SI9102_07 Datasheet, PDF (5/10 Pages) Vishay Siliconix – 3-W High-Voltage Switchmode Regulator

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
9 10 11 12 13
Top View
Si9102
Vishay Siliconix
PIN DESCRIPTION
Function
14-Pin DIP
BIAS
1
+ V_IN
2
DRAIN
3
SOURCE
4
- V_IN
5
V_CC
6
OSC OUT
7
OSC IN
8
DISCHARGE
9
V_REF
10
SHUTDOWN
11
RESET
12
COMP
13
FB
14
*Pins 1, 4, 6, 13, 15, and 19 = N/C
Pin
20-Pin PLCC*
2
3
5
7
8
9
10
11
12
14
16
17
18
20
ORDERING INFORMATION
Standard
Part Number
Lead (Pb)-free
Part Number
Temperature
Range
Package
Si9102DJ02
Si9102DJ02-E3
PDIP-14
Si9102DN02 Si9102DN02-E3
Si9102DN02-T1 Si9102DN02-T1-E3
(With Tape
(With Tape
and Reel)
and Reel)
- 40 to 85 °C
PLCC-20
DETAIL 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 unreg-
ulated 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 con-
nected between + V_IN and V_CC. This start-up circuitry pro-
vides initial power to the IC by charging an external bypass
capacitance connected to the V_CC pin. The constant current
is 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.
Document Number: 70001
S-70497-Rev. H, 19-Mar-07
As the supply voltage rises toward the normal operating con-
ditions, an internal undervoltage (UV) lockout circuit keeps
the output MOSFET disabled until V_CC exceeds the under-
voltage lockout threshold (typically 8.8 V). This guarantees
that the control logic will be functioning properly and that suf-
ficient 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.
Note: During start-up or when V_CC drops below 9.4 V the
start-up circuit is capable of sourcing up to 20 mA. This may
lead to a high level of power dissipation in the IC (for a 48 V
input, approximately 1 W). Excessive start-up time caused
by external loading of the V_CC supply can result in device
damage. Figure 4 gives the typical pre-regulator current at
start-up as a function of input voltage.
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