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EST7502B PC Power Supply PWM with Supervisor

GENERAL DESCRIPTION
The EST7502B 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 1 16 VADJ
V5 2 15 OPNEGIN
V12 3 14 OPOUT
PT 4 13 VCC
GND 5 12 DET
RT 6 11 PG
C1 7 10 SS
C2 8 9 REM

ORDERING INFORMATION
ORDER NUMBER Package Shipping Top Marking
EST7502B DIP 16

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EST7502B PC Power Supply PWM with Supervisor

PIN DESCRIPTION

Pin No. Pin Name TYPE FUNCTION

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.
REM=”low” that means the main SMPS is turned-on.
REM=”high”, the main SMPS is turned-off.
10 SS O Soft start function set by external capacitor.
11 PG O Power good signal.
PG= ”high” means “power good”.
PG= ”low” means “power fail”.
12 DET I Extra protection input.
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.

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EST7502B PC Power Supply PWM with Supervisor

BLOCK DIAGRAM

- UV
[1] V33 +

- UV
[2] V5 +

110us
- UV UVP
[3] V12 +
280ms delay

IN OUT
CLR
- OV
+ S Q
510us
OVP
- OV R
+

- OV
+

- OV
+

[4] PT -
+
0.62V

QOUT 5K
[11]
280ms delay PG

IN OUT

36mS REMONF
[9] REM
Vss
Delay
4.5mS REMON
[10]

Delay SS
[12] DET -
+
0.62V

OSC
[6] C1 [7]
RT CLR
PWM CONTROL D Q
PWMCMP
ERROR AMP
[16] VADJ + - C QN
+
[15] OPNEGIN - C2 [8]
2.45V

+
[14] OPOUT -
DETCMP
SOFT_START CONTROLLER

ABSOLUTE MAXIMUM RATINGS, VCC=5.5V

CHARACTERISTICS SYMBOL VALUE Unit
Supply voltage VCC 5.5 V
Drain output voltage Vcc1, Vcc2 5.5 V
Drain output current Icc1, Icc2 200 mA
Power dissipation Pd 200 mW
Operating temperature Topr -20 ~ +85 ℃
Storage temperature Tstg -65 ~ +150 ℃

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EST7502B PC Power Supply PWM with Supervisor

ELECTRICALCHARACTERISTICS,TA=25℃, VCC=5V,
CHARACTERISTICS SYMBOL TEST CONDITION Min. Typ. Max. Unit
ERROR AMP SECTION
OPEN LOOP VOLTAGE GAIN 0.5V ~ 3.5V 75 85 dB
CROSS OVER POINT 0dB 1000 KHZ
OPNEG BIAS VOLTAGE OPNEG OPEN 2.40 2.45 2.50 V
POWER SUPPLY REJECTION RATIO PSRR 45 dB
OUTPUT SECTION
OUTPUT SATURATION VOLTAGE Vdssat Id=200mA 1.1 1.3 V
DRAIN OFF-STATE CURRENT Idoff Vcc=Vd=Vs=0V 2 10 uA
RISING TIME Tr 100 200 ns
FALLING TIME Tf 50 200 ns
PROTECTION SECTION
OVER VOLTAGE PROTECTION V33 3.8 4.1 4.3 V
（OVP） V5 5.8 6.2 6.6 V
V12 4.4 4.6 4.9 V
PT 1.23 1.28 1.33 V
Tg.ov 510 us
UNDER VOLTAGE PROTECTION V33 1.7 1.9 2.2 V
（UVP） V5 2.7 3.0 3.3 V
V12 2.1 2.4 2.7 V
Tg.uv 120 us
UVP DISABLE VOLTAGE PT 0.55 0.62 0.68 V
UVP DELAY TIME Td.uvp 100 280 380 ms
REMOTE ON/OFF SECTION
REM HIGH INPUT VOLTAGE Vremh 1.8 V
REM LOW INPUT VOLTAGE Vreml 0.7 V
REM PULL HIGH VOLTAGE Vremo 2.0 5.25 V
REM DELAY TIME Td on/off 40 ms
POWER GOOD SECTION
DETECT INPUT VOLTAGE Vdet 0.68 V
PG OUTPUT PULL–UP RESISTOR Rpup, pg 5 KΩ
PG OUTPUT LOAD RESISTOR Rpg 0.5 1 2 KΩ
PG DELAY TIME 180 280 380 ms
SINK CURRENT Ipg.sink VPG=0.2V 10 mA
SOFT START SECTION
SINK CURRENT OF SS Iss.sink RT=100KΩ 15 uA
SOURCE CURRENT OF SS Iss.source 310 uA
VCC Under Voltage Lockout(UVLO)
Start-up voltage 4.2 V
TOTAL DEVICE
STANDBY SUPPLY CURRENT Icc REM=5V 10 20 mA
OSCILLATION SECTION
OSCILLATION FREQUENCY Fosc RT=100KΩ 70 75 80 KHZ

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EST7502B PC Power Supply PWM with Supervisor

APPLICATION NOTE

1. Input impedance:

Pin No. Pin Name Input impedance

1 V33 52KΩ
2 V5 81KΩ
3 V12 52KΩ
4 PT 24 KΩ+4.6 KΩ

2. Sawtooth OSC. Function:

3.REMOTE ON/OFF：

REM

REMONF trem trem

REMON toff toff

SS

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EST7502B PC Power Supply PWM with Supervisor

4. Under Voltage Protection Delay Time：

REM

REMON

td,uvp
UVP

5. Pulse Width Modulation Block：

The output pulse width modulation is generated by comparison of the saw–tooth
waveform from the capacitor CT to the feedback of the voltage.
Therefore, an increase in feedback control signal amplitude cause a linear decrease of the
output pulse width. Also, the SS(DTC and Soft-Start) limits the output pulse width. The
timing diagram is shown as below:

PWM OUT
CT
DTC

FF-CLK

FF-Q

FF-QN

C1

C2

6. The function of “PT”:

This signal is prepared for extra OVP/OPP (VPT > 1.28V) or another Disable Under
Voltage Protection function (VPT < 0.62V)

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EST7502B PC Power Supply PWM with Supervisor

7. Reference Application Circuit:

8. In some application power system, adding an external resistor (R9) could reduce the peak
value spike from the environments to pin 9 (REM) and avoid pin 9 (REM ) damaged by the
external noise.

EXTERNAL DIMENSIONS
DIM INCHES MILLIMETERS
MIN MAX MIN MAX
A 0.740 0.770 18.80 19.55
B 0.250 0.270 6.35 6.85
C 0.145 0.175 3.69 4.44
D 0.015 0.021 0.39 0.53
F 0.040 0.070 1.02 1.78
G 0.100BSC 2.54BSC
H 0.050BSC 1.27BSC
J 0.008 0.015 0.21 0.38
K 0.110 0.130 2.80 3.30
L 0.295 0.305 7.50 7.74
M 0° 10° 0° 10°
S 0.020 0.040 0.51 1.01

DIP-16 Outline Dimensions

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