UC3844A Просмотр технического описания (PDF) - First Components International

Номер в каталоге

Компоненты Описание

производитель

UC3844A

High Performance Current Mode Controller

First Components International 

UC3844A High Performance

Current Mode Controller

The UC3844A series of high performance

fixed frequency current mode controllers are

specifically designed for off–line and dc–to–dc

converter applications offering the designer a cost

effective solution with minimal external components.

This integrated circuit features an oscillator, 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,

a latch for single pulse metering, and a flip-flop which

blanks the output off every other oscillator cycle,

allowing output deadtimes to be programmed for 50%

to 70%.

This device is available in an 8–pin dual–in–

line plastic package as well as the 14–pin plastic sur-

face mount (SOP–14). The SOP–14 package has sepa-

rate power and ground pins for the totem pole output

stage.

The UC3844A has UVLO thresholds of

16V (on) and 10V (off), Ideally suited for off-line

converters.

l Output Deadtime Adjustable from 50% to 70%

l Current Mode Operation to 500 kHz

l Automatic Feed Forward Compensation

l Latching PWM for Cycle–By–Cycle Current Limiting

l Internally Trimmed Reference with Undervoltage Lockout

l High Current Totem Pole Output

l Undervoltage Lockout with Hysteresis

l Low Startup and Operating Current

CD SUFFIX

PLASTIC PACKAGE

8 DIP

D8 SUFFIX

PLASTIC PACKAGE

8 SOP

CS SUFFIX

PLASTIC PACKAGE

SOP-14

SIMPLIFIED BLOCK DIAGRAM

PIN CONNECTIONS

Pin numbers adjacent to terminals are for the D suffix 8-DIP package.

Pin numbers in parenthesis are for the S suffix SOP–14 package.

NOTES:

1. Maximum Package power dissipation limits must be observed.

2. Adjust VCC above the Startup threshold before setting to 15 V.

3. Low duty cycle pulse techniques are used during test to maintain junction temperature as close to ambient as possible

Tlow = 0°C, Thigh = +70°C.

4. This parameter is measured at the latch trip point with VFB = 0V.

5. Comparator gain is defined as: AV

∆V Output Compensation

∆V Current Sense Input

4-24

Share Link: