UC3842B, UC3843B, UC2842B, UC2843B
ELECTRICAL CHARACTERISTICS
(V
CC
= 15 V [Note 7], R
T
= 10 k, C
T
= 3.3 nF. For typical values T
A
= 25°C, for min/max values
UC284XB, UC2843D
Characteristics
CURRENT SENSE SECTION
Current Sense Input Voltage Gain (Notes 5 and 6)
UC2843D, UC284XB, UC384XB
UC384XBV
Maximum Current Sense Input Threshold (Note 5)
UC2843D, UC284XB, UC384XB
UC384XBV
Power Supply Rejection Ratio (V
CC
= 12 V to 25 V, Note 5)
Input Bias Current
Propagation Delay (Current Sense Input to Output)
OUTPUT SECTION
Output Voltage
Low State (I
Sink
= 20 mA)
(I
Sink
= 200 mA)
High State
(I
Source
= 20 mA)
(I
Source
= 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 (V
CC
)
UCX842B, BV
UCX843B, BV, D
UCX842B, BV
UCX843B, BV, D
V
th
15
7.8
9.0
7.0
16
8.4
10
7.6
17
9.0
11
8.2
14.5
7.8
8.5
7.0
16
8.4
10
7.6
17.5
9.0
11.5
8.2
V
V
OL(UVLO)
t
r
t
f
V
OL
V
OH
−
−
−
13
−
12
−
−
−
0.1
1.6
−
13.5
−
13.4
0.1
50
50
0.4
2.2
−
−
−
−
1.1
150
150
−
−
−
13
12.9
12
−
−
−
0.1
1.6
1.6
13.5
13.5
13.4
0.1
50
50
0.4
2.2
2.3
−
−
−
1.1
150
150
V
A
V
2.85
−
0.9
−
−
−
−
3.0
−
1.0
−
70
−
2.0
150
3.15
−
1.1
−
−
−10
300
2.85
2.85
0.9
0.85
−
−
−
3.0
3.0
1.0
1.0
70
−
2.0
150
3.15
3.25
1.1
1.1
−
−10
300
V/V
Symbol
Min
Typ
Max
UC384XB, XBV
Min
Typ
Max
Unit
T
A
is the operating ambient temperature range that applies [Note 8], unless otherwise noted.)
V
th
V
PSRR
I
IB
t
PLH(In/Out)
dB
mA
ns
UC284XB, UC384XB
UC384XBV, UC2843D
UC284XB, UC384XB
UC384XBV, UC2843D
V
ns
ns
Minimum Operating Voltage After Turn−On (V
CC
)
V
CC(min)
V
PWM SECTION
Duty Cycle
Maximum UC284XB, UC384XB, UC2843D
Maximum
UC384XBV
Minimum
TOTAL DEVICE
Power Supply Current
Startup (V
CC
= 6.5 V for UCX843B, UC2843D
Startup
V
CC
14 V for UCX842B, BV)
(Note 7)
Power Supply Zener Voltage (I
CC
= 25 mA)
5. This parameter is measured at the latch trip point with V
FB
= 0 V.
6. Comparator gain is defined as: A
V
DV
Output Compensation
7. Adjust V
CC
above the Startup threshold before setting to 15 V.
8. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible.
T
low
= 0°C for UC3842B, UC3843B;
−25°C
for UC2842B, UC2843B;
−40°C
for UC3842BV, UC3843BV, UC2843D
T
high
= +70°C for UC3842B, UC3843B; +85°C for UC2842B, UC2843B, UC2843D; +105°C for UC3842BV, UC3843BV
DV
Current Sense Input
DC
(max)
DC
(min)
94
−
−
96
−
−
−
−
0
94
93
−
96
96
−
−
−
0
%
I
CC
+ I
C
−
−
0.3
12
36
0.5
17
−
−
−
30
0.3
12
36
0.5
17
−
mA
V
Z
30
V
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