SLUS191C – FEBRUARY 1997 – REVISED JANUARY 2008
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These devices have limited built-in ESD protection. The leads should be shorted together or the device placed in conductive foam
during storage or handling to prevent electrostatic damage to the MOS gates.
DESCRIPTION (continued)
These functions are also controlled by an undervoltage lockout which keeps the outputs off and the soft-start
capacitor discharged for sub-normal input voltages. This lockout circuitry includes approximately 500 mV of
hysteresis for jitter- free operation. Another feature of these PWM circuits is a latch following the comparator.
Once a PWM pulse has been terminated for any reason, the outputs will remain off for the duration of the period.
The latch is reset with each clock pulse. The output stages are totem-pole designs capable of sourcing or sinking
in excess of 200 mA. The UC1525A output stage features NOR logic, giving a LOW output for an OFF state. The
UC1527A utilizes OR logic which results in a HIGH output level when OFF.
ABSOLUTE MAXIMUM RATINGS
(1)
UCx52xA
+V
IN
V
C
Supply voltage
Collector supply voltage
Logic inputs
Analog inputs
Output current, source or sink
Reference output current
Oscillator charging current
Power dissipation at T
A
= +25°C
Operating junction temperature
Storage temperature range
Lead temperature (soldering, 10 seconds)
(1)
(2)
Values beyond which damage may occur.
See Thermal Characteristics table.
(2)
UNIT
40
40
–0.3 to +5.5
–0.3 to +V
IN
500
50
5
1000
2000
–55 to 150
–65 to 150
300
°C
mW
mA
V
Power dissipation at T
C
= +25°C
(2)
RECOMMENDED OPERATING CONDITIONS
(1)
MIN
+V
IN
V
C
Input voltage
Collector supply voltage
Sink/source load current (steady state)
Sink/source load current (peak)
Reference load current
Oscillator frequency range
Oscillator timing resistor
Oscillator timing capacitorm
Dead time resistor range
UC1525A, UC1527A
Operating ambient temperature range
UC2525A, UC2527A
UC3525A, UC3527A
(1)
Range over which the device is functional and parameter limits are assured.
8
4.5
0
0
0
100
2
0.001
0
–55
–25
0
MAX
35
35
100
400
20
400
150
0.01
500
125
85
70
°C
Hz
kΩ
µF
Ω
mA
UNIT
V
2
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