LIN DOC #: 1844
SG1844/SG1845 Series
U R R E N T M O D E P W M C O N T R O L L E R
C
T H E I N F I N I T E P O W E R O F I N N O V A T I O N
P R O D U C T I O N D A T A S H E E T
DESCRIPTION
KEY FEATURES
■ OPTIMIZED FOR OFF-LINE CONTROL
■ LOW START-UP CURRENT (<1mA)
■ AUTOMATIC FEED FORWARD
COMPENSATION
■ TRIMMED OSCILLATOR DISCHARGE
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
1ꢀ over temperature. Oscillator
discharge current is trimmed to less than
1ꢁꢀ. The SG1844/45 has under-
voltage 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 <5ꢁꢀ 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 ꢁ°C to 7ꢁ°C.
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
PRODUCT HIGHLIGHT
■ LOW SHOOT-THROUGH CURRENT <75mA
OVER TEMPERATURE
TYPICAL APPLICATION OF SG3844 IN A FLYBACK CONVERTER
HIGH RELIABILITY FEATURES
RST
■ AVAILABLE TO MIL-STD-883B
■
LINFINITY LEVEL "S" PROCESSING AVAILABLE
IST
AC
INPUT
VCC
SG3844
PACKAGE ORDER INFORMATION
Plastic DIP
8-pin
Plastic DIP
14-pin
Plastic SOIC
8-pin
Plastic SOIC
14-pin
Ceramic DIP
8-pin
Ceramic DIP
14-pin
Cer. Flatpack Ceramic LCC
L
1ꢁ-pin 2ꢁ-pin
TA (°C)
0 to 70
M
N
DM
D
Y
J
F
SG3844M
SG3844N
SG3844DM
SG3844D
SG3844Y
SG3845Y
SG2844Y
SG2845Y
SG1844Y
SG1845Y
SG3844J
SG3845J
SG2844J
SG2845J
SG1844J
SG1845J
—
—
—
—
—
—
—
—
—
—
SG3845M
SG3845N
SG3845DM
SG3845D
SG2844M
SG2844N
SG2844DM
SG2844D
—
-25 to 85
-55 to 125
MIL-STD/883
DESC
SG2845M
SG2845N
SG2845DM
SG2845D
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
—
SG1844L
SG1845L
SG1844Y/883B SG1844J/883B
SG1845Y/883B SG1845J/883B
SG1844L/883B
SG1845L/883B
SG1844Y/DESC SG1844J/DESC SG1844F/DESC SG1844L/DESC
SG1845Y/DESC SG1845J/DESC SG1845F/DESC SG1845L/DESC
Note: All surface-mount packages are available in Tape & Reel.
F O R F U R T H E R I N F O R M AT I O N C A L L ( 7 1 4 ) 8 9 8 - 8 1 2 1
Copyright © 2000
Rev. 1.4 4/00
11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841
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