UC3842B, UC3843B, UC2842B, UC2843B, NCV3843BV
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4
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
T
A
is the operating ambient temperature range that applies [Note 8], unless otherwise noted.)
UC284XB UC384XB, XBV
Characteristics Symbol Min Typ Max Min Typ Max Unit
OUTPUT SECTION
Output Voltage
Low State (I
Sink
= 20 mA)
(I
Sink
= 200 mA) UC284XB, UC384XB
UC384XBV
High State (I
Source
= 20 mA) UC284XB, UC384XB
UC384XBV
(I
Source
= 200 mA)
V
OL
V
OH
13
12
0.1
1.6
13.5
13.4
0.4
2.2
13
12.9
12
0.1
1.6
1.6
13.5
13.5
13.4
0.4
2.2
2.3
V
Output Voltage with UVLO Activated (V
CC
= 6.0 V, I
Sink
= 1.0 mA) V
OL(UVLO)
0.1 1.1 0.1 1.1 V
Output Voltage Rise Time (C
L
= 1.0 nF, T
J
= 25°C) t
r
50 150 50 150 ns
Output Voltage Fall Time (C
L
= 1.0 nF, T
J
= 25°C) t
f
50 150 50 150 ns
UNDERVOLTAGE LOCKOUT SECTION
Startup Threshold (V
CC
)
UCX842B, BV
UCX843B, BV
V
th
15
7.8
16
8.4
17
9.0
14.5
7.8
16
8.4
17.5
9.0
V
Minimum Operating Voltage After TurnOn (V
CC
)
UCX842B, BV
UCX843B, BV
V
CC(min)
9.0
7.0
10
7.6
11
8.2
8.5
7.0
10
7.6
11.5
8.2
V
PWM SECTION
Duty Cycle
Maximum UC284XB, UC384XB
Maximum UC384XBV
Minimum
DC
(max)
DC
(min)
94
96
0
94
93
96
96
0
%
TOTAL DEVICE
Power Supply Current
Startup (V
CC
= 6.5 V for UCX843B,
Startup V
CC
14 V for UCX842B, BV)
(Note 7)
I
CC
+ I
C
0.3
12
0.5
17
0.3
12
0.5
17
mA
Power Supply Zener Voltage (I
CC
= 25 mA) V
Z
30 36 30 36 V
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
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.
UC3842B, UC3843B, UC2842B, UC2843B, NCV3843BV
http://onsemi.com
5
0.8
2.0
5.0
8.0
20
50
80
R
T
, TIMING RESISTOR (k )
Ω
1.0 M500 k200 k100 k50 k20 k10 k
f
OSC
, OSCILLATOR FREQUENCY (kHz)
V
CC
= 15 V
T
A
= 25°C
Figure 2. Timing Resistor
versus Oscillator Frequency
Figure 3. Output Deadtime
versus Oscillator Frequency
1.0 M500 k200 k100 k50 k20 k10 k
f
OSC
, OSCILLATOR FREQUENCY (kHz)
1.0
2.0
5.0
10
20
50
100
% DT, PERCENT OUTPUT DEADTIME
1
2
Figure 4. Oscillator Discharge Current
versus Temperature
Figure 5. Maximum Output Duty Cycle
versus Timing Resistor
, DISCHARGE CURRENT (mA)
7.0
-55
T
A
, AMBIENT TEMPERATURE (°C)
-25 0 25 50 75 100 125
dischg
I
7.5
8.0
8.5
9.0
V
CC
= 15 V
V
OSC
= 2.0 V
, MAXIMUM OUTPUT DUTY CYCLE (%)
max
D
40
0.8
R
T
, TIMING RESISTOR (kW)
1.0 2.0 3.0 4.0 5.0 6.0 7.0 8.0
50
60
70
80
90
100
I
dischg
= 7.5 mA
V
CC
= 15 V
C
T
= 3.3 nF
T
A
= 25°C
1. C
T
= 10 nF
2. C
T
= 5.0 nF
3. C
T
= 2.0 nF
4. C
T
= 1.0 nF
5. C
T
= 500 pF
6. C
T
= 200 pF
7. C
T
= 100 pF
5
I
dischg
= 8.8 mA
7
3
6
4
V
CC
= 15 V
T
A
= 25°C
Figure 6. Error Amp Small Signal
Transient Response
Figure 7. Error Amp Large Signal
Transient Response
1.0 ms/DIV0.5 ms/DIV
20 mV/DIV
20 mV/DIV
2.55 V
2.50 V
2.45 V
3.0 V
2.5 V
2.0 V
V
CC
= 15 V
A
V
= -1.0
T
A
= 25°C
V
CC
= 15 V
A
V
= -1.0
T
A
= 25°C
Where: Vosc = 1.7 V
I
Rt
= Vref/Rt
Idis = 8.3 mA
Freq +
1
ǒ
Ct
Vosc
I
Rt
Ǔ
)
ǒ
Ct
Vosc
Idis*I
Rt
Ǔ
UC3842B, UC3843B, UC2842B, UC2843B, NCV3843BV
http://onsemi.com
6

UC3842BD1

Mfr. #:
Manufacturer:
STMicroelectronics
Description:
Switching Controllers 0.5mA Current Mode
Lifecycle:
New from this manufacturer.
Delivery:
DHL FedEx Ups TNT EMS
Payment:
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