Description

The 3842A(AM)/43A(AM)/44A(AM)/45A(AM) 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

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 3842A(AM) and 3844A(AM) have UVLO thresholds of 16 V (on) and 10 V (off). The corresponding

thresholds for the 3843A(AM)/45A(AM) are 8.4V (on) and 7.6V (off). The MIK3842A(AM) and MIK3843A(AM) can operate within 100% duty

cycle. The 3844A(AM) and UC3845A(AM) can operate within 50% duty cycle.

The 384XA(AM) has Start-Up Current 0.17mA (typ).

Features

• Low Start-Up and Operating Current

• High Current Totem Pole Output

• Undervoltage Lockout With Hysteresis

•Operating Frequency Up To 300KHz (384XA)

500KHz

(384XAM

)

Pin Connection

Block diagram

(toggle flip flop used only in MIK3844, MIK3845)

Top view

7

8

V

5V

VREF

SET/

RESET

UVLO

36V

GND

5

2

1

VFB

COMP

INTERNAL

BIAS

1/2 VREF

+

ERR

VRE

GOOD

F

LOGIC

2R

C.S.

COMP

1V

R

R

PWM

LATCH

POWER VCC

7

OUT

6

3

CURRENT

SENSE

R

/C

T

OSCILLATOR

S

T

5

POWER GND

Absolute Maximum Ratings

Symbol

Parameter

Maximum

Units

Supply Voltage (low impedance source)

30

V

Output Current

±1

A

Input Voltage (Analog Inputs pins 2,3)

−0.3 to 5.5

V

Error Amp Output Sink Current

10

mA

Po

1

W

W

Tstg

Storage Temperature Range

-65 to150

Lead Temperature (soldering 5 sec.)

260

1

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