S-816 Datasheet, PDF (13/24 Pages) Seiko Instruments Inc – EXTERNAL TRANSISTOR TYPE CMOS VOLTAGE REGULATOR

Rev.5.1_00
EXTERNAL TRANSISTOR TYPE CMOS VOLTAGE REGULATOR
S-816 Series
„ Application Circuits
1. Overcurrent Protection Circuit
Figure 11 shows a sample of overcurrent protection implemented with an external circuit connected.
The internal overcurrent protection function of the S-816 Series is designed to detect the sink current
(base current of the PNP transistor) at the EXT pin, therefore it may not be able to protect the external
PNP transistor from collector overcurrents caused by an EXT-GND short-circuiting or other phenomenon
occurring outside the IC.
This sample circuit activates the regulator intermittently against collector overcurrents, thereby
suppressing the heat generation of the external PNP transistor.
The duty of the on-time and off-time of the intermittent operation can be regulated through an external
component.
R_S
0.5 Ω
2SA1213Y
OUT
Tr1
V_IN
+ _CIN
R₂
− ^{10 µF} _{2 kΩ}
R₄
2 kΩ
R₁
100 kΩ
VIN
ON/OFF
EXT
VOUT
S-816 Series
+ _CL
− ^{10 µF}
R₃
C₂
2 kΩ 0.22 µF
Tr2
C₁
0.22 µF
VSS
Figure 11
Caution The above connection diagram and constant will not guarantee successful operation.
Perform through evaluation using the actual application to set the constant.
S-816A30AMC (VIN =4 V)
S-816A30AMC (VIN =4 V)
1A
Load Current
(0.5 A/div)
0A
1A
Load Current
(0.5 A/div)
0A
2V
VON/OFF
(1 V/div)
0V
2V
VON/OFF
(1 V/div)
0V
t (2 ms/div)
t (100 µs/div)
Figure 12 Output Current Waveforms during Intermittent Operation Prompted by Load Short-Circuiting
Seiko Instruments Inc.
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