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부품번호 | CS403 기능 |
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기능 | 5V/ 750mA Linear Regulator with RESET | ||
제조업체 | Cherry Semiconductor Corporation | ||
로고 | |||
전체 6 페이지수
CS3972
1.25A High Efficiency Switching Regulator
Description
The CS3972 is a 1.25A, 60V, current
mode, high efficiency, switching
regulator circuit. It can be config-
ured in buck, boost, forward, iso-
lated and non-isolated topologies,
using a single-ended switch.
The IC contains a 1.25A high effi-
ciency output switch, precision
bandgap reference, voltage regula-
tor, error amplifier, oscillator, con-
trol, and protection circuitry.
Output transistor efficiency is
achieved by keeping the switch in
quasi-saturation when it is on. This
minimizes the switch turn-off
delay time and power dissipation,
an important consideration for
applications with wide ranging
loads.
The precision reference is internally
trimmed to 1.24V, while the oscilla-
tor frequency is internally trimmed
to 40kHz. The on board 2.3V regu-
lator powers the internal circuitry.
By keeping the voltage regulator at
2.3V, the IC is able to operate down
to 3V and maintain a constant input
supply current of 6mA(typ).
Synchronization mode is achieved
by applying a pulsating VC voltage
of less than 0.2V with a duration of
about 0.5µs to VC pin. The switch-
ing frequency can be adjusted from
50kHz to 70kHz. The IC's synchro-
nization mode is set externally.
Protection circuitry includes a vari-
able current limit with external
voltage clamp, under-voltage and
over-temperature protection.
Block Diagram
VIN
2.3V
Reg
40kHz
OSC
Logic
Output
Protection
Driver
VSW
1.25A,
75V
Switch
Features
s S75wViMtcAhX, 2APEAK Internal
s 3V to 60V Input Voltage
Range
s 6mA Input Supply
Current
s 1.24V Precision Reference
s 40kHz Switching
Frequency
s Variable Current Limit
with External Voltage
Clamp
s Under-Voltage Protection
s Over-Temperature
Protection
s External Synchronization
Package Options
16L SO Wide
NC 1
VC
VFB
NC
NC
NC
NC
NC
Gnd
NC
E2
VSW
NC
E1
NC
VIN
COMP
+-
VC
VFB -
Error
Amp
+
1.24V
Ref
+
Current
Amp
-
0.22Ω
0.22Ω
*Always connect E1 to Ground Pin on DIP package. Both emitters are tied to ground on TO-220 Package.
Rev. 6/23/99
1
8L PDIP
5L TO-220
Tab (Gnd)
E2*
E1*
Gnd
Gnd 1
VC
VFB
NC
E2
VSW
E1
VIN
1
1 VC
2 VFB
3 Gnd
4 VSW
5 VIN
Cherry Semiconductor Corporation
2000 South County Trail, East Greenwich, RI 02818
Tel: (401)885-3600 Fax: (401)885-5786
Email: [email protected]
Web Site: www.cherry-semi.com
A Company
®
Circuit Description
The CS3972 has an on board, high current NPN transistor
in its output stage. The output transistor is switched on
every 25µs by the on board 40 kHz oscillator. The output
is switched off as soon as the output current reaches a
dynamically controlled level. That level is determined by
three factors: the current drawn by the load, the input
voltage, and the output voltage. This control scheme has
several benefits. The IC reacts quickly to overvoltage and
short circuit conditions and it is less sensitive to input
voltage fluctuation.
Current drawn by the load influences when the output
stage turns off. The voltage across the internal high preci-
sion resistor (0.11Ω) in the emitter of the output transistor
generating the input to the current sensing amplifier. The
output of the current sensing amplifier provides one of the
inputs to the comparator.
The other input to the comparator connected to the out-
put of the error amplifier whose inverting input is con-
nected to the output voltage through the feedback circuit-
ry while its noninverting input is set to an internal refer-
ence voltage of 1.24V. When the current sensing amplifier
output exceeds the error amplifier output, the comparator
switches off, triggering the logic which turns off the out-
put stage.
All on board amplifier, logic and protection circuitry uses
the internal 2.3V reference to minimize quiescent current
drain (6mA) and permits IC operation down to 3V.
The anti-saturation circuitry minimizes output switch
turn off time and power dissipation, by keeping the
power NPN at the edge of saturation.
VIN L1
Application Diagrams
D1
VOUT
VIN
Q1
L1 VOUT
R2 R1
R3
VSW
VIN
CS3972
VFB
+
C1
VC
R1
Gnd
C2
(1.24V)
+
C3
R3
+
C1
VSW
VIN
CS3972
VFB
VC Gnd
R2
C2
D1
(1.24V)
+
C3
R4
Figure 1: Boost Regulator
Figure 2: Buck Regulator with the External Switch
VIN TR1
C4
R1
C1
VSW
VIN
VFB
CS3972
+
C2
VC
R2
Gnd
C3
VOUT1
+
C5
VOUT2
+
C6
R4
(1.24V)
R5
+VIN
D1
TR1
L1
D2
VOUT
+
C3
D3
+
C2
–VIN
VSW
VIN
CS3972
R1
VC Gnd
VFB
R2
C3
1/2
OC1
D1 R3
1/2 R4
OC1
R5
C5
R6
C4
U1
R7
Figure 3: Flyback Multiple Output Regulator
Figure 4: Isolated Forward Regulator
4
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구매 문의 | 일반 IC 문의 : 샘플 및 소량 구매 ----------------------------------------------------------------------- IGBT, TR 모듈, SCR 및 다이오드 모듈을 포함한 광범위한 전력 반도체를 판매합니다. 전력 반도체 전문업체 상호 : 아이지 인터내셔날 사이트 방문 : [ 홈페이지 ] [ 블로그 1 ] [ 블로그 2 ] |
부품번호 | 상세설명 및 기능 | 제조사 |
CS400 | High Voltage Bridge Rectifiers | High Voltage Power Solutions |
CS403 | 5V/ 750mA Linear Regulator with RESET | Cherry Semiconductor Corporation |
DataSheet.kr | 2020 | 연락처 | 링크모음 | 검색 | 사이트맵 |