Weltrend WT7520 Schematic [ru]
偉詮電子股份有限公司
Weltrend Semiconductor, Inc.
WT7520
PC POWER SUPPLY PWM SUPERVISOR
Data Sheet
REV. 0.9
February 21, 2005
The information in this document is subject to change without notice.
Weltrend Semiconductor, Inc. All Rights Reserved.
新竹市科學工業園區工業東九路 24 號 2 樓
2F, No. 24, Industry E. 9th RD., Science-Based Industrial Park, Hsin-Chu, Taiwan
TEL:886-3-5780241 FAX:886-3-5794278.5770419
Email:support@weltrend.com.tw
WT7520
15 14 13 12 11 10 9 1 2 3 4 5 6 7
7520
Data Sheet Rev. 0.90
GENERAL DESCRIPTION
The WT7520 is a pulse–width modulation (PWM) control circuit with complete protection circuits for used
in the SMPS (Switched Mode Power Supply). It contains various functions, which are Over Voltage
Protection, Under Voltage Protection, Power Good Output (PGO), Remote On/Off control and etc. It can
minimize external components of switching power supply systems in personal computer.
Over Voltage Protection (OVP) monitors 3.3V, 5V, 12V and PT input voltage level. Under Voltage
Protection (UVP) monitors 3.3V, 5V and 12V input voltage level. Power Good Output monitors the voltage
level of power supply.
FEATURES
• Complete PWM Control and Protection Circuitry
• Over Voltage Protection for 3.3V / 5V / 12V / PT
• Under Voltage Protection for 3.3V / 5V / 12V
• 280ms PG Time Delay
• Power Good Output is Open Drain Output
• PWM Control Output are Open Drain Output
• 280 mS Time Delay for UVP
• Remote ON/OFF function De–bounce Time
• Soft-Start function built-in
• 16–Pin Dual In–line Package
PIN CONFIGURATION
V33
V5
V12
PT
GND
RT
C1
C2
Ordering Number Package Type
WT7520 DIP 16
16
8
VADJ
OPNEGIN
OPOUT
VCC
DET
PG
SS
REM
Weltrend Semiconductor, Inc.
Page 2
WT7520
Data Sheet Rev. 0.90
PIN DESCRIPTION
Pin No.
1 V33 I OVP/UVP input FOR 3.3V .
2 V5 I OVP/UVP input for 5V.
3 V12 I OVP/UVP input for 12V.
4 PT I Extra OVP protection input.
5 GND P Ground.
6 RT O Oscillation frequency set by external resistor .
7 C1 O PWM open drain output 1.
8 C2 O PWM open drain output 2.
9 REM I Remote on/off input.
10 SS
11 PG O Power good signal.
12 DET
13 VCC P Supply voltage.
14 OPOUT O OP compensation output.
15 OPNEGIN I OP compensation negative input.
16 VADJ I OP compensation positive input , feedback voltage sense input.
Pin Name TYPE FUNCTION
REM=”low” that means the main SMPS is turned-on.
REM=”high”, the main SMPS is turned-off.
O Soft start function set by external capacitor.
PG = ”high” means “power good”.
PG = ”low” means “power fail”.
I Extra protection input.
*The difference between WT7905 and WT7520
ITEM WT7905 WT7520
Pin-6
(PWM frequency)
Pin-10 TPG; external capacitor
OVP-3.3V,5V,12V 100us (Typ.) 510us (Typ.)
UVP-3.3V,5V,12V 100us (Typ.) 110us (Typ.)
Soft-Start function Set by internal circuit Set by external capacitor
Pin-4
(PT)
CT; external capacitor RT; external resistor
(ex. 120kΩ)
SS; external capacitor
(PG delay-time function)
(Soft-start function)
(Pin-10:SS)
PT default 0.8V (with internal
voltage divided resistors)
PT default 0.8V. (with internal
voltage divided resistors)
(24K+4.6K)
Weltrend Semiconductor, Inc.
Page 3
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