UC3842A-BW Просмотр технического описания (PDF) - First Components International

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UC3842A-BW

Current Mode PWM Controller

First Components International 

UC384XA-BW Current Mode PWM Controller

(UC3842A-BW/ 43A-BW/ 44A-BW/ 45A-BW)

DESCRIPTION

The UC3842A-BW/43A-BW/44A-BW/45A-BW are fixed frequency current mode PWM

controller. They are specially designed for OFF−Line and DC to DC converter applications

with a minimal external components. Internally implemented circuits include a trimmed

PIN

CONNECTION

(TOP VIEW)

oscillator for precise duty cycle control, a temperature compensated reference, high gain

error amplifier, current sensing comparator, and a high current totempole output ideally

suited for driving a power MOSFET. Protection circuitry includes built undervoltage lockout

and current limiting.

The UC3842A-BW and UC3844A-BW have UVLO thresholds of 16 V (on) and 10 V (off). The

corresponding thresholds for the UC3843A-BW/45A-BW are 8.4V (on) and

7.6V (off).

The UC3842A-BW and UC3843A-BW can operate within 100% duty cycle. The UC3844A-BW

and UC3845A-BW can operate within 50% duty cycle.

The UC384XA-BW has Start-Up Current 0.17mA (typ).

The UC384XA-BW are revised UC384XAM and differ by higher Unity Gain bandwidth of Error Amplifier.

FEATURES

• Low Start-Up and Operating Current

• High Current Totem Pole Output

• Undervoltage Lockout With Hysteresis

• Operating Frequency Up To 500KHz

BLOCK DIAGRAM

(toggle flip flop used only in UC3844, UC3845)

Absolute Maximum Ratings

Characteristic

Supply Voltage (low impedance

source)

Output Current

Input Voltage (Analog Inputs pins 2,3)

Error Amp Output Sink Current

Power Dissipation (TA=250C)

Storage Temperature Range

Lead Temperature (soldering 5 sec.)

Symbol

VCC

IO

VI

ISINK (E.A)

PO

Tstg

TL

Value

30

±1

−0.3 to 5.5

10

1

-65 to150

260

Unit

V

A

V

mA

W

oC

oC

1

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