VISHAY SI9130

Not recommended for new designs, please refer to Si786
Si9130
Vishay Siliconix
Pin-Programmable Dual Controller - Portable PCs
FEATURES
• Fixed 5 V and Programmable 3.3 V, 3.45 V, or
3.6 V Step-Down Converters
• Less than 500 µA Quiescent Current per Converter
• 25 µA Shutdown Current
• 5.5 V to 30 V Operating Range
DESCRIPTION
The Si9130 Pin-programmable Dual Controller for Portable
PCs is a pin-programmable version of the Si786 dual-output
power supply controller for notebook computers. The Buck
controllers provide 5 V and a pin-programmable output
delivering 3.3 V, 3.45 V, or 3.6 V.
The circuit is a system level integration of two step-down
controllers and micropower 5 V and 3.3 V linear regulators.
The controllers perform high efficiency conversion of the
battery pack energy (typically 12 V) or the output of an ac to
dc wall converter (typically 18 V to 24 V dc) to 5 V and 3.3 V
system supply voltages. The micropower linear regulator can
be used to keep power management and back-up circuitry
alive during the shutdown of the step-down converters.
A complete power conversion and management system can
be implemented with the Si9130 Pin-programmable Dual
Controller for Portable PCs, an inexpensive linear regulator,
the Si9140 SMP Controller for High Performance Processor
Power Supplies, five Si4410 N-Channel TrenchFET® Power
MOSFETs, one Si4435 P-Channel TrenchFET Power
MOSFET, and two Si9712 PC Card (PCMCIA) Interface
Switches.
The Si9130 is available in both standard and lead (Pb)-free
28-pin SSOP packages and specified to operate over the
commercial (0 °C to 70 °C) and extended commercial
(- 10 °C to 90 °C) temperature ranges. See Ordering
Information for corresponding part numbers.
FUNCTIONAL BLOCK DIAGRAM
5.5 V to 30 V
SHUTDOWN
3.3 V
Si9130
Power
Section
5V
µP
Memory
Peripherals
5 V ON/OFF
3.3 V ON/OFF
SYNC
Document Number: 70190
S11-0975-Rev. G, 16-May-11
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Si9130
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ABSOLUTE MAXIMUM RATINGS
Parameter
Limit
V+ to GND
- 0.3 to 36
PGND to GND
Unit
±2
VL to GND
- 0.3 to 7
BST3, BST5 to GND
- 0.3 to 36
LX3 to BST3
- 7 to 0.3
LX5 to BST5
- 7 to 0.3
Inputs/Outputs to GND (3.45 ADJ, 3.6 ADJ, SHDN, ON5, REF, SS5, CS5, FB5,
SYNC, CS3, FB3, SS3, ON3)
V
- 0.3, (VL + 0.3)
DL3, DL5 to PGND
- 0.3, (VL + 0.3)
DH3 to LX3
- 0.3 (BST3 + 0.3)
DH5 to LX5
- 0.3 (BST5 + 0.3)
REF, VL Short to GND
Momentary
REF Current
20
VL Current
50
Continuous Power Dissipation (TA = 70 °C)a
Operating Temperature Range:
28-Pin SSOPb
mA
762
mW
Si9130CG
0 to 70
Si9130LG
- 10 to 90
Lead Temperature (soldering, 10 sec)
°C
300
Notes:
a. Device Mounted with all leads soldered or welded to PC board.
b. Derate 9.52 mW/°C above 70 °C.
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.
SPECIFICATIONS
Specific Test Conditions
V+ = 15 V, IVL = IREF = 0 mA, SHDN = ON3 = ON5 = 5 V
Other Digital Input Levels 0 V or 5 V, TA = TMIN to TMAX
Parameter
Limits
Min.a
Typ.b
Max.a
Unit
3.3 V and 5 V Step-Down Controllers
Input Supply Range
5.5
0 mV < (CS5 - FB5) < 70 mV, 6 V < V + < 30 V
(includes load and line regulation)
FB5 Output Voltage
FB3 Output Voltage
0 mV < (CS3 - FB3) < 70 mV
6 V < V + < 30 V
(includes load and line regulation)
30
4.80
5.08
5.20
3.6 ADJ = 3.45 ADJ = OPEN
3.17
3.35
3.46
3.6 ADJ = OPEN
3.45 ADJ = GND
3.32
3.50
3.60
3.6 ADJ = GND
3.45 ADJ = OPEN
3.46
3.65
3.75
V
Load Regulation
Either Controller (CS_ to FB_ = 0 to 70 mV)
2.5
%
Line Regulation
Either Controller (V+ = 6 to 30)
0.03
%/V
Current-Limit Voltage
CS3 - FB3 or CS5 - FB5
SS3/SS5 Source Current
SS3/SS5 Fault Sink Current
80
100
120
mV
2.5
4.0
6.5
µA
2
mA
Internal Regulator and Reference
VL Output Voltage
ON5 = ON3 = 0, 5.5 < V+ < 30
0 mA < IL < 25 mA
4.5
5.5
VL Fault Lockout Voltage
Falling Edge, Hysteresis = 1 %
3.6
4.2
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Document Number: 70190
S11-0975-Rev. G, 16-May-11
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Si9130
Vishay Siliconix
SPECIFICATIONS
Parameter
Specific Test Conditions
V+ = 15 V, IVL = IREF = 0 mA, SHDN = ON3 = ON5 = 5 V
Other Digital Input Levels 0 V or 5 V, TA = TMIN to TMAX
Limits
Min.a
Typ.b
Max.a
Unit
Internal Regulator and Reference
VL/FB5 Switchover Voltage
REF Output Voltage
REF Fault Lockout Voltage
Rising Edge of FB5, Hysteresis = 1 %
4.2
4.7
No External Load
3.24
3.36
Falling Edge
2.4
c
V
3.2
REF Load Regulation
0 mA < IL < 5 mAd
30
V+ Shutdown Current
SHDN = ON3 = ON5 = 0 V, V+ = 30 V
25
40
ON3 = ON5 = 0 V, V+ = 30 V
70
110
FB5 = CS5 = 5.25 V
FB3 = CS3 = 3.5 V
5.5
8.6
mV
FB5 = CS5 = 5.25 V, VL Switched Over to FB5
30
60
µA
V+ Standby Current
Quiescent Power Consumption
(both PWM controllers on)
V+ Off Current
75
mV
µA
Oscillator and Inputs/Outputs
Oscillator Frequency
SYNC = 3.3 V
270
300
330
SYNC = 0 V, 5 V
170
200
230
SYNC High Pulse Width
200
SYNC Low Pulse Width
SYNC Rise/Fall Time
200
Input Low Voltage
Input High Voltage
Input Current
ns
Not Tested
Oscillator SYNC Range
Maximum Duty Cycle
kHz
200
240
350
SYNC = 3.3 V
89
92
SYNC = 0 V, 5 V
92
95
SHDN, ON3, ON5 SYNC
kHz
%
0.8
SHDN, ON3, ON5
2.4
SYNC
VL - 0.5
V
SHDN, ON3, ON5, VIN = 0 V, 5 V
±1
DL3/DL5 Sink/Source Current
VOUT = 2 V
1
DH3/DH5 Sink/Source Current
BST3 - LX3 = BST5 - LX5 = 4.5 V, VOUT = 2 V
1
µA
A
DL3/DL5 On-Resistance
High or Low
7
DH3/DH5 On-Resistance
High or Low
BST3 - LX3 = BST5 - LX5 = 4.5 V
7

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.
c. The main switching outputs track the reference voltage. Loading the reference reduces the main outputs slightly according to the closed-loop
gain (AVCL) and the reference voltage load-regulation error. AVCL for the 3.3 V supply is unity gain. AVCL for the 5 V supply is 1.54.
d. Since the reference uses VL as its supply, its V+ line regulation error is insignificant.
Document Number: 70190
S11-0975-Rev. G, 16-May-11
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Si9130
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TYPICAL CHARACTERISTICS (25 °C unless noted)
100
100
VIN = 6 V
VIN = 6 V
90
VIN = 15 V
80
Efficiency (%)
Efficiency (%)
90
VIN = 30 V
70
VIN = 15 V
80
VIN = 30 V
70
3.3 V Off
SYNC = 0 V, 3.3 V Off
60
60
50
50
0.001
0.01
0.1
1
0.001
10
0.01
0.1
1
10
5 V Output Current (A)
5 V Output Current (A)
Efficiency vs. 5 V Output Current, 300 kHz
Efficiency vs. 5 V Output Current, 200 kHz
100
100
90
90
VIN = 6 V
80
Efficiency (%)
Efficiency (%)
VIN = 6 V
VIN = 15 V
VIN = 30 V
70
80
VIN = 15 V
VIN = 30 V
70
5 V On
SYNC = 0 V, 5 V On
60
60
50
50
0.001
0.01
0.1
1
0.001
10
0.1
1
10
3.3 V Output Current (A)
Efficiency vs. 3.3 V Output Current, 200 kHz
Efficiency vs. 3.3 V Output Current, 300 kHz
0.5
30
25
Standby Supply Current (mA)
Quiescent Supply Current (mA)
0.01
3.3 V Output Current (A)
20
ON3 = ON5 = High
15
10
5
0.4
0.3
ON3 = ON5 = 0 V
0.2
0.1
0.0
0
0
6
12
18
24
Supply Voltage (V)
Quiescent Supply Current vs. Supply Voltage
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4
30
0
6
12
18
24
30
Supply Voltage (V)
Standby Supply Current vs. Supply Voltage
Document Number: 70190
S11-0975-Rev. G, 16-May-11
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THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
Si9130
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TYPICAL CHARACTERISTICS (25 °C unless noted)
1.0
Mimimum V IN to VOUT Differential (V)
Shutdown Supply Current (µA)
100
SHDN = 0 V
75
50
25
5 V Output
Still Regulating
0.8
0.6
300 kHz
0.4
200 kHz
0.2
0.0
0
0
6
12
18
24
30
0.001
0.01
0.1
1
10
5 V Output Current (A)
Supply Voltage (V)
Shutdown Supply Current vs. Supply Voltage
Minimum VIN to VOUT Differential
vs. 5 V Output Current
1000.0
Switching Frequency (kHz)
SYNC = REF (300 kHz)
ON3 = ON5 = 5 V
100.0
10.0
5 V, VIN = 30 V
5 V, VIN = 7.5 V
1.0
3.3 V, VIN = 7.5 V
0.1
0.1
1
10
100
1000
Load Current (mA)
Switching Frequency vs. Load Current
5 V Output
50 mV/div
LX 10 V/div
2 V/div
5 V Output
50 mV/div
200 µS/div
ILoad = 100 mA
VIN = 10 V
Pulse-Skipping Waveforms
Document Number: 70190
S11-0975-Rev. G, 16-May-11
500 ns/div
5 V Output Current = 1 A
VIN = 16 V
Pulse-Width Modulation Mode Waveforms
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TYPICAL CHARACTERISTICS (25 °C unless noted)
3A
3A
LOAD CURRENT
LOAD CURRENT
0A
0A
5 V Output
50 mV/div
200 µS/div
VIN = 15 V
200 µS/div
VIN = 15 V
5 V Load-Transient Response
3.3 V Load-Transient Response
5 V Output
50 mV/div
5 V Output
50 mV/div
VIN, 10 to 16 V
2 V/div
VIN, 16 to 10 V
2 V/div
20 µS/div
ILOAD = 2 A
20 µS/div
ILOAD = 2 A
5 V Line-Transient Response, Rising
20 µS/div
ILOAD = 2 A
3.3 V Line-Transient Response, Rising
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3.3 V Output
50 mV/div
5 V Line-Transient Response, Falling
3.3 V Output
50 mV/div
3.3 V Output
50 mV/div
VIN, 10 to 16 V
2 V/div
VIN, 16 to 10 V
2 V/div
20 µS/div
ILOAD = 2 A
3.3 V Line-Transient Response, Falling
Document Number: 70190
S11-0975-Rev. G, 16-May-11
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Si9130
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PIN CONFIGURATION AND DESCRIPTION
CS3
1
28
FB3
ORDERING INFORMATION
SS3
2
27
DH3
ON3
3
26
LX3
Standard
Part Number
NC
4
25
BST3
Si9130CG
NC
5
24
DL3
Si9130CG-T1 Si9130CG-T1-E3
Si9130LG
NC
6
23
V+
3.6ADJ
7
22
VL
3.45ADJ
8
21
FB5
GND
9
20
PGND
REF
10
19
DL5
SYNC
11
18
BST5
SHDN
12
17
LX5
ON5
13
16
DH5
SS5
14
15
CS5
SSOP-28
Si9130LG-T1
Lead (Pb)-free
Part Number
Si9130LG-T1-E3
Temperature
Range
0 to 70 °C
- 10 to 90 °C
VOUT
5 V and 3.3 V
3.45 V or 3.6 V
Demo Board
Temperature Range
Board Type
Si9130DB
0 to 70 °C
Surface Mount
Top View
PIN DESCRIPTION
Pin
Symbol
Description
1
2
3
4
5
6
7
8
9
10
CS3
SS3
ON3
NC
NC
NC
3.6 ADJ
3.45 ADJ
GND
REF
11
SYNC
Current-sense input for 3.3 V Buck controller - this pins over current threshold is 100 mV with respect to FB3.
Soft-start input for 3.3 V. Connect capacitor from SS3 to GND.
ON/OFF logic input disables the 3.3 V Buck controller. Connect directly to VL for automatic turn-on.
Not internally connected.
Not internally connected.
Not internally connected.
Control input to select 3.6 V output. See Voltage Selection Table for input and output combinations.
Control input to select 3.45 V output. See Voltage Selection Table for input and output combinations.
Analog ground.
3.3 V reference output. Supplies external loads up to 5 mA.
Oscillator control/synchronization input. Connect capacitor to GND, 1 µF/mA output or 0.22 µF minimum. For external
clock synchronization, a rising edge starts a new cycle to start. To use internal 200 kHz oscillator, connect to VL or GND.
For 300 kHz oscillator, connect to REF.
12
SHDN
Shutdown logic input, active low. Connect to VL for automatic turn-on. The 5 V VL supply will not be disabled in shutdown
allowing connection to SHDN.
13
14
15
16
17
18
19
20
21
22
23
24
ON5
SS5
CS5
DH5
LX5
BST5
DL5
PGND
FB5
VL
V+
DL3
ON/OFF logic input disables the 5 V Buck Controller. Connect to VL for automatic turn-on.
Soft-start control input for 5 V Buck controller. Connect capacitor from SS5 to GND.
Current-sense input for 5 V Buck controller - this pins over current threshold is 100 mV referenced to FB3.
Gate-drive output for the 5 V supply high-side N-Channel MOSFET.
Inductor connection for the 5 V supply.
Boost capacitor connection for the 5 V supply.
Gate-drive output for the 5 V supply rectifying N-Channel MOSFET.
Power Ground.
Feedback input for the 5 V Buck controller.
5 V logic supply voltage for internal circuitry - able to source 5 mA external loads. VL remains on with valid voltage at V+.
Supply voltage input.
Gate-drive output for the 3.3 V supply rectifying N-Channel MOSFET.
25
26
27
28
BST3
LX3
DH3
FB3
Boost capacitor connection for the 3.3 V supply.
Inductor connection for the 3.3 V supply.
Gate-drive output for the 3.3 V supply high-side N-Channel MOSFET.
Feedback input for the 3.3 V Buck controller.
Document Number: 70190
S11-0975-Rev. G, 16-May-11
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Si9130
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VOLTAGE SELECTION TABLE
Input
Output
3.45 ADJ
FB3
3.6 ADJ
OPEN
OPEN
3.3 V
GND
OPEN
3.45 V
OPEN
GND
3.6 V
DESCRIPTION OF OPERATION
3.3 V PWM Voltage Selection
(Pins 3.45 ADJ, 3.6 ADJ)
The Si9130 is a dual step-down converter, which takes a
5.5 V to 30 V input and supplies power via two PWM
controllers (see Figure 1). These 5 V and 3.3 V supplies run
on an optional 300 kHz or 200 kHz internal oscillator, or an
external sync signal. Amount of output current is limited by
external components, but can deliver greater than 6 A on
either supply. As well as these two main Buck controllers,
additional loads can be driven from two micropower linear
regulators, one 5 V (VL) and the other 3.3 V (REF) - see
Figure 2. These supplies are each rated to deliver 5 mA. If
the linear regulator circuits fall out of regulation, both Buck
controllers are shut down.
The voltage at this output can be selected to 3.3 V, 3.45 V or
3.6 V, depending on the configuration of pins 3.45 ADJ and
3.6 ADJ. Leaving both pins open results in 3.3V nominal
output. Grounding pin 3.45 ADJ while leaving 3.6 ADJ open
delivers 3.45 V nominal output. Grounding 3.6 ADJ while
leaving 3.45 ADJ open sets a 3.6 V nominal output.
INPUT
5.5 V to 30 V
C1
22 µF
C10
22 µF
100
D2A
1N4148
D2B
1N4148
0.1 µF
+ 5 V at 5 mA
Si9130
C5
0.1 µF
N1
R1
25 mΩ
L1
10 H
23
25
27
26
V+
BST3
VL
BST5
DH3
DH5
LX3
LX5
DL3
DL5
CS3
CS5
FB3
FB5
22
4.7 µF
C4
0.1 µF
18
16
N2
L2
10 µH
17
R2
25 mΩ
+ 3.3 V at 3 A
D1
D1FS4
C7
150 µF
N3
24
1
C12
150 µF
(Note 1)
C9
0.01 F
+ 3.3 V ON/OFF
+ 5 V ON/OFF
SHUTDOWN
OSC SYNC
28
2
3
13
12
11
9
10
SS3
ON3
SS5
3.45ADJ
19
D1
D1FS4
N3
+ 5 V at 3 A
C6
330 µF
15
21
14
8
(Note 1)
C8
0.01 µF
3.45 V Voltage Adjust
ON5
SHDN
3.6ADJ
7
3.6 V Voltage Adjust
SYNC
GND
REF
PGND
20
+ 3.3 V at 5 mA
Note 1: Use short, Kelvin-connected PC board
traces placed very close to one another.
C3
1 µF
Figure 1. Si9130 Application Circuit
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Document Number: 70190
S11-0975-Rev. G, 16-May-11
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Si9130
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currents at power-on are avoided, and power-supplies can
be sequenced with different turn-on delay times by selecting
the correct capacitor value.
3.3 V Switching Supply
The 3.3 V supply is regulated by a current-mode PWM
controller in conjunction with several externals: two
N-Channel MOSFETs, a rectifier, an inductor and output
capacitors (see Figure 1). The gate drive supplied by DH3
needs to be greater than VL , so it is provided by the
bootstrap circuit consisting of a 100 nF capacitor and diode
connected to BST3.
A low-side switching MOSFET connected to DL3 increases
efficiency by reducing the voltage across the rectifier diode.
A low value sense resistor in series with the inductor sets the
maximum current limit, to disallow current overloads at
power-on or in short-circuit situations.
The soft-start feature on the Si9130 is capacitor
programmable; pin SS3 functions as a constant current
source to the external capacitor connected to GND. Excess
V+
VL
3.45ADJ
3.6ADJ
REF
5 V Switching Supply
The 5 V supply is regulated by a current-mode PWM
controller which is nearly the same as the 3.3 V output. The
dropout voltage across the 5 V supply, as shown in the
schematic in Figure 1, is 400 mV (typ) at 2 A. If the voltage
at V+ falls, nearing 5 V, the 5 V supply will lower as well, until
the VL linear regulator output falls below the 4 V
undervoltage lockout threshold. Below this threshold, the 5 V
controller is shut off.
The frequency of both PWM controllers is set at 300 kHz
when the SYNC pin is tied to REF. Connecting SYNC to
either GND or VL sets the frequency at 200 kHz.
FB3
+ 5 V LDO
Linear
Regulator
CS3
3.3 V
PWM
Controller
(See Figure 3)
+ 3.3 V
Reference
ON
BST3
DH3
LX3
DL3
4.5 V
SHDN
ON
SS3
PGND
4V
ON3
FB5
CS5
2.8 V
SYNC
300 kHz/200 kHz
ON
Oscillator
STANDBY
5V
PWM
Controller
(See Figure 3)
BST5
DH5
LX5
DL5
ON
SS5
ON5
Figure 2. Si9130 Block Diagram
Document Number: 70190
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Si9130
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CS_
1X
REF,
3.3 V
(or Internal
5 V Reference)
60 kHz
LPF
FB_
Summing
Comparator
BST_
R
Level
Shift
Q
S
DH_
LX_
OSC
Slope
Comp
25 mV
Minimum Current
(Pulse-Skipping Mode)
VL
Current
Limit
4 µA
0 mV to
100 mV
SS_
ShootThrough
Control
30R
ON_
3.3 V
1R
Synchronous
Rectifier Control
R
S
VL
Level
Shift
Q
DL_
PGND
Figure 3. Si9130 Controller Block Diagram
3.3 V and 5 V Switching Controllers
Each PWM controller on the Si9130 is identical with the
exception of the preset output voltages. The controllers only
share three functional blocks (see Figure 3): the oscillator,
the voltage reference (REF) and the 5 V logic supply (VL).
The 3.3 V and 5 V controllers are independently enabled with
pins ON3 and ON5, respectively. The PWMs are a directsumming type, without the typical integrating error amplifier
along with the phase shift which is a side effect of this type of
topology. Feedback compensation is not needed, as long as
the output capacitance and its ESR requirements are met,
according to the Design Considerations section of this data
sheet.
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The main PWM comparator is an open loop device which is
comprised of three comparators summing four signals: the
feedback voltage error signal, current sense signal, slopecompensation ramp and voltage reference as shown in
Figure 3. This method of control comes closer to the ideal of
maintaining the output voltage on a cycle-by-cycle basis.
When the load demands high current levels, the controller is
in full PWM mode. Every cycle from the oscillator asserts the
output latch and drives the gate of the high-side MOSFET for
a period determined by the duty cycle (approximately
VOUT/VIN x 100 %) and the frequency.
The high-side switch turns off, setting the synchronous
rectifier latch and 60 ns later, the rectifier MOSFET turns on.
The low-side switch stays on until the start of the next clock
Document Number: 70190
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cycle in continuous mode, or until the inductor current
becomes positive again, in discontinuous mode. In overcurrent situations, where the inductor current is greater than
the 100 mV current-limit threshold, the high-side latch is
reset and the high-side gate drive is shut off.
During low-current load requirements, the inductor current
will not deliver the 25 mV minimum current threshold. The
Minimum Current comparator signals the PWM to enter
pulse-skipping mode when the threshold has not been
reached. pulse-skipping mode skips pulses to reduce
switching losses, the losses which decrease efficiency the
most at light load. Entering this mode causes the minimum
current comparator to reset the high-side latch at the
beginning of each oscillator cycle.
Soft-Start
To slowly bring up the 3.3 V and 5 V supplies, connect
capacitors from SS3 and SS5 to GND. Asserting ON3 or ON5
starts a 4 A constant current source to charge these
capacitors to 4 V. As the voltage on these pins ramps up, so
does the current limit comparator threshold, to increase the
duty cycle of the MOSFETs to their maximum level. If ON3 or
ON5 are left low, the respective capacitor is discharged to
GND. Leaving the SS3 or SS5 pins open will cause either
controller to reach the terminal over-current level within
10 µs.
Soft start helps prevent current spikes at turn-on and allows
separate supplies to be delayed using external
programmability.
Synchronous rectification is always active when the Si9130
is powered-up, regardless of the operational mode.
Gate-Driver Boost
The high-side N-Channel drive is supplied by a flyingcapacitor boost circuit (see Figure 4). The capacitor takes a
charge from VL and then is connected from gate to source of
the high-side MOSFET to provide gate enhancement. At
power-up, the low-side MOSFET pulls LX_ down to GND
and charges the BST_ capacitor connected to 5 V. During
the second half of the oscillator cycle, the controller drives
the gate of the high-side MOSFET by internally connecting
node BST_ to DH_. This supplies a voltage 5 V higher than
the battery voltage to the gate of the high-side MOSFET.
Oscillations on the gates of the high-side MOSFET in
discontinuous mode are a natural occurrence caused by the
LC network formed by the inductor and stray capacitance at
the LX_ pins. The negative side of the BST_ capacitor is
connected to the LX_ node, so ringing at the inductor is
translated through to the gate drive.
BATTERY
INPUT
VL
VL
BST_
Synchronous Rectifiers
Synchronous rectification replaces the Schottky rectifier with
a MOSFET, which can be controlled to increase the
efficiency of the circuit.
When the high-side MOSFET is switched off, the inductor will
try to maintain its current flow, inverting the inductor’s
polarity. The path of current then becomes the circuit made
of the Schottky diode, inductor and load, which will charge
the output capacitor. The diode has a 0.5 V forward voltage
drop, which contributes a significant amount of power loss,
decreasing efficiency. A low-side switch is placed in parallel
with the Schottky diode and is turned on just after the diode
begins to conduct. Because the rDS(ON) of the MOSFET is
low, the I*R voltage drop will not be as large as the diode,
which increases efficiency.
The low-side rectifier is shut off when the inductor current
drops to zero.
Shoot-through current is the result when both the high-side
and rectifying MOSFETs are turned on at the same time.
Break-before-make timing internal to the Si9130 manages
this potential problem. During the time when neither
MOSFET is on, the Schottky is conducting, so that the body
diode in the low-side MOSFET is not forced to conduct.
Document Number: 70190
S11-0975-Rev. G, 16-May-11
Level
Translator
PWM
DH_
LX_
VL
DL_
Figure 4. Boost Supply for Gate Drivers
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11
This document is subject to change without notice.
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
Si9130
Vishay Siliconix
OPERATIONAL MODES
PWM Mode
The 3.3 V and 5 V Buck controllers operate in continuouscurrent PWM mode when the load demands more than
approximately 25 % of the maximum current (see typical
curves). The duty cycle can be approximated as Duty_Cycle
= VOUT/VIN.
In this mode, the inductor current is continuous; in the first
half of the cycle, the current slopes up when the high-side
MOSFET conducts and then, in the second half, slopes back
down when the inductor is providing energy to the output
capacitor and load. As current enters the inductor in the first
half-cycle, it is also continuing through to the load; hence, the
load is receiving continuous current from the inductor. By
using this method, output ripple is minimized and smaller
form-factor inductors can be used. The output capacitor’s
ESR has the largest effect on output ripple. It is typically
under 50 mV; the worst case condition is under light load with
higher input battery voltage.
Pulse-Skipping Mode
When the load requires less than 25 % of its maximum, the
Si9130 enters a mode which drives the gate for one clock
cycle and skips the majority of the remaining cycles. Pulseskipping mode cuts down on the switching losses, the
dominant power consumer at low current levels.
In the region between pulse-skipping mode and PWM mode,
the controller may transition between the two modes,
delivering spurts of pulses. This may cause the current
waveform to look irregular, but will not overly affect the ripple
voltage. Even in this transitioning mode efficiency will stay
high.
Current Limit
The current through an external resistor, is constantly
monitored to protect against over-current. A low value
resistor is placed in series with the inductor. The voltage
across it is measured by connecting it between CS_ and
FB_. If this voltage is larger than 100 mV, the high-side
MOSFET drive is shut down. Eliminating over-currents
protects the MOSFET, the load and the power source.
Typical values for the sense resistors with a 3 A load will be
25 m.
The SYNC pin can be driven with an external CMOS level
signal with frequency from 240 kHz and 350 kHz to
synchronize to the internal oscillator. Tying SYNC to either
VL or GND sets the frequency to 200 kHz and to REF sets
the frequency to 300 kHz.
Operation at 300 kHz is typically used to minimize output
passive component sizes. Slower switching speeds of
200 kHz may be needed for lower input voltages.
Internal VL and REF
A 5 V linear regulator supplies power to the internal logic
circuitry. The regulator is available for external use from pin
VL, able to source 5 mA. A 4.7 µF capacitor should be
connected between VL and GND. To increase efficiency,
when the 5 V switching supply has voltage greater than
4.5 V, VL is internally switched over to the output of the 5 V
switching supply and the linear regulator is turned off.
The 5 V linear regulator provides power to the internal 3.3 V
bandgap reference (REF). The 3.3 V reference can supply
5 mA to an external load, connected to pin REF. Between
REF and GND connect a capacitor, 0.22 µF plus 1 µF per mA
of load current. The switching outputs will vary with the
reference; therefore, placing a load on the REF pin will cause
the main outputs to decrease slightly, within the specified
regulation tolerance.
VL and REF supplies stay on as long as V+ is greater than
4.5 V, even if the switching supplies are not enabled. This
feature is necessary when using the micropower regulators
to keep memory alive during shutdown.
Both linear regulators can be connected to their respective
switching supply outputs. For example, REF would be tied to
the output of the 3.3 V and VL to 5 V. This will keep the main
supplies up in standby mode, provided that each load current
in shutdown is not larger than 5 mA.
Fault Protection
The 3.3 V and 5 V switching controllers are shut down when
one of the linear regulators drops below 85 % of its nominal
value;
that
is,
shut
down
will
occur
when
VL < 4.0 V or REF < 2.8 V.
Oscillator and SYNC
There are two ways to set the Si9130 oscillator frequency: by
using an external SYNC signal, or using the internal
oscillator.
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Document Number: 70190
S11-0975-Rev. G, 16-May-11
This document is subject to change without notice.
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
Si9130
Vishay Siliconix
DESIGN CONSIDERATIONS
Inductor Design
Three specifications are required for inductor design:
inductance (L), peak inductor current (ILPEAK), and coil
resistance (RL). The equation for computing inductance is:
L
V OUT VIN(MAX)- VOUT
VIN(MAX) (f) IOUT (LIR)
Where: VOUT = Output voltage (3.3 V or 5 V);
VIN(MAX) = Maximum input voltage (V);
f = Switching frequency, normally 300 kHz;
IOUT = Maximum dc load current (A);
LIR = Ratio of inductor peak-to-peak ac current to average dc
load current, typically 0.3.
When LIR is higher, smaller inductance values are
acceptable, at the expense of increased ripple and higher
losses.
The peak inductor current (ILPEAK) is equal to the steadystate load current (IOUT) plus one half of the peak-to-peak ac
current (ILPP). Typically, a designer will select the ac inductor
current to be 30 % of the steady-state current, which gives
ILPEAK equal to 1.15 times IOUT.
The equation for computing peak inductor current is:
ILPEAK
IOUT +
VOUT VIN(MAX) - VOUT
(2)(f)(L) VIN(MAX)
Where: CF = Output filter capacitance (F)
VREF = Reference voltage, 3.3 V;
VOUT = Output voltage, 3.3 V or 5 V;
RCS = Sense resistor ();
GBWP = Gain-bandwidth product, 60 kHz;
ESRCF = Output filter capacitor ESR ().
Both minimum capacitance and maximum ESR
requirements must be met. In order to get the low ESR, a
capacitance value of two to three times greater than the
required minimum may be necessary.
The equation for output ripple in continuous current mode is:
VOUT(RPL)
ILPP(MAX) x
ESRCF +
1
2 x f x CF
The equations for capacitive and resistive components of the
ripple in pulse-skipping mode are:
VOUT(RPL)(C)
VOUT(RPL)(R)
(4) 10- 4 (L)
RCS 2 C F
x
1 +
1
VOUT VIN - VOUT Volts
(0.02) ESRCF
Volts
R CS
The total ripple, VOUT(RPL), can be approximated as follows:
if VOUT(RPL)(R) < 0.5 VOUT(RPL)(C),
then VOUT(RPL) = VOUT(RPL)(C),
otherwise, VOUT(RPL) = 0.5 VOUT(RPL)(C) +
VOUT(RPL)(R).
OUTPUT CAPACITORS
The output capacitors determine loop stability and ripple
voltage at the output. In order to maintain stability, minimum
capacitance and maximum ESR requirements must be met
according to the following equations:
CF
VREF
VOUT RCS (2)(π)(GBWP)
and,
ESRCF
Lower Voltage Input
The application circuit shown here can be easily modified to
work with 5.5 V to 12 V input voltages. Oscillation frequency
should be set at 200 kHz and increase the output
capacitance to 660 µF on the 5 V output to maintain stable
performance up to 2 A of load current. Operation on the
3.3 V supply will not be affected by this reduced input
voltage.
VOUT RCS
VREF
Vishay Siliconix maintains worldwide manufacturing capability. Products may be manufactured at one of several qualified locations. Reliability data for Silicon Technology and Package Reliability represent a composite of all qualified locations. For related documents such as package/tape drawings, part marking, and reliability
data, see www.vishay.com/ppg?70190.
Document Number: 70190
S11-0975-Rev. G, 16-May-11
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13
This document is subject to change without notice.
THE PRODUCTS DESCRIBED HEREIN AND THIS DOCUMENT ARE SUBJECT TO SPECIFIC DISCLAIMERS, SET FORTH AT www.vishay.com/doc?91000
Package Information
Vishay Siliconix
SSOP: 28-LEAD (5.3 MM) (POWER IC ONLY)
28
15
−B−
E1
1
E
14
−A−
D
e
0.25
GAUGE PLANE
R
c
A2 A
A1
−C−
0.076
L
SEATING PLANE
C
b
0.12 M
A
B
C
SEATING PLANE
L1
S
MILLIMETERS
Dim
A
A1
A2
b
c
D
E
E1
e
L
L1
R
Min
Nom
Max
1.73
1.88
1.99
0.05
0.13
0.21
1.68
1.75
1.78
0.25
0.30
0.38
0.09
0.15
0.20
10.07
10.20
10.33
7.60
7.80
8.00
5.20
5.30
5.40
0.65 BSC
0.63
0.75
0.95
1.25 BSC
0.09
0.15
−−−
0_
4_
8_
ECN: S-40080—Rev. A, 02-Feb-04
DWG: 5915
Document Number: 72810
28-Jan-04
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Document Number: 91000
Revision: 11-Mar-11
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