UC3842ADX

UC3842ADX Datasheet

UC3842A/UC3843A

Part	Datasheet
UC3842ADX	UC3842ADX (pdf)

Related Parts	Information
UC3843ADX	UC3843ADX
UC3843AD	UC3843AD
UC3842AN	UC3842AN
UC3842AD	UC3842AD

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UC3842A/UC3843A SMPS Controller • Low Start Current 0.2mA typ • Operating Range Up To 500KHz • Cycle by Cycle Current Limiting • Under Voltage Lock Out With Hysteresis • Short Shutdown Delay Time typ.100ns • High Current Totem-pole Output • Output Swing Limiting 22V The UC3842A/UC3843A are fixed PWM controller for OffLine and DC to DC converter applications. The internal circuits include UVLO, low start up current circuit, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem-pole output for driving a POWER MOSFET. Also UC3842A/ UC3843A provide low start up current below 0.3mA and short shutdown delay time typ. 100ns. The UC3842A has UVLO threshold of 16V on and 10V off . The UC3843A is 8.4V on and 7.6V off . The UC3842A and UC3843A can operate within 100% duty cycle. 8-DIP Internal Block Diagram 1 8-SOP VREF 8 Internal Bias 5V VREF SET/ RESET Good LOGIC UVLO VFB 2 COMP 1 1/2VREF Error Amp + - 1/3 1V C.S PWM Comp. LATCH C.S 3 RT/CT 4 OSCILLATOR 7 VCC 29V 5 GND PWR VC 22V 6 OUTPUT PWR GND 2000 Fairchild Semiconductor International UC3842A/UC3843A Absolute Maximum Ratings Parameter Value Unit Supply Voltage Output Current Analog Inputs pin 2, 3 VI ANA Error Amp. Output Sink Current ISINK EA Power Dissipation Electrical Characteristics VCC = 15V, RT = CT = 3.3nF, TA = 0°C to + 70°C ,Unless otherwise specified Ordering Information Product Number UC3842AN UC3842AD UC3843AN UC3843AD Package 8 DIP 8 SOP 8 DIP 8 SOP Operating Temperature 0 ~ + 70°C UC3842A/UC3843A UC3842A/UC3843A LIFE SUPPORT POLICY FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR INTERNATIONAL. As used herein: Life support devices or systems are devices or systems which, a are intended for surgical implant into the body, or b support or sustain life, and c whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness. 7/12/00 0.0m 001 ” 2000 Fairchild Semiconductor International

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UC3842A/UC3843A

SMPS Controller
• Low Start Current 0.2mA typ
• Operating Range Up To 500KHz
• Cycle by Cycle Current Limiting
• Under Voltage Lock Out With Hysteresis
• Short Shutdown Delay Time typ.100ns
• High Current Totem-pole Output
• Output Swing Limiting 22V

The UC3842A/UC3843A are fixed PWM controller for OffLine and DC to DC converter applications. The internal circuits include UVLO, low start up current circuit, temperature compensated reference, high gain error amplifier, current sensing comparator, and high current totem-pole output for driving a POWER MOSFET. Also UC3842A/ UC3843A provide low start up current below 0.3mA and short shutdown delay time typ. 100ns. The UC3842A has UVLO threshold of 16V on and 10V off . The UC3843A is 8.4V on and 7.6V off . The UC3842A and UC3843A can operate within 100% duty cycle.
8-DIP

Internal Block Diagram
1 8-SOP

VREF 8

Internal Bias
5V VREF

SET/ RESET

Good LOGIC

UVLO

VFB 2 COMP 1
1/2VREF

Error Amp + -
1/3 1V

C.S PWM Comp. LATCH

C.S 3

RT/CT 4

OSCILLATOR
7 VCC 29V
5 GND

PWR VC
22V 6 OUTPUT

PWR GND
2000 Fairchild Semiconductor International

UC3842A/UC3843A

Absolute Maximum Ratings

Parameter

Value

Unit

Supply Voltage

Output Current

Analog Inputs pin 2, 3

VI ANA

Error Amp. Output Sink Current

ISINK EA

Power Dissipation

Electrical Characteristics

VCC = 15V, RT = CT = 3.3nF, TA = 0°C to + 70°C ,Unless otherwise specified
Ordering Information

Product Number UC3842AN UC3842AD UC3843AN UC3843AD

Package 8 DIP 8 SOP 8 DIP 8 SOP

Operating Temperature 0 ~ + 70°C

UC3842A/UC3843A

UC3842A/UC3843A

LIFE SUPPORT POLICY

FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR INTERNATIONAL. As used herein:

Life support devices or systems are devices or systems which, a are intended for surgical implant into the body, or b support or sustain life, and c whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user.

A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.
7/12/00 0.0m 001 ” 2000 Fairchild Semiconductor International

Notice: we do not provide any warranties that information, datasheets, application notes, circuit diagrams, or software stored on this website are up-to-date or error free. The archived UC3842ADX Datasheet file may be downloaded here without warranties.

Datasheet ID: UC3842ADX 634812