SG1842/SG1843
Current Mode PWM Controller
Description
The SG1842/43 family of control IC's 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 SG1842/43 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. The SG1842/43 is specified for
operation over the full military ambient temperature
range of -55°C to 125°C. The SG2842/43 is specified
for the industrial range of -25°C to 85°C, and the
SG3842/43 is designed for the commercial range of
0°C to 70°C.
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
Under-Voltage Lockout with 6V Hysteresis (SG1842
only)
Double-Pulse Suppression
High-Current Totem-Pole Output (1A Peak)
Internally Trimmed Bandgap Reference
500kHz Operation
Undervoltage Lockout
SG1842 - 16 volts
SG1843 - 8.4 volts
Low Shoot-Through Current <75mA Over
Temperature
Application
Available To MIL-STD
– 883, ¶ 1.2.1
Available to DSCC
- Standard Microcircuit Drawing (SMD)
Product Highlight
R
ST
AC
INPUT
I
ST
V
cc
SG3842/43
Figure 1 ·
Product Highlight
October 2014 Rev. 1.7
www.microsemi.com
© 2014 Microsemi Corporation
1
Current Mode PWM Controller
Connection Diagrams and Ordering Information
Ambient
Temperature
Type
Package
Part Number
SG3842M
0°C to 70°C
M
Packaging
Type
Connection Diagram
COM
V
FB
I
SENSE
V
REF
V
CC
OUTPUT
GND
8-PIN PLASTIC
DUAL INLINE
PACKAGE
SG3843M
Plastic DIP
SG2842M
SG2843M
R
T
/C
T
-25°C to 85°C
M PACKAGE
(Top View)
M Package:
RoHS / Pb-free 100% Matte Tin Lead Finish
0°C to 70°C
-25°C to 85°C
-55°C to
125°C
MIL-STD/883
8-PIN
CERAMIC
DUAL INLINE
PACKAGE
SG3842Y
SG3843Y
SG2842Y
SG2843Y
SG1842Y
SG1843Y
SG1842Y-883B
SG1843Y-883B
SG1842Y-DESC
CERDIP
Y
COM
V
FB
I
SENSE
R
T
/C
T
V
REF
V
CC
OUTPUT
GND
Y PACKAGE
(Top View)
PbSn Tin Lead Finish
DESC
SG1843Y-DESC
SG3842DM
0°C to 70°C
DM
-25°C to 85°C
8-PIN SMALL
OUTLINE
INTEGRATED
CIRCUIT
SG3843DM
SOIC
SG2842DM
SG2843DM
SG3842D
0°C to 70°C
D
-25°C to 85°C
SG2843D
SG3842N
0°C to 70°C
SG3843N
N
-25°C to 85°C
SG2843N
14-PIN DUAL
INLINE
PLASTIC
PACKAGE
SG2842N
PLASTIC
DIP
COM
N.C.
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
V
REF
N.C.
V
CC
V
C
OUTPUT
GND
POWER GND
COM
V
FB
I
SENSE
R
T
/C
T
V
REF
V
CC
OUTPUT
GND
DM PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
COM
N.C.
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
V
REF
N.C.
V
CC
V
C
OUTPUT
GND
PWR GND
14-PIN SMALL
OUTLINE
INTEGRATED
CIRCUIT
SG3843D
SOIC
SG2842D
D PACKAGE
(Top View)
RoHS / Pb-free 100% Matte Tin Lead Finish
N PACKAGE
(Top View)
N Package:
RoHS / Pb-free 100% Matte Tin Lead Finish
2
Connection Diagrams and Ordering Information (continued)
Connection Diagrams and Ordering Information
(continued)
Ambient
Temperature
-55°C to
125°C
14-PIN
CERAMIC
DUAL INLINE
PACKAGE
Type
Package
Part Number
SG1842J
SG1843J
SG1842J-883B
CERDIP
SG1843J-883B
SG1842J-DESC
DESC
SG1843J-DESC
-55°C to
125°C
MIL-STD/883
10-PIN
CERAMIC
FLAT PACK
PACKAGE
SG1842F
SG1843F
SG1842F-883B
SG1843F-883B
SG1842F-DESC
SG1843F-DESC
-55°C to
125°C
SG1842L
SG1843L
SG1842L-883B
MIL-STD/883
L
20-PIN
CERAMIC
SG1843L-883B
SG1842L-DESC
DESC
SG1843L-DESC
Notes:
1. Contact factory for JAN and DESC part availability.
2. All parts are viewed from the top.
3. Available in Tape & Reel. Append the letters “TR” to the part number (SG3842N-TR).
Ceramic
Leadless
Chip
Carrier
(LCC)
4
5
6
7
8
3
2
1 20 19
18
17
16
15
14
1. N.C.
2. COMP
3. N.C.
.
4. N.C.
5. V
FB
6. N.C.
7. I
SENSE
8. N.C.
9. N.C.
10. R
T
/C
T
11.
12.
13.
14.
15.
16.
17.
18.
19.
20.
N.C.
GROUND
N.C.
N.C.
OUTPUT
Packaging
Type
Connection Diagram
COM
N.C.
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
V
REF
N.C.
V
CC
V
C
OUTPUT
GND
PWR GND
MIL-STD/883
J
J PACKAGE
(Top View)
PbSn
Lead Finish
F
FLAT
PACK
COM
V
FB
I
SENSE
R
T
/C
T
PWR
GND
V
REF
V
CC
V
C
OUTPUT
GND
F PACKAGE
(Top View)
PbSn Lead Finish
DESC
N.C.
Vcc
N.C.
N.C.
V
REF
9 10 11 12 13
L PACKAGE
(Top View)
PbSn Lead Finish
3
Current Mode PWM Controller
Absolute Maximum Ratings
1 - 2
Parameter
Supply Voltage (I
CC
< 30mA)
Supply Voltage (Low Impedance Source)
Output Current (Peak)
Output Current (Continuous)
Output Energy (Capacitive Load)
Analog Inputs (V
FB
, I
SENSE
)
Error Amplifier Output Sink Current
Power Dissipation at T
A
= 25°C (DIL-8)
Operating Junction Temperature
Hermetic (J, Y, F, L Packages)
Plastic (N, M, D, DM Packages)
Storage Temperature Range
Lead Temperature (Soldering, 10 Seconds)
150
150
-65 to +150
300
°C
°C
°C
°C
°C
Value
Self-limiting
30
±1
350
5
-0.3 to +6.3
10
1
Units
V
V
A
mA
µJ
V
mA
W
RoHS / Pb-free Peak Package Solder Reflow Temp. (40 second
260 (+0, -5)
max. exposure)
Notes:
1. Exceeding these ratings could cause damage to the device.
2. All voltages are with respect to Pin 5. All currents are positive into the specified terminal.
Thermal Data
Parameter
M Package:
Thermal Resistance-Junction to Ambient, θ
JA
N Package:
Thermal Resistance-Junction to Ambient, θ
JA
DM Package:
Thermal Resistance-Junction to Ambient, θ
JA
D Package:
Thermal Resistance-Junction to Ambient, θ
JA
Y Package:
Thermal Resistance-Junction to Ambient, θ
JA
J Package
Thermal Resistance-Junction to Ambient, θ
JA
F Package
Thermal Resistance-Junction to Case, θ
JC
Thermal Resistance-Junction to Ambient, θ
JA
L Package
Thermal Resistance-Junction to Case, θ
JC
35
°C/W
°C/W
120
Thermal Resistance-Junction to Ambient, θ
JA
Notes:
1. Junction Temperature Calculation: T
J
= T
A
+ (P
D
×
θ
JA
).
2. The θ
JA
numbers are guidelines for the thermal performance of the device/pc-board system. All of the above assume no
ambient airflow.
80
145
°C/W
°C/W
80
°C/W
130
°C/W
120
°C/W
165
°C/W
65
°C/W
Value
95
Units
°C/W
4
Recommended Operating Conditions
Recommended Operating Conditions
Symbol
V
S
I
PK
I
OUT
EA
SINK
OSC
FR
R
T
C
T
Parameter
Supply Voltage Range
Output Current (Peak)
Output Current (Continuous)
Analog Inputs (V
FB
, I
SENSE
)
Error Amp Output Sink Current
Oscillator Frequency Range
Oscillator Timing Resistor
Oscillator Timing Capacitor
SG1842/43
SG2842/43
SG3842/43
Note:
Range over which the device is functional.
0.1
0.52
0.001
-55
-25
0
0
5
500
150
1.0
125
85
70
Recommended Operating Conditions
Min
Typ
30
±1
200
2.6
Max
V
A
mA
V
mA
kHz
kΩ
µF
°C
°C
°C
Units
Operating Ambient Temperature Range
5
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