SI786 Datasheet, PDF (7/14 Pages) Vishay Siliconix – Dual-Output Power-Supply Controller

PIN DESCRIPTION AND ORDERING INFORMATION
Si786
Vishay Siliconix
CS₃ 1
SS₃ 2
ON₃ 3
D₁ 4
D₂ 5
V_H 6
Q₂ 7
Q₁ 8
GND 9
REF 10
SYNC 11
SHDN 12
ON₅ 13
SS₅ 14
28 FB₃
27 DH₃
26 LX₃
25 BST₃
24 DL₃
23 V+
SSOP-28 ^{22 VL}
21 FB₅
20 PGND
19 DL₅
18 BST₅
17 LX₅
16 DH₅
15 CS₅
Top View
PIN DESCRIPTION
Pin
Symbol
Description
1
CS₃
Current-sense input for 3.3-V Buck controller—this pins over current threshold is 100 mV with respect to FB₃.
2
SS₃
Soft-start input for 3.3 V. Connect capacitor from SS₃ to GND.
3
ON₃
ON/OFF logic input disables the 3.3-V Buck controller. Connect directly to V_L for automatic turn-on.
4
D₁
Comparator #1 noninverting input, threshold = 1.650 V. Comparator #1 output = Q1. Connect to GND if unused.
5
D₂
Comparator #2 noninverting input (see D₁).
6
V_H
External bias supply-voltage input for comparators #1 and #2.
7
Q₂
Comparator #2 output. Sources 20 mA from V_H when D₂ is high. Sinks 500 mA to GND when D₂ is low regardless of V_H input
voltage.
8
Q₁
Comparator #1 output (see Q₂).
9
GND
Analog ground.
10
REF
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
11
SYNC
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 V_L for automatic turn-on. The 5-V V_L supply will not be disabled in shutdown allow-
ing connection to SHDN.
13
ON₅
ON/OFF logic input disables the 5-V Buck Controller. Connect to V_L for automatic turn-on.
14
SS₅
Soft-start control input for 5 V Buck controller. Connect capacitor from SS₅ to GND.
15
CS₅
Current-sense input for 5 V Buck controller—this pins over current threshold is 100 mV referenced to FB₃.
16
DH₅
Gate-drive output for the 5-V supply high-side n-channel MOSFET.
17
LX₅
Inductor connection for the 5-V supply.
18
BST₅
Boost capacitor connection for the 5-V supply.
19
DL₅
Gate-drive output for the 5-V supply rectifying n-channel MOSFET.
20
PGND
Power Ground.
21
FB₅
Feedback input for the 5-V Buck controller.
22
V_L
5-V logic supply voltage for internal circuitry—able to source 5-mA external loads. V_L remains on with valid voltage at V+.
23
V+
Supply voltage input.
24
DL₃
Gate-drive output for the 3.3-V supply rectifying n-channel MOSFET.
25
BST₃
Boost capacitor connection for the 3.3-V supply.
26
LX₃
Inductor connection for the 3.3-V supply.
27
DH₃
Gate-drive output for the 3.3-V supply high-side n-channel MOSFET.
28
FB₃
Feedback input for the 3.3-V Buck controller.
Document Number: 70189
S-40807—Rev. J, 26-Apr-04
www.vishay.com
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