SG1844 Controller Datasheet

SG1844 Datasheet, PDF, Equivalent


Part Number

SG1844

Description

Current Mode PWM Controller

Manufacture

Microsemi

Total Page 19 Pages
Datasheet
Download SG1844 Datasheet


SG1844
SG1844/SG1845/SG3844/SG3845
Current Mode PWM Controller
Description
The SG1844/45 family of control ICs provides all the
required 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 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 <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 SG3844/45 is designed for the commercial
range of 0°C to 70°C.
Product Highlight
Features
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
Undervoltage Lockout with 6V Hysteresis
(SG1844 only)
Double Pulse Suppression
High-Current Totem-Pole Output
Internally Trimmed Bandgap Reference
500kHz Operation
Under-voltage Lockout
SG1844 - 16 Volts
SG1845 - 8.4 Volts
Low Shoot-through Current <75mA Over
Temperature
Application
Available to MIL-STD-883
Available to DSCC
Standard Microcircuit Drawing (SMD)
SGR1844/45 Rad-Tolerant Version Available
AC
INPUT
RST
IST
Vcc
SG3844
Figure 1 · Product Highlight
November 2014 Rev. 1.7
www.microsemi.com
© 2014 Microsemi Corporation- Analog Mixed Signal Group
1

SG1844
Current Mode PWM Controller
Connection Diagrams and Ordering Information
Ambient
Type
Temperature
Package
Part Number
0°C to 70°C
8-PIN PLASTIC
M DUAL INLINE
PACKAGE
SG3844M
SG3845M
Packaging
Type
PDIP
Connection Diagram
COM
VFB
ISENSE
RT/CT
VREF
VCC
OUTPUT
GND
M PACKAGE
(Top View)
M Package: RoHS / Pb-free 100% Matte Tin Lead Finish
-55°C to
125°C
SG1844Y
SG1845Y
Y
8-PIN
CERAMIC
DUAL INLINE
PACKAGE
SG1844Y-883B
SG1845Y-883B
SG1844Y-DESC
SG1845Y-DESC
8-PIN SMALL
0°C to 70°C
DM
OUTLINE
INTEGRATED
CIRCUIT
SG3844DM
SG3845DM
0°C to 70°C
14-PIN SMALL
D
OUTLINE
INTEGRATED
CIRCUIT
SG3844D
SG3845D
CERDIP
COM
VFB
ISENSE
RT/CT
Y PACKAGE
(Top View)
PbSn Tin Lead Finish
VREF
VCC
OUTPUT
GND
SOIC
SOIC
COM
VFB
ISENSE
VREF
VCC
OUTPUT
RT/CT
GND
DM PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
COM
N.C.
VFB
N.C.
ISENSE
N.C.
RT/CT
VREF
N.C.
VCC
VC
OUT UT
GND
WR GND
D PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
2


Features SG1844/SG1845/SG3844/SG3845 Current Mode PWM Controller Description The SG1844 /45 family of control ICs provides all the required features to implement off- line Fixed Frequency, Current-mode swit ching power supplies with a minimum num ber of external components. Current-mod e architecture demonstrates improved li ne regulation, improved load regulation , pulse-by pulse current limiting and i nherent protection of the power supply output switch. The Bandgap reference is trimmed to ±1% over temperature. Osci llator discharge current is trimmed to less than ±10%. The SG1844/45 has unde r-voltage lockout, current-limiting cir cuitry and start-up current of less tha n 1mA. The totem-pole output is optimiz ed to drive the gate of a power MOSFET. The output is low in the off state to provide direct interface to an Nchannel device. Both operate up to a maximum d uty cycle range of zero to <50% due to an internal toggle flip-flop which blan ks the output off every other clock cycle. The SG1844/45 is speci.
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