SI786 Vishay, SI786 Datasheet - Page 7

• Manufacturer Part Number: SI786
• Description: Dual-output Power-supply Controller
• Manufacturer: Vishay

Document Number: 70189
S-40807—Rev. J, 26-Apr-04
PIN DESCRIPTION AND ORDERING INFORMATION
PIN DESCRIPTION
Pin
10
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
27
28
11
1
2
3
4
5
6
7
8
9
Symbol
SHDN
PGND
SYNC
BST
BST
GND
REF
CS
ON
ON
CS
DH
DH
SS
SS
LX
DL
FB
DL
LX
FB
D
D
V
Q
Q
V
V+
H
L
1
2
2
1
5
3
3
5
5
5
3
3
3
3
5
5
5
3
5
3
Current-sense input for 3.3-V Buck controller—this pins over current threshold is 100 mV with respect to FB
Soft-start input for 3.3 V. Connect capacitor from SS
ON/OFF logic input disables the 3.3-V Buck controller. Connect directly to V
Comparator #1 noninverting input, threshold = 1.650 V. Comparator #1 output = Q1. Connect to GND if unused.
Comparator #2 noninverting input (see D
External bias supply-voltage input for comparators #1 and #2.
Comparator #2 output. Sources 20 mA from V
voltage.
Comparator #1 output (see Q
Analog ground.
3.3-V reference output. Supplies external loads up to 5 mA.
Oscillator control/synchronization input. Connect capacitor to GND, 1-mF/mA output or 0.22 mF 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.
Shutdown logic input, active low. Connect to V
ing connection to SHDN.
ON/OFF logic input disables the 5-V Buck Controller. Connect to V
Soft-start control input for 5 V Buck controller. Connect capacitor from SS
Current-sense input for 5 V Buck controller—this pins over current threshold is 100 mV referenced to FB
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. V
Supply voltage input.
Gate-drive output for the 3.3-V supply rectifying n-channel MOSFET.
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.
SHDN
SYNC
GND
REF
ON
ON
CS
SS
SS
V
Q
Q
D
D
H
3
3
3
1
2
2
1
5
5
2
).
10
12
13
14
11
1
2
3
4
5
6
7
8
9
SSOP-28
1
Top View
).
H
L
when D
for automatic turn-on. The 5-V V
3
to GND.
28
27
26
25
24
23
22
21
20
19
18
17
16
15
2
Description
is high. Sinks 500 mA to GND when D
FB
DH
LX
BST
DL
V+
V
FB
PGND
DL
BST
LX
DH
CS
L
3
3
3
5
5
5
3
5
5
3
5
L
for automatic turn-on.
5
to GND.
L
for automatic turn-on.
L
L
remains on with valid voltage at V+.
supply will not be disabled in shutdown allow-
2
Vishay Siliconix
is low regardless of V
3
.
3
.
www.vishay.com
Si786
H
input
7