O F

1

Copyright

© 2000

Rev. 1.6c,2006-02-02

SG1844/SG1845 Series

DESCRIPTION

The

SG1844/45

family

of

control

ICs

provides

all

the

necessary

features

to

implement off-line fixed frequency, current-

mode switching power supplies with a

minimum number of external components.

Current-mode

architecture

demonstrates

improved line regulation, improved load

regulation, pulse-by pulse current limiting

and inherent protection of the power supply

output switch.

The bandgap reference is

trimmed to ±1% over temperature. Oscillator

discharge current is trimmed to less than

±10%. The SG1844/45 has undervoltage

lockout, current-limiting circuitry

and start-up current of less than 1mA. The

totem-pole output is optimized to drive the

gate of a power MOSFET. The output is low

in the off state to provide direct interface to

an N-channel device. Both operate up to a

maximum duty cycle range of zero to <50%

due to an internal toggle flip-flop which

blanks the output off every other clock

cycle. The SG1844/45 is specified for

operation over the full military ambient

temperature range of -55°C to 125°C. The

SG2844/45 is specified for the industrial

range of -25°C to 85°C, and the SG3844/45

is designed for the commercial range of 0°C

to 70°C.

IMPORTANT: For the most current data, consult MICROSEMI’s website: http://www.microsemi.com

PRODUCT H I GHLIGHT

AC

INPUT

SG3844

R

ST

I

ST

V

CC

K EY FE AT UR ES

OPTIMIZED FOR OFF-LINE

CONTROL

LOW START-UP CURRENT

(<1mA)

AUTOMATIC FEED FORWARD

COMPENSATION

TRIMMED OSCILLATOR

DISCHARGE CURRENT

PULSE-BY-PULSE CURRENT

LIMITING

ENHANCED LOAD RESPONSE

CHARACTERISTICS

UNDER-VOLTAGE LOCKOUT

WITH 6V HYSTERESIS

(SG1844 only)

DOUBLE PULSE

SUPPRESSION

HIGH-CURRENT TOTEM-POLE

OUTPUT

INTERNALLY TRIMMED

BANDGAP REFERENCE

500kHz OPERATION

UNDERVOLTAGE LOCKOUT

SG1844 - 16 volts SG1845 - 8.4

volts

LOW SHOOT-THROUGH

CURRENT <75mA OVER

TEMPERATURE

HIGH RELI A B I LI TY

FE AT URES

AVAILABLE TO MIL-STD-883B

LINFINITY LEVEL "S"

PROCESSING AVAILABLE

PACKAGE ORDER INFO

M

Plastic DIP

8-Pin

N

Plastic DIP

14-Pin

DM

Plastic SOIC

8-Pin

D

Plastic SOIC

14-Pin

Y

Ceramic Dip

8-Pin

J

Ceramic DIP

14-Pin

F

Cer Flatpack

10-Pin

L

Ceramic LCC

20-Pin

RoHS Compliant / Pb-free

Transition DC: 0503

RoHS Compliant / Pb-free

Transition DC:0440

SG3844M

SG3844N

SG3844DM

SG3844D

SG3844Y

SG3844J

0 to 70

SG3845M

SG3845N

SG3845DM

SG3845D

SG3845Y

SG3845J

SG2844M

SG28424N

SG2844DM

SG2842D

SG2844Y

SG2844J

-25 to 85

SG2845M

SG2845N

SG2845DM

SG2845D

SG2845Y

SG2845J

SG1844Y

SG1844J

SG1844L

-55 to

125

SG1845Y

SG1845J

SG1845L

SG1842Y/883B

SG1844J/883B

SG1844L/883B

MIL-

STD/883

SG1845Y/883B

SG1845J/883

SG1845L/883B

DESC

SG1844Y/DESC

SG1844J/DESC

SG1844F/DESC SG1844L/DESC

Note: Available in Tape & Reel. Append the letters “TR” to the part number. (i.e. LXSG3844N-TR)