SI9102 Datasheet, PDF (5/7 Pages) Vishay Siliconix – 3-W High-Voltage Switchmode Regulator

Si9102
Vishay Siliconix
PIN CONFIGURATIONS
PDIP-14
1
14
2
13
3
12
4
11
5
10
6
9
7
8
Top View
PLCC-20
3 2 1 20 19
4
18
5
17
6
16
7
15
8
14
PIN DESCRIPTION
Pin
Function
14-Pin DIP
20-Pin PLCC*
BIAS
1
2
+V_IN
2
3
DRAIN
3
5
SOURCE
4
7
−V_IN
5
8
V_CC
6
9
OSC OUT
7
10
OSC IN
8
11
DISCHARGE
9
12
V_REF
10
14
SHUTDOWN
11
16
RESET
12
17
COMP
13
18
FB
14
20
*Pins 1, 4, 6, 13, 15, and 19 = N/C
9 10 11 12 13
Top View
Standard
Part Number
Si9102DJ02
Si9102DN02
ORDERING INFORMATION
Lead (Pb)-Free Temperature
Part Number
Range
Si9102DJ02—E3
Si9102N02—E3
−40 to 85 _C
Package
PDIP-14
PLCC-20
DETAILED DESCRIPTION
Pre-Regulator/Start-Up Section
Due to the low quiescent current requirement of the Si9102
control circuitry, bias power can be supplied from the
unregulated input power source, from an external regulated
low-voltage supply, or from an auxiliary “bootstrap” winding on
the output inductor or transformer.
When power is first applied during start-up, +V_IN will draw a
constant current. The magnitude of this current is determined
by a high-voltage depletion MOSFET device which is
connected between +V_IN and V_CC. This start-up circuitry
provides initial power to the IC by charging an external bypass
capacitance connected to the V_CC pin. The constant current is
Document Number: 70001
S-42040—Rev. G, 15-Nov-04
disabled when V_CC exceeds 9.4 V. If V_CC is not forced to
exceed the 9.4-V threshold, then V_CC will be regulated to a
nominal value of 9.4 V by the pre-regulator circuit.
As the supply voltage rises toward the normal operating
conditions, an internal undervoltage (UV) lockout circuit keeps
the output MOSFET disabled until V_CC exceeds the
undervoltage lockout threshold (typically 8.8-V). This
guarantees that the control logic will be functioning properly
and that sufficient gate drive voltage is available before the
MOSFET turns on. The design of the IC is such that the
undervoltage lockout threshold will not exceed the
pre-regulator turn-off voltage. Power dissipation can be
minimized by providing an external power source to V_CC such
that the constant current source is always disabled.
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