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