UC3842B, UC3843B, UC2842B, UC2843B, NCV3843BV
ELECTRICAL CHARACTERISTICS
(V
CC
= 15 V [Note 8], R
T
= 10 k, C
T
= 3.3 nF, for typical values T
A
= 25°C, for min/max values
T
A
is the operating ambient temperature range that applies [Note 9], unless otherwise noted.)
UC284XB
Characteristics
PWM SECTION
Duty Cycle
Maximum (UC284XB, UC384XB)
Maximum
(UC384XBV)
Minimum
TOTAL DEVICE
Power Supply Current
Startup (V
CC
= 6.5 V for UCX843B,
Startup
(V
CC
14 V for UCX842B, BV)
Operating (Note 8)
Power Supply Zener Voltage (I
CC
= 25 mA)
I
CC
+ I
C
–
–
V
Z
30
0.3
12
36
0.5
17
–
–
–
30
0.3
12
36
0.5
17
–
V
mA
%
DC
(max)
DC
(min)
94
–
–
96
–
–
–
–
0
94
93
–
96
96
–
–
–
0
Symbol
Min
Typ
Max
Min
UC384XB, BV
Typ
Max
Unit
8. Adjust V
CC
above the Startup threshold before setting to 15 V.
9. 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
T
high
= +70°C for UC3842B, UC3843B; +85°C for UC2842B, UC2843B; +105°C for UC3842BV, UC3843BV
NCV3843BV: T
low
= –40°C, T
high
= +125°C. Guaranteed by design. NCV prefix is for automotive and other applications requiring site and
change control.
80
% DT, PERCENT OUTPUT DEADTIME
50
R T, TIMING RESISTOR (k
Ω
)
20
8.0
5.0
2.0
0.8
10 k
V
CC
= 15 V
T
A
= 25°C
20 k
50 k
100 k
200 k
500 k
f
OSC
, OSCILLATOR FREQUENCY (kHz)
1.0 M
100
1. C
T
= 10 nF
50 2. C
T
= 5.0 nF
3. C
T
= 2.0 nF
4. C
T
= 1.0 nF
20 5. C
T
= 500 pF
6. C
T
= 200 pF
10 7. C
T
= 100 pF
4
2
1
5
6
7
3
5.0
2.0
1.0
10 k
20 k
V
CC
= 15 V
T
A
= 25°C
50 k
100 k
200 k
500 k
f
OSC
, OSCILLATOR FREQUENCY (kHz)
1.0 M
Figure 2. Timing Resistor
versus Oscillator Frequency
9.0
I dischg , DISCHARGE CURRENT (mA)
V
CC
= 15 V
V
OSC
= 2.0 V
8.5
100
90
80
70
60
50
40
0.8
1.0
Figure 3. Output Deadtime
versus Oscillator Frequency
D max , MAXIMUM OUTPUT DUTY CYCLE (%)
I
dischg
= 7.5 mA
8.0
7.5
I
dischg
= 8.8 mA
V
CC
= 15 V
C
T
= 3.3 nF
T
A
= 25°C
5.0 6.0 7.0 8.0
7.0
- 55
- 25
0
25
50
75
T
A
, AMBIENT TEMPERATURE (°C)
100
125
2.0
3.0
4.0
R
T
, TIMING RESISTOR (kΩ)
Figure 4. Oscillator Discharge Current
versus Temperature
Figure 5. Maximum Output Duty Cycle
versus Timing Resistor
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