Fairchild UC3525A service manual
查询UC3525供应商
UC3525A
SMPS Controller
www.fairchildsemi.com
Features
•5V ± 1% Reference
• Oscillator Sync terminal
• Internal Soft Start
• Deadtime Control
• Under-Voltage Lockout
Internal Block Diagram
Description
UC3525A is a m onolithic integrated ci rcuit that Included
all of the control circuit necessary for a pulse width modulating regulator. There are a voltage reference, an error amplifier, a pulse width modulator, an oscillator, under-voltage
lockout, soft start circuit, and output drivers in the chip.
16-DIP
1
©2000 Fairchild Semiconductor International
Rev. 5.0
UC3525A
Absolute Maximum Ratings
Parameter Symbol Value Unit
Supply Voltage V
Collector Supply Voltage V
Output Current, Sink or Source I
Reference Output Current I
Oscillator Charging Current I
Power Dissipation (T
= 25°C) P
A
REF
CHG(OSC)
Operating Temperature T
Storage Temperature T
Lead Temperature (Soldering, 10 sec) T
LEAD
Electrical Characteristics
(VCC = 20V, TA = -30°C to + 85°C, unless otherwise specified)
Parameter Symbol Conditions Min. Typ. Max. Unit
REFERENCE SECTION
Reference Output Voltage V
Line Regulation ∆V
Load Regulation ∆V
Short Circuit Output Current I
Total Output Variation (Note 1) ∆V
Temperature Stability (Note 1) ST
REF
REF
REF
SC
REF
T
Long Term Stability (Note 1) ST T
OSCILLATOR SECTION
Initial Accuracy (Note 1, 2) ACCUR T
Frequency Change With Voltage ∆f/∆V
Maximum Frequency f
Minimum Frequency f
Clock Amplitude (Note 1, 2) V
Clock Width (Note 1, 2) t
Sync Threshold V
Sync Input Current I
(MAX)
(MIN)
(CLK)
W(CLK)
TH(SYNC)
I(SYNC)
TJ = 25°C 5.0 5.1 5.2 V
VCC = 8 to 35V - 9 20 mV
I
= 0 to 20mA - 20 50 mV
REF
V
REF
Line, Load and Temperature 4.95 - 5.25 V
= 125°C ,1 KHR
J
= 25°C-± 3 ± 6%
J
V
CC
= 8 to 35V (Note 1, 2) - ± 0.8 ± 2%
CC
RT = 2KΩ, CT = 470pF 400 430 - KHz
RT = 200KΩ, CT = 0.1uF - 60 120 Hz
TJ = 25°C0.30.61µs
Sync = 3.5V - 1.3 2.5 mA
CC
C
O
40 V
40 V
500 mA
50 mA
5mA
D
OPR
STG
1000 m/W
0 ~ +70 °C
-65 ~ +150 °C
+300 °C
= 0, TJ = 25°C - 80 100 mA
- -2050mV
S
-2050mV
- 34- V
- 1.222.8V
2
Electrical Characteristics
(VCC = 20V, TA = 0 to +85°C, unless otherwise specified)
Parameter Symbol Conditions Min. Typ. Max. Unit
ERROR AMPLIFIER SECTION (V
Input Offset Voltage V
Input Bias Current I
Input Offset Current I
Open Loop Voltage Gain G
Common Mode Rejection Ratio CMRR V
Power Supply Rejection Ratio PSRR V
PWM COMPARATOR SECTION
Minimum Duty Cycle D
Maximum Duty Cycle D
Input Threshold Voltage (Note 2) V
Input Threshold Voltage (Note 2) V
SOFT-START SECTION
Soft Start Current I
Soft Start Low Level Voltage V
Shutdown Threshold Voltage V
Shutdown Input Current I
OUTPUT SECTION
Low Output Voltage I V
Low Output Voltage II V
High Output Voltage I V
High Output Voltage II V
Under Voltage Lockout V
Collector Leakage Current I
Rise Time (Note 1) t
Fall Time (Note 1) t
STANDBY CURRENT
Supply Current I
CM
= 5.1V)
IO
BIAS
IO
VO
(MIN)
(MAX)
TH1
TH2
SOFT
SL
TH(SD)
N(SD)
OL I
OL II
CH I
CH II
UV
LKG
R
F
CC
UC3525A
- -1.510mV
- -110µA
- -0.11µA
≥10MΩ 60 80 - dB
R
L
= 1.5 to 5.2V 60 90 - dB
CM
= 8 to 3.5V 50 60 - dB
CC
- --0%
- 45 49 - %
Zero Duty Cycle 0.7 0.9 - V
Max Duty Cycle - 3.2 3.6 V
VSD = 0V, VSS = 0V 25 51 80 µA
VSD = 25V - 0.3 0.7 V
- 0.6 0.8 1 V
VSD = 2.5V - 0.3 1 mA
I
= 20mA - 0.1 0.4 V
SINK
I
= 100mA - 0.05 2 V
SINK
I
SOURCE
I
SOURCE
= 20mA 18 19 - V
= 100mA 17 18 - V
V8 and V9 = High 678V
VCC = 35V - 80 200 µA
CL = 1uF, TJ = 25°C - 80 600 ns
CL = 1uF, TJ = 25°C - 70 300 ns
VCC = 35V - 12 20 mA
Notes :
1. These parameters. although guaranteed over the recommended operating conditions, are not 100% tested in production
2. Tested at f
=40 KHz (RT =3.6K, CT =0.01uF, R
OSC
= 0Ω)
I
3
Loading...