 13.3 k
V
REF
OSC
R8
40.2 k
4.99 k
C6
0.1 mF
C7
0.1 mF
ENABLE
GND
R9
20 k
C10
R11
1000 pF 4.7 k
R10
11 k
FIGURE 3. 3.3 V@ 5 A
5 V
(V
IN
)
R3
100
L1
10 mH
Coiltronics
CTX07-12891
Si4435DY
+
C3
0.1 mF
C1
1.5 V
OUT
2 x 220 mF
(V
)
D1
D1FS4
+
Si4410DY
TPS
Tantalum
C2
3 x 330 mF
TPS
Tantalum
U1
Si9140
C4, 330 pF
1
16
V
DD
V
S
2
3
4
5
6
7
8
15
14
13
12
11
10
9
R7
MON
DR
R13
C8
100 k
R5
10 k 1 mF
C5, 1000 pF
V
GOOD
D
S
PGND
16.2 k
COMP
FB
UVLO
SET
C
R
NI
OSC
R6
R12, 13.3 k
C9
V
REF
OSC
220 pF
R8
40.2 k
4.99 k
C6
0.1 mF
C7
0.1 mF
ENABLE
GND
R9
20 k
C10
1000 pF
R11
4.7 k
+
FIGURE 4. 1.5-V Converter for GTL Bus @ 5 A
Figure 4 is a schematic diagram of a converter which produces
1.5 V for a GTL bus.
D Switch and Synchronous Rectification
MOSFETs—delivers the power to the load
D Inductor—filters and stores the energy
D Input/Output Capacitor—filters the ripple
Each of these dc-to-dc converters has four major sections:
D PWM Controller—regulates the output voltage
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
10
Si9140
Vishay Siliconix
The functions of each circuit are explained in detail below.
Design equations are provided to optimize each application
circuit.
The error amplifier of the PWM controller plays a major role in
determining the output voltage, stability, and the transient
response of the power supply. In the Si9140, the non-inverting
input of the error amplifier is available for use with an external
precision reference for tighter tolerance regulation. With a
two-pair lead-lag compensation network, it is easy to create a
stable 100-kHz closed loop converter with the Si9140 error
amplifier.
PWM Controller
There are generally two types of controllers, voltage mode or
current mode. In voltage mode control, an error voltage is
generated by comparing the output voltage to the reference
voltage. The error voltage is then compared to an artificial
ramp, and the result is the duty cycle necessary to regulate the
output voltage. In current mode, an actual inductor current is
used, in place of the artificial ramp, to sense the voltage across
the current sense resistor.
The Si9140 achieves the 5-mS transient response by
generating a 100-kHz closed-loop bandwidth. This is possible
only by switching above 400 kHz and utilizing an error amplifier
with at least a 10-MHz bandwidth. The Si9140 controller has
a 25-MHz unity gain bandwidth error amplifier. The switching
frequency must be at least four times greater than the desired
closed-loop bandwidth to prevent oscillation. To respond to
the stimuli, the error amplifier bandwidth needs to be at least
10 times larger than the desired bandwidth.
The logic and timing sequence for voltage mode control is
shown in Figure 5. The Si9140 offers voltage mode control,
which is better suited for applications requiring both fast
transient response and high output current.
Current mode control requires a current sense resistor to
monitor the inductor current. A 10-mW sense resistor in a 10-A
design will dissipate 1 W, decreasing efficiency by 3.5%. Such
a design would require a 2-W resistor to satisfy derating criteria,
besides requiring additional board space. Voltage mode control
is a second-order LC system and has a faster natural transient
response compared to current mode control (first-order RC
system). Current mode has the advantage of providing an
inherently good line regulation. But the situations where line
voltage is fixed, as in the point-of-use conversion for
microprocessors, this feature is wasted. Current mode control
also provides automatic pulse-to-pulse current limiting. This
feature requires a current sense resistor as stated above. These
characteristics make voltage mode control ideal for high-end
microprocessor power supplies.
Phase
Gain
Frequency (Hz)
FIGURE 6. 100-kHz BW Synchronous Buck Converter
OSC
COMP
The Si9140 solution requires only three 330-mF OS-CON
capacitors on the output of power supply to meet the 10-A
transient requirement. Other converter solutions on the market
with 20- to 50-kHz closed loop bandwidths typically require two
to five times the output capacitance specified above to match
the Si9140’s performance.
D
S
D
R
The theoretical issues and analytical steps involved in
compensating a feedback network are beyond the scope of
this application note. However, to ease the converter design
for today’s high-performance microprocessors, typical
component values for the feedback network are provided in
Table 1 for various combinations of output capacitance. Figure
6 shows the Bode plot (frequency domain) of the 2.9-V
converter shown schematically in Figure 1.
FIGURE 5. Voltage Mode Logic and Timing Diagram
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
11
Si9140
Vishay Siliconix
reference and 3.5% transient load regulation safely complies
with the "5% regulation requirement. If additional margin is
desired, an external precision reference can be used in place
of the internal 1.5-V reference.
TABLE 1.
FEEDBACK NETWORK COMPONENT VALUES
Total Output and
Decoupling Capacitance
C4
C5
R5
a
3 x 330 mF . . . . . . . . . Os-con
b
Switching and Synchronous Rectification MOSFETs
6 x 100 mF . . . . . . . . . Tantalum
5.6 pF
180 pF
240 k
b
25 x 1 mF . . . . . . . . . . Ceramic
a
2 x 330 mF . . . . . . . . . Os-con
The synchronous gate drive outputs of Si9140 PWM controller
drive the high-side p-channel switch MOSFET and the
low-side n-channel synchronous rectifier MOSFET. The
physical difference between the non-synchronous to
synchronous rectification requires an additional MOSFET
across the free-wheeling diode (D1). The inductor current will
reach 0 A if the peak-to-peak inductor current equals twice the
output current. In synchronous rectification mode, current is
allowed to flow backwards from the inductor (L1) through the
synchronous MOSFET (Q3) and to the output capacitor (C2)
once the current reaches 0 A. Refer to schematic on Figure 1.
In non-synchronous rectification, the diode (D1) prevents the
current from flowing in the reverse direction. This minor
difference has a drastic affect on the performance of a power
supply. By allowing the current to flow in the reverse direction,
it preserves the continuous inductor current mode, maintaining
the wide converter bandwidth and improving efficiency. Also,
maintaining the continuous current mode during light load to
full load guarantees consistent transient response throughout
a wide range of load conditions.
b
4 x 100 mF . . . . . . . . . Tantalum
10 pF
10 pF
220 pF
100 pF
200 k
100 k
b
25 x 1 mF . . . . . . . . . . Ceramic
a
3 x 330 mF . . . . . . . . . Tantalum
b
4 x 100 mF . . . . . . . . . Tantalum
b
25 x 1 mF . . . . . . . . . . Ceramic
a. Power supply output capacitance.
b. mprocessor decoupling capacitance.
Figure 7 is the measured transient response (time domain) for
the 10-A step response. The measured transient response
shows the processor voltage regulating to 70 mV, well within
the 0.145-V regulation.
The Si9140’s switching frequency is determined by the
external ROSC and COSC values, allowing designers to set the
switching frequency of their choice. For applications where
space is the main constraint, the switching frequency can be
set as high as 2 MHz to minimize inductor and output capacitor
size. In applications where efficiency is the main concern, the
switching frequency can be set low to maximize battery life.
The switching frequency for high-performance processors
applications circuits are set for 400 kHz. The equation for
switching frequency is:
The transition from stop clock and auto halt to active mode is
a perfect example. The microprocessor current can vary from
0.5 A to 10 A or greater during these transitions. If the
converter were to operate in discontinuous current mode
during the stop clock and auto halt modes, the transfer function
of the converter would be different compared to operation in
the active mode. In discontinuous current mode, the converter
bandwidth can be 10 to 15 times lower than the continuous
current mode (Figure 8). Therefore, the response time will also
be 10 to 15 times slower, violating the microprocessor’s
regulator requirements. This could result in unreliable
operation of the microprocessor.
0.75
ROSC COSC
(at V = 5.0 V)
DD
fOSC
[
The precision reference is set at 1.5 V"1.5%. The reference
is capable of sourcing up to 1 mA. The combination of 1.5%
mP
Voltage
2.9 V
mP
Current
10 A
5 A
0 A
a) Transient Response from 0- to 10-A Step Load
b) Transient Response from 10- to 0-A Step Load
FIGURE 7.
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
12
Si9140
Vishay Siliconix
For these reasons, synchronous rectification is a must in
today’s microprocessors power supply design. Pulse-
Worst case current of 10 A can be handled with two paralleled
Si4435DY and two paralleled Si4410DY MOSFETs, which
results in the efficiency levels shown in Figure 9.
skipping modes are undesirable in high-performance
microprocessor power supplies, especially when the minimum
load current is as high as 500 mA. This pulse-skipping mode
disables the synchronous rectification during light load and
generates a random noise spectrum which may produce EMI
problems.
100
V
OUT
= 5 V
IN
V
= 2.9 V
Siliconix’ TrenchFETt technology has resulted in 20-mW
n-channel (Si4410DY) and 35-mW p-channel (Si4435DY)
MOSFETs in the SO-8 surface-mount package. These LITTLE
FOOTr products totally eliminate the need for an external
heatsink.
95
90
85
80
Phase
0
2
4
6
8
10
I
(A)
OUT
FIGURE 9. Efficiency
Gain
Good electrical designs must provide an adequate margin for
the specification, but they should not be grossly overdesigned
to lower costs. LITTLE FOOT power MOSFETs allow
designers to balance cost and performance considerations
without sacrificing either. If the design requires only an 8.5-A
continuous current, for example, one Si4410DY can be
eliminated. Table 2 shows the number of MOSFETs required
to handle the various output current levels of today’s high-
performance microprocessors. For other output power levels,
the equations below should be used to calculate the power
handling capability of the MOSFET.
Frequency (Hz)
FIGURE 8. Non-Synchronous Converter BW
TABLE 2.
CONVERTER REQUIREMENTS (FIGURES 1, 2, AND 3)
IO (A)
Maxi-
mum
Quantity High-Side P-Channel
Quantity Low-Side N-Channel
Si4410DY
Quantity Input (C1-C3)
Capacitor Os-con 220 mF
Si4435DY
5 A
8.5 A
10 A
1
2
2
3
1
1
2
2
1
2
2
3
14.5 A
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
13
Si9140
Vishay Siliconix
QSW VIN fOSC IPP VO tC fOSC
2
PDissipation in switch + IRMS SW RSW
)
)
2
2
VO
3 VIN
IPEAK2 ) IPP2 ) IPEAK IPP
ǒ
+ Ǹ
Ǔ
IRMS SW
QRECT VIN fOSC
2
PDissipation in synchronous rectification + IRMS RECT RRECT
)
2
(V – V
IN
)
O
2
2
) I
ǒI
Ǹ
Ǔ
I
PP
I
+
) I
PEAK
PP
PEAK
RMS RECT
3 V
IN
I
R
=
=
=
=
=
=
=
=
=
=
=
=
Switch rms current
RMSSW
I
= I
+ DI
PP
PEAK
Switch on resistance
Synchronous rectifier rms current
Synchronous rectifier on resistance
Total gate charge of switch
Total gate charge of synchronous rectifier
Input voltage
Output voltage
Output current
Switching frequency
efficiency
Crossover time
SW
I
RMSRECT
R
Q
Q
V
V
RECT
2
VO
SW
RECT
IN
DI +
L fOSC VIN
O
I
f
O
P
IN – (0.5 VO DI)
IPEAK
+
OSC
VO
h
t
C
VO IO
PIN
+
h
Current
I
O
I
PP
I
PEAK
0 A
time
Inductor
negligible compared to the wire loss. Kool Mu is the best
material to use at 500 kHz to deliver 30 W in the minimum
volume. Ferrite has a lower core cost and loss at this
frequency, but the core size is fairly large. If the power supply
is designed on the motherboard and space is not a critical
issue, ferrite is a better choice.
The size and value of the inductor are critical in meeting overall
circuit dimensional requirements and in assuring proper
transient voltage regulation. The size of the core is determined
by the output power, the material of the core, and the operating
frequency. To handle higher output power, the core must be
larger. Luckily, a higher switching frequency will lower the
inductance value, decreasing the core size. However, a higher
switching frequency can also mean greater core loss.
The higher switching frequency reduces the core size by
decreasing the amount of energy that must be stored between
switching periods. It also accelerates the transient response to
the load by decreasing the inductance value. The inductance
is calculated with following equation:
In applications where the dc flux density is high and the ac flux
density swing is only 100 to 200 gauss, the core loss will be
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
14
Si9140
Vishay Siliconix
2
of Sanyo (OS-CON) input capacitors required to handle
various output currents are specified in Table 2.
VO
VIN DI fOSC
L +
Output Capacitor
DI = desired output current ripple. Typically DI = 25% of maximum
output current.
To regulate the microprocessor’s input voltage within 145 mV
during 10-A load transients, a large output capacitance with
low ESR is required. The output capacitor of the power supply
and decoupling capacitors at the microprocessor must hold up
the processor voltage until the power supply responds to the
change. Even with fastest known switching solution, it still
takes three 330-mF OS-CON capacitors to handle the load
transient. If it weren’t for the 10-A load transient, the output
capacitor would not need a low ESR value. The fundamental
output ripple current in a continuous step-down converter is
much lower than the input ripple current. Maintaining voltage
regulation during transients requires an ESR in the range of
Finally, the time required to ramp up the current in the inductor
can be reduced with smaller inductance. A quick response
from the power supply relaxes the decoupling capacitance
required at the microprocessor, reducing the overall solution
cost and size.
Input Capacitor
The input capacitor’s function is to filter the raw power and
serve as the local power source to eliminate power-up and
transient surge failures. The type and characteristics of input
capacitors are determined by the input power and inductance
of the step-down converter. The ripple current handling
requirement usually dominates the selection criteria. The
capacitance required to maintain regulation will automatically
be achieved once it meets the ripple current requirement. The
following equation calculates the ripple current of the input
capacitor:
30 mW.
For microprocessors with lower transient
requirements, the number of output and decoupling capacitors
can be reduced. The lower transient requirements also allows
greater consideration for Tantalum or Nichicon PL series
capacitors.
Conclusion
The Si9140 synchronous Buck controller’s ability to switch up
to 1 MHz combined with a 25-MHz error amplifier provides the
best solution in powering high- performance microprocessors.
The high switching frequency reduces inductor size without
compromising output ripple voltage. The wide converter
bandwidth generated with the help of a 25-MHz error amplifier
reduces the amount of decoupling capacitors required to
handle the extreme transient requirement. The Si9140’s
synchronous fixed-frequency operation eliminates the pulse
skipping mode that generates random unpredictable
EMI/EMC problems in desktop and notebook computers. The
synchronous rectification also allows the converter to operate
in continuous current mode, independent of output load
current. This preserves the wide closed-loop converter
bandwidth required to meet the transient demand of the
microprocessor as it transitions from stop clock and auto halt
to active mode. The synchronous rectification improves the
efficiency of the converter by substituting the much smaller I2R
MOSFET loss for the VI diode loss. The need for heatsinking
is eliminated by using low rDS(on) TrenchFETs (Si4410DY and
Si4435DY).
IRIPPLE
IRMSSW2 – IIN
2
+ Ǹ
An aluminum-electrolytic capacitor from Sanyo (OS-CON),
AVX (TPS Tantalum), or Nichicon (PL series) should be used
in high-power (30-W) applications to handle the ripple current.
The Sanyo capacitor is smaller and handles higher ripple
current than Nichicon, but at higher cost than the Nichicon
product. The AVX Tantalum capacitor has the best
capacitance and current handling capability per volume ratio,
but it takes extra surface area compared to OS-CON or PL
series. The TPS capacitors, lead time and cost have
increased drastically in the recent past due to high demand,
causing designers to shy away from the TPS Tantalum
capacitors. Nichicon capacitors can be used to provide an
economical solution if space is available or a large bulk
capacitance is already present on the input line. The number
Document Number: 70026
S-40699—Rev. H, 19-Apr-04
www.vishay.com
15
Legal Disclaimer Notice
Vishay
Notice
Specifications of the products displayed herein are subject to change without notice. Vishay Intertechnology, Inc.,
or anyone on its behalf, assumes no responsibility or liability for any errors or inaccuracies.
Information contained herein is intended to provide a product description only. No license, express or implied, by
estoppel or otherwise, to any intellectual property rights is granted by this document. Except as provided in Vishay's
terms and conditions of sale for such products, Vishay assumes no liability whatsoever, and disclaims any express
or implied warranty, relating to sale and/or use of Vishay products including liability or warranties relating to fitness
for a particular purpose, merchantability, or infringement of any patent, copyright, or other intellectual property right.
The products shown herein are not designed for use in medical, life-saving, or life-sustaining applications.
Customers using or selling these products for use in such applications do so at their own risk and agree to fully
indemnify Vishay for any damages resulting from such improper use or sale.
Document Number: 91000
Revision: 08-Apr-05
www.vishay.com
1
Package Information
Vishay Siliconix
SOIC (NARROW): 16-LEAD (POWER IC ONLY)
JEDEC Part Number: MS-012
MILLIMETERS
INCHES
Dim
A
A1
B
C
D
Min
1.35
0.10
0.38
0.18
9.80
3.80
Max
1.75
0.20
0.51
0.23
10.00
4.00
Min
Max
0.069
0.008
0.020
0.009
0.393
0.157
0.053
0.004
0.015
0.007
0.385
0.149
E
16 15
14 13
12 11
10
7
9
8
1.27 BSC
0.050 BSC
e
H
L
Ĭ
5.80
0.50
0_
6.20
0.93
8_
0.228
0.020
0_
0.244
0.037
8_
E
1
2
3
4
5
6
ECN: S-40080—Rev. A, 02-Feb-04
DWG: 5912
H
D
C
All Leads
0.101 mm
0.004 IN
A1
Ĭ
L
e
B
Document Number: 72807
28-Jan-04
www.vishay.com
1
Package Information
Vishay Siliconix
TSSOP: 16-LEAD
DIMENSIONS IN MILLIMETERS
Symbols
Min
-
Nom
1.10
0.10
1.00
0.28
0.127
5.00
6.40
4.40
0.65
0.60
1.00
-
Max
1.20
0.15
1.05
0.38
-
A
A1
A2
B
0.05
-
0.22
-
C
D
4.90
6.10
4.30
-
5.10
6.70
4.50
-
E
E1
e
L
0.50
0.90
-
0.70
1.10
0.10
6°
L1
y
θ1
0°
3°
ECN: S-61920-Rev. D, 23-Oct-06
DWG: 5624
Document Number: 74417
23-Oct-06
www.vishay.com
1
Legal Disclaimer Notice
Vishay
Disclaimer
ALL PRODUCT, PRODUCT SPECIFICATIONS AND DATA ARE SUBJECT TO CHANGE WITHOUT NOTICE TO IMPROVE
RELIABILITY, FUNCTION OR DESIGN OR OTHERWISE.
Vishay Intertechnology, Inc., its affiliates, agents, and employees, and all persons acting on its or their behalf (collectively,
“Vishay”), disclaim any and all liability for any errors, inaccuracies or incompleteness contained in any datasheet or in any other
disclosure relating to any product.
Vishay makes no warranty, representation or guarantee regarding the suitability of the products for any particular purpose or
the continuing production of any product. To the maximum extent permitted by applicable law, Vishay disclaims (i) any and all
liability arising out of the application or use of any product, (ii) any and all liability, including without limitation special,
consequential or incidental damages, and (iii) any and all implied warranties, including warranties of fitness for particular
purpose, non-infringement and merchantability.
Statements regarding the suitability of products for certain types of applications are based on Vishay’s knowledge of typical
requirements that are often placed on Vishay products in generic applications. Such statements are not binding statements
about the suitability of products for a particular application. It is the customer’s responsibility to validate that a particular
product with the properties described in the product specification is suitable for use in a particular application. Parameters
provided in datasheets and/or specifications may vary in different applications and performance may vary over time. All
operating parameters, including typical parameters, must be validated for each customer application by the customer’s
technical experts. Product specifications do not expand or otherwise modify Vishay’s terms and conditions of purchase,
including but not limited to the warranty expressed therein.
Except as expressly indicated in writing, Vishay products are not designed for use in medical, life-saving, or life-sustaining
applications or for any other application in which the failure of the Vishay product could result in personal injury or death.
Customers using or selling Vishay products not expressly indicated for use in such applications do so at their own risk and agree
to fully indemnify and hold Vishay and its distributors harmless from and against any and all claims, liabilities, expenses and
damages arising or resulting in connection with such use or sale, including attorneys fees, even if such claim alleges that Vishay
or its distributor was negligent regarding the design or manufacture of the part. Please contact authorized Vishay personnel to
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No license, express or implied, by estoppel or otherwise, to any intellectual property rights is granted by this document or by
any conduct of Vishay. Product names and markings noted herein may be trademarks of their respective owners.
Document Number: 91000
Revision: 11-Mar-11
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1
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