UC3842A, UC3843A, UC2842A, UC2843A
ELECTRICAL CHARACTERISTICS
(V
CC
= 15 V, [Note 4], R
T
= 10 k, C
T
= 3.3 nF, T
A
= T
low
to T
high
[Note 5],
unless otherwise noted.)
UC284XA
Characteristics
CURRENT SENSE SECTION
Current Sense Input Voltage Gain (Notes 6 & 7)
Maximum Current Sense Input Threshold (Note 6)
Power Supply Rejection Ratio
V
CC
= 12 to 25 V (Note 6)
Input Bias Current
Propagation Delay (Current Sense Input to Output)
OUTPUT SECTION
Output Voltage
Low State (I
Sink
= 20 mA)
Low State
(I
Sink
= 200 mA)
High State (I
Sink
= 20 mA)
High State
(I
Sink
= 200 mA)
Output Voltage with UVLO Activated
V
CC
= 6.0 V, I
Sink
= 1.0 mA
Output Voltage Rise Time (C
L
= 1.0 nF, T
J
= 25°C)
Output Voltage Fall Time (C
L
= 1.0 nF, T
J
= 25°C)
UNDERVOLTAGE LOCKOUT SECTION
Startup Threshold
UCX842A
UCX843A
Minimum Operating Voltage After Turn−On
UCX842A
UCX843A
PWM SECTION
Duty Cycle
Maximum
Minimum
TOTAL DEVICE
Power Supply Current (Note 4)
Startup:
(V
CC
= 6.5 V for UCX843A,
(V
CC
=
14 V for UCX842A) Operating
Power Supply Zener Voltage (I
CC
= 25 mA)
I
CC
−
−
V
Z
30
0.5
12
36
1.0
17
−
−
−
30
0.5
12
36
1.0
17
−
V
mA
%
DC
max
DC
min
94
−
96
−
−
0
94
−
96
−
−
0
V
th
15
7.8
V
CC(min)
9.0
7.0
10
7.6
11
8.2
8.5
7.0
10
7.6
11.5
8.2
16
8.4
17
9.0
14.5
7.8
16
8.4
17.5
9.0
V
V
V
V
OL
V
OH
V
OL(UVLO)
−
t
r
t
f
−
−
0.1
50
50
1.1
150
150
−
−
−
0.1
50
50
1.1
150
150
ns
ns
−
−
13
12
0.1
1.6
13.5
13.4
0.4
2.2
−
−
−
−
13
12
0.1
1.6
13.5
13.4
0.4
2.2
−
−
V
A
V
V
th
PSRR
−
I
IB
t
PLH(in/out)
−
−
70
−2.0
150
−
−10
300
−
−
−
70
−2.0
150
−
−10
300
mA
ns
2.85
0.9
3.0
1.0
3.15
1.1
2.85
0.9
3.0
1.0
3.15
1.1
V/V
V
dB
Symbol
Min
Typ
Max
Min
UC384XA
Typ
Max
Unit
4. Adjust V
CC
above the Startup threshold before setting to 15 V.
5. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
T
low
= 0°C for UC3842A, UC3843A
T
high
= +70°C for UC3842A, UC3843A
−25°C for UC2842A, UC2843A
+85°C for UC2842A, UC2843A
6. This parameter is measured at the latch trip point with V
FB
= 0 V.
DV
Output Compensation
7. Comparator gain is defined as: A
V
DV
Current Sense Input
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