UC3842B Datasheet PDF - ON Semiconductor
| Part Number | UC3842B | |
| Description | (UC3842B / UC3843B) HIGH PERFORMANCE CURRENT MODE CONTROLLERS | |
| Manufacturers | ON Semiconductor | |
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UC3842B, UC3843B,
UC2842B, UC2843B
High Performance
Current Mode Controllers
The UC3842B, UC3843B series are high performance fixed
frequency current mode controllers. They are specifically designed for
Off−Line and DC−DC converter applications offering the designer a
cost−effective solution with minimal external components. These
integrated circuits feature a trimmed oscillator for precise duty cycle
control, a temperature compensated reference, high gain error
amplifier, current sensing comparator, and a high current totem pole
output ideally suited for driving a power MOSFET.
Also included are protective features consisting of input and
reference undervoltage lockouts each with hysteresis, cycle−by−cycle
current limiting, programmable output deadtime, and a latch for single
pulse metering.
These devices are available in an 8−pin dual−in−line and surface
mount (SOIC−8) plastic package as well as the 14−pin plastic surface
mount (SOIC−14). The SOIC−14 package has separate power and
ground pins for the totem pole output stage.
The UCX842B has UVLO thresholds of 16 V (on) and 10 V (off),
ideally suited for off−line converters. The UCX843B is tailored for
lower voltage applications having UVLO thresholds of 8.5 V (on) and
7.6 V (off).
Features
• Trimmed Oscillator for Precise Frequency Control
• Oscillator Frequency Guaranteed at 250 kHz
• Current Mode Operation to 500 kHz
• Automatic Feed Forward Compensation
• Latching PWM for Cycle−By−Cycle Current Limiting
• Internally Trimmed Reference with Undervoltage Lockout
• High Current Totem Pole Output
• Undervoltage Lockout with Hysteresis
• Low Startup and Operating Current
• This is a Pb−Free and Halide−Free Device
VCC 7(12)
Vref
8(14)
R
5.0V
Reference
VCC
Undervoltage
Lockout
Vref
R Undervoltage
Lockout
VC
7(11)
RT/CT
Oscillator
Output
4(7)
Voltage
Feedback
+
Latching
PWM
6(10)
Power
Ground
Input -
5(8)
2(3)
Output
Compensation
1(1)
Error
Amplifier
GND 5(9)
Current
Sense
3(5) Input
Pin numbers in parenthesis are for the D suffix SOIC−14 package.
Figure 1. Simplified Block Diagram
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8
1
14
1
8
1
PDIP−8
N SUFFIX
CASE 626
SOIC−14
D SUFFIX
CASE 751A
SOIC−8
D1 SUFFIX
CASE 751
PIN CONNECTIONS
Compensation 1
Voltage Feedback 2
Current Sense 3
RT/CT 4
8 Vref
7 VCC
6 Output
5 GND
(Top View)
Compensation 1
NC 2
Voltage Feedback 3
NC 4
Current Sense 5
NC 6
RT/CT 7
14 Vref
13 NC
12 VCC
11 VC
10 Output
9 GND
8 Power Ground
(Top View)
ORDERING INFORMATION
See detailed ordering and shipping information in the package
dimensions section on page 17 of this data sheet.
DEVICE MARKING INFORMATION
See general marking information in the device marking
section on page 19 of this data sheet.
© Semiconductor Components Industries, LLC, 2013
September, 2013 − Rev. 17
1
Publication Order Number:
UC3842B/D
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UC3842B, UC3843B, UC2842B, UC2843B
80
50
20
8.0
5.0
2.0 VCC = 15 V
TA = 25°C
0.8
10 k
20 k
50 k 100 k 200 k
500 k
fOSC, OSCILLATOR FREQUENCY (kHz)
1.0 M
Figure 2. Timing Resistor
versus Oscillator Frequency
100
1. CT = 10 nF
50 2. CT = 5.0 nF
3. CT = 2.0 nF
4. CT = 1.0 nF
20 5. CT = 500 pF
6. CT = 200 pF
10 7. CT = 100 pF
5.0
4
3
2
1
7
6
5
2.0
1.0
10 k
VCC = 15 V
TA = 25°C
20 k
50 k 100 k 200 k
500 k
fOSC, OSCILLATOR FREQUENCY (kHz)
1.0 M
Figure 3. Output Deadtime
versus Oscillator Frequency
9.0
VCC = 15 V
VOSC = 2.0 V
8.5
8.0
7.5
7.0
- 55
- 25 0
25 50 75 100
TA, AMBIENT TEMPERATURE (°C)
Figure 4. Oscillator Discharge Current
versus Temperature
125
100
90
80
70 Idischg = 8.54 mA
60
VCC = 15 V
CT = 3.3 nF
50 TA = 25°C
40
0.8 1.0
2.0 3.0 4.0 5.0 6.0 7.0 8.0
RT, TIMING RESISTOR (kW)
Figure 5. Maximum Output Duty Cycle
versus Timing Resistor
2.55 V
2.50 V
VCC = 15 V
AV = -1.0
TA = 25°C
2.45 V
0.5 ms/DIV
Figure 6. Error Amp Small Signal
Transient Response
3.0 V
2.5 V
VCC = 15 V
AV = -1.0
TA = 25°C
2.0 V
1.0 ms/DIV
Figure 7. Error Amp Large Signal
Transient Response
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Part DetailsOn this page, you can learn information such as the schematic, equivalent, pinout, replacement, circuit, and manual for UC3842B electronic component. |
| Information | Total 22 Pages | |
| Link URL | [ Copy URL to Clipboard ] | |
| Download | [ UC3842B.PDF Datasheet ] | |
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