UC3843BD ON Semiconductor, UC3843BD Datasheet - Page 11

• Manufacturer Part Number: UC3843BD
• Description: IC CTRLR CURRENT MODE HP 14SOIC
• Manufacturer: ON Semiconductor

Specifications of UC3843BD

• Pwm Type: Current Mode
• Number Of Outputs: 1
• Frequency - Max: 275kHz
• Duty Cycle: 96%
• Voltage - Supply: 8.2 V ~ 25 V
• Buck: No
• Boost: Yes
• Flyback: Yes
• Inverting: No
• Doubler: No
• Divider: No
• Cuk: No
• Isolated: Yes
• Operating Temperature: 0°C ~ 70°C
• Package / Case: 14-SOIC (3.9mm Width), 14-SOL
• Frequency-max: 275kHz
• Duty Cycle (max): 96 %
• Output Voltage: 4.9 V to 5.1 V
• Output Current: 1000 mA
• Mounting Style: SMD/SMT
• Switching Frequency: 500 KHz
• Operating Supply Voltage: 30 V
• Maximum Operating Temperature: + 70 C
• Fall Time: 50 ns
• Minimum Operating Temperature: 0 C
• Rise Time: 50 ns
• Synchronous Pin: No
• Topology: Boost, Flyback, Forward
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: UC3843BDOS

DI
Inductor
Current
Control Voltage
f +
C
Control Voltage
R
R
6
5
2
A
B
(R A ) 2R B )C
8
1.44
Figure 20. Continuous Current Waveforms
Figure 22. External Duty Cycle Clamp and
1
5.0k
5.0k
5.0k
t
t
4
0
m
MC1455
Multi−Unit Synchronization
1
R
S
Oscillator Period
Dl ) Dl m 2
D (max) +
Q
4
DI
m
Oscillator Period
1
m 1
R A ) 2R B
m
t
3
7
2
1
R B
m
3
(B)
(A)
8(14)
4(7)
2(3)
1(1)
t
Dl ) Dl m 2
2
t
m
5
To Additional
UCX84XBs
2
EA
m 1
R
R
m 2
m 1
+
Osc
Bias
http://onsemi.com
2R
Inductor
Current
R
t
3
t
6
5(9)
11
R
R
2
1
V
8(14)
Clamp
4(7)
2(3)
1(1)
Figure 23. Adjustable Reduction of Clamp Level
External
≈
The diode clamp is required if the Sync amplitude is large enough to cause the bottom
side of C
Sync
Input
R 2
R 1
R
R
Figure 21. External Clock Synchronization
EA
T
1.67
) 1
to go more than 300 mV below ground.
+
Osc
Bias
1.0 mA
0.01
+ 0.33x10
2R
R
C
-
+
-3
R
47
T
V
5(9)
T
Clamp
1.0V
R 1 ) R 2
R 1 R 2
5.0V Ref
8(14)
V
4(7)
2(3)
1(1)
ref
Comp/Latch
S
R
Where: 0 ≤ V
I pk(max) [
Q
EA
R
R
Clamp
+
V Clamp
Osc
7(12)
R S
+
-
Bias
≤ 1.0 V
V
CC
7(11)
6(10)
5(8)
3(5)
2R
R
5(9)
V
Q1
R
in
S