IP1844 데이터 시트보기 (PDF) - Semelab - > TT Electronics plc

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IP1844

CURRENT MODE REGULATING PULSE WIDTH MODULATORS

Semelab - > TT Electronics plc  

SEME

LAB

IP1844 SERIES

IP1845 SERIES

DESCRIPTION

The IP1844 and IP1845 series of switching regulator control circuits contain all the functions necessary to

implement off-line, current mode switching regulators, using a minimum number of external parts.

Functions included are voltage reference, error amplifier, current sense comparator, oscillator, totem-pole output

driver and under-voltage lockout circuitry. In addition there is a toggle flip-flop which blanks the output on every

second clock pulse, thereby ensuring that the duty cycle never exceeds 50%.

Although pin compatible with the UC1844 and UC1845 series, SEMELAB has incorporated several improvements

in the IP1844 and IP1845 series allowing tighter and more complete specification of electrical performance .

BLOCK DIAGRAM

7/12

VCC

GND 5/9

34V

16V

(8.4V)

UNDER–VOLTAGE

LOCKOUT

ENABLE

REFERENCE 5V

REGULATOR

6V

(0.5V) 2.5V

REG

INTERNAL

BIAS

8/14 VREF

R T /CT 4/7

VFB 2/3

COMP 1/1

ISENSE 3/5

OSCILLATOR

ERROR

AMP

2R

R

S

VREF STATUS

LATCH

R

7/11 VC

3.6V

6 /1 0

OUTPUT

Q

T

TOGGLE

FLIP

FLOP

5/8 POW ER

GROUND

S

1V

R

PWM

LATCH

CURRENT

Values in brackets are for IP1845 series.

SENSE

COMPARATOR

PIN NUMBERS

1st Number – N, J and 8 Pin D Packages

2nd Num ber – 14 Pin D Package.

RECOMMENDED OPERATING CONDITIONS

VCC

Supply Voltage

IO

Output Current

Analog Inputs

(pins 2 and 3)

Error Amp Output Sink Current

Operating Ambient Temperature Range

IP1844 , IP1845

IP2844 , IP2845

IP3844 , IP3845

≤ 30V

0 to ±200mA

–0.3V to 3V

0 to 2mA

–55 to 125°C

–25 to 85°C

0 to 70°C

Semelab plc. Telephone (01455) 556565. Telex: 341927. Fax (01455) 552612.

Prelim. 2/95

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