L I N D
O C
# :
1842
SG1842/SG1843 Series
C
URRENT
M
ODE
PWM C
ONTROLLER
T
H E
I
N F I N I T E
P
O W E R
O F
I
N N O VA T I O N
P
R O D U C T I O N
D
A T A
S
H E E T
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.
K E Y F E AT U R E S
s
OPTIMIZED FOR OFF-LINE CONTROL
s
LOW START-UP CURRENT (<1mA)
s
AUTOMATIC FEED FORWARD
COMPENSATION
s
TRIMMED OSCILLATOR DISCHARGE
CURRENT
s
PULSE-BY-PULSE CURRENT LIMITING
s
ENHANCED LOAD RESPONSE
CHARACTERISTICS
s
UNDER-VOLTAGE LOCKOUT WITH 6V
HYSTERESIS (SG1842 only)
s
DOUBLE-PULSE SUPPRESSION
s
HIGH-CURRENT TOTEM-POLE OUTPUT
(1AMP PEAK)
s
INTERNALLY TRIMMED BANDGAP
REFERENCE
s
500KHZ OPERATION
s
UNDERVOLTAGE LOCKOUT
SG1842 - 16 volts
SG1843 - 8.4 volts
s
LOW SHOOT-THROUGH CURRENT <75mA
OVER TEMPERATURE
PRODUCT HIGHLIGHT
T
Y P I C A L
A
P P L I C AT I O N
OF
S G 3 8 4 2 I
N
A F
LY B A C K
C
O N V E R T E R
R
ST
HIGH RELIABILITY FEATURES
s
AVAILABLE TO MIL-STD-883B AND DESC
SMD
s
SCHEDULED FOR MIL-M38510 QPL LISTING
s
RADIATION DATA AVAILABLE
s
LINFINITY LEVEL "S" PROCESSING AVAILABLE
AC
INPUT
I
ST
V
CC
SG3842
T
A
(°C)
0 to 70
-25 to 85
-55 to 125
MIL-STD/883
DESC
M
8-pin
Plastic DIP
N
PA C K A G E O R D E R I N F O R M AT I O N
Plastic DIP
Plastic SOIC
Plastic SOIC
Ceramic DIP
Ceramic DIP
DM
8-pin
D
14-pin
Y
8-pin
J
14-pin
14-pin
SG3842N
SG3843N
SG2842N
SG2843N
—
—
—
—
—
SG3842DM
SG3843DM
SG2842DM
SG2843DM
—
—
—
—
—
SG3842D
SG3843D
SG2842D
SG2843D
—
—
—
—
—
SG3842Y
SG3843Y
SG2842Y
SG2843Y
SG1842Y
SG1843Y
SG3842J
SG3843J
SG2842J
SG2843J
SG1842J
SG1843J
F
10-pin
—
—
—
—
—
—
—
—
Cer. Flatpack
L
20-pin
—
—
—
—
Ceramic LCC
SG3842M
SG3843M
SG2842M
SG2843M
—
—
—
—
—
SG1842L
SG1843L
SG1842L/883B
SG1843L/883B
SG1842Y/883B SG1842J/883B
SG1843Y/883B SG1843J/883B
SG1842Y/DESC SG1842J/DESC
SG1842F/DESC SG1842L/DESC
SG1843F/DESC SG1843L/DESC
—
—
SG1843Y/DESC SG1843J/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. 1.6 4/00
11861 W
ESTERN
A
VENUE
, G
ARDEN
G
ROVE
, CA. 92841
1
PRODUCT DATABOOK 1996/1997
SG1842/SG1843 Series
C
URRENT
-M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
A B S O L U T E M A X I M U M R AT I N G S
(Notes 1 & 2)
PACKAGE PIN OUTS
COMP
V
FB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
Supply Voltage (I
CC
< 30mA) ............................................................... Self Limiting
Supply Voltage (Low Impedance Source) ........................................................ 30V
Output Current (Peak) ....................................................................................... ±1A
Output Current (Continuous) ....................................................................... 350mA
Output Energy (Capacitive Load) ....................................................................... 5µJ
Analog Inputs (Pins 2, 3) ................................................................. -0.3V to +6.3V
Error Amp Output Sink Current ..................................................................... 10mA
Power Dissipation at T
A
= 25°C (DIL-8) ............................................................ 1W
Operating Junction Temperature
Hermetic (J, Y, F, L Packages) ................................................................... 150°C
Plastic (N, M, D, DM Packages) ................................................................ 150°C
Storage Temperature Range .......................................................... -65°C to +150°C
Lead Temperature (Soldering, 10 Seconds) .................................................. 300°C
Note 1. Exceeding these ratings could cause damage to the device.
Note 2. All voltages are with respect to Pin 5. All currents are positive into the specified
terminal.
V
REF
V
CC
OUTPUT
GND
M & Y PACKAGE
(Top View)
COMP
V
FB
I
SENSE
R
T
/C
T
1
2
3
4
8
7
6
5
V
REF
V
CC
OUTPUT
GND
DM PACKAGE
(Top View)
COMP
N.C.
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
1
2
3
4
5
6
7
14
13
12
11
10
9
8
T H E R M A L D ATA
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
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
35°C/W
120°C/W
3
2
V
REF
N.C.
V
CC
V
C
OUTPUT
GND
PWR GND
95°C/W
65°C/W
165°C/W
120°C/W
130°C/W
80°C/W
80°C/W
145°C/W
D PACKAGE
(Top View)
COMP
N.C.
V
FB
N.C.
I
SENSE
N.C.
R
T
/C
T
1
2
3
4
5
6
7
14
13
12
11
10
9
8
V
REF
N.C.
V
CC
V
C
OUTPUT
GROUND
POWER GND
J & N PACKAGE
(Top View)
1. COMP
2. V
FB
3. I
SENSE
4. R
T
/C
T
5. POWER GND
1
2
3
4
5
10
9
8
7
6
10.V
REF
9. V
CC
8. V
C
7. OUTPUT
6. GND
F PACKAGE
(Top View)
1 20 19
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x
θ
JA
).
The
θ
JA
numbers are guidelines for the thermal performance of the device/pc-board
system. All of the above assume no ambient airflow.
4
5
6
7
8
18
17
16
15
14
9 10 11 12 13
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
N.C.
V
CC
N.C.
N.C.
V
REF
L PACKAGE
(Top View)
2
Copyright © 2000
Rev. 1.6 4/00
PRODUCT DATABOOK 1996/1997
SG1842/SG1843 Series
C
URRENT
-M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
R E C O M M E N D E D O P E R AT I N G C O N D I T I O N S
Parameter
Supply Voltage Range
Output Current (Peak)
Output Current (Continuous)
Analog Inputs (Pin 2, Pin 3)
Error Amp Output Sink Current
Oscillator Frequency Range
Oscillator Timing Resistor
Oscillator Timing Capacitor
Operating Ambient Temperature Range:
SG1842/43
SG2842/43
SG3842/43
Note 3. Range over which the device is functional.
(Note 3)
Symbol
Recommended Operating Conditions
Min.
Typ.
Max.
30
±1
200
0
5
0.1
0.52
0.001
-55
-25
0
2.6
500
150
1.0
125
85
70
Units
V
A
mA
V
mA
kHz
KΩ
µF
°C
°C
°C
R
T
C
T
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG1842/SG1843 with -55°C
≤
T
A
≤
125°C, SG2842/
SG2843 with -25°C
≤
T
A
≤
85°C, SG3842/SG3843 with 0°C
≤
T
A
≤
70°C, V
CC
= 15V (Note 7), R
T
= 10kΩ, and C
T
= 3.3nF. Low duty cycle pulse testing
techniques are used which maintains junction and case temperatures equal to the ambient temperature.)
Parameter
Reference Section
Output Voltage
Line Regulation
Load Regulation
Temperature Stability (Note 4)
Total Output Variation (Note 4)
Output Noise Voltage (Note 4)
Long Term Stability (Note 4)
Output Short Circuit
Symbol
Test Conditions
SG1842/43
SG2842/43
SG3842/43
Units
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
4.95 5.00 5.05 4.95 5.00 5.05 4.90 5.00 5.10
6
20
6
20
6
20
6
25
6
25
6
25
0.2 0.4
0.2 0.4
0.2 0.4
4.90
5.10 4.90
5.10 4.82
5.18
50
50
50
5
25
5
25
5
25
-30 -100 -180 -30 -100 -180 -30 -100 -180
47
52
0.2
5
1.7
8.3
57
1
47
52
0.2
5
1.7
8.4
57
1
47
52
0.2
5
1.7
8.4
57
1
V
mV
mV
mV/°C
V
µV
mV
mA
kHz
%
%
V
mA
mA
V
µA
dB
MHz
dB
mA
mA
V
V
T
J
= 25°C, I
O
= 1mA
12
≤
V
IN
≤
25V
1
≤
I
O
≤
20mA
Line, Load, Temp.
10Hz
≤
f
≤
10kHz, T
J
= 25°C
T
A
= 125°C, 1000hrs
V
N
Oscillator Section
Initial Accuracy
Voltage Stability
Temperature Stability (Note 4)
Amplitude
Discharge Current
T
J
= 25°C
12
≤
V
CC
≤
25V
T
MIN
≤
T
A
≤
T
MAX
V
RT/CT
(Peak to Peak)
T
J
= 25°C
T
MIN
≤
T
A
≤
T
MAX
V
COMP
= 2.5V
A
VOL
PSRR
2
≤
V
O
≤
4V
T
J
= 25°C
12
≤
V
CC
≤
25V
V
VFB
= 2.7V, V
COMP
= 1.1V
V
VFB
= 2.3V, V
COMP
= 5V
V
VFB
= 2.3V, R
L
= 15K to gnd
V
VFB
= 2.7V, R
L
= 15K to V
REF
7.8
7.0
8.8
9.0
7.5
7.2
9.3
9.5
7.5
7.2
9.3
9.5
Error Amp Section
Input Voltage
Input Bias Current
Open Loop Gain
Unity Gain Bandwidth (Note 4)
Power Supply Rejection Ratio
Output Sink Current
Output Source Current
V
OUT
High
V
OUT
Low
2.45 2.50 2.55 2.45 2.50 2.55 2.42 2.50 2.58
-0.3 -1
-0.3
1
-0.3 -2
65
90
65
90
65
90
0.7
1
0.7
1
0.7
1
60
70
60
70
60
70
2
6
2
6
2
6
-0.5 -0.8
-0.5 -0.8
-0.5 -0.8
5
6
5
6
5
6
0.7 1.1
0.7 1.1
0.7 1.1
(Electrical Characteristics continue next page.)
Copyright © 2000
Rev. 1.6 4/00
3
PRODUCT DATABOOK 1996/1997
SG1842/SG1843 Series
C
URRENT
-M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
ELECTRICAL CHARACTERISTICS
Parameter
Current Sense Section
Gain (Notes 5 & 6)
Maximum Input Signal (Note 5)
Power Supply Rejection Ratio (Note 5) PSRR
Input Bias Current
Delay to Output (Note 4)
V
COMP
= 5V
12
≤
V
CC
≤
25V
2.85
0.9
3
1
70
-2
150
0.1
1.5
13.5
13.5
50
50
16
8.4
10
7.6
95
(Cont'd.)
Symbol
Test Conditions
SG1842/43
SG2842/43
SG3842/43
Units
Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
3.15 2.85
1.1 0.9
-10
300
0.4
2.2
13
12
150
150
17
9.0
11
8.3
100
0
1
17
15
7.8
9
7.0
90
3
1
70
-2
150
0.1
1.5
13.5
13.5
50
50
16
8.4
10
7.6
95
3.15 2.85
1.1 0.9
-10
300
0.4
2.2
13
12
150
150
17
9.0
11
8.2
100
0
14.5
7.8
8.5
7.0
90
3
1
70
-2
150
0.1
1.5
13.5
13.5
50
50
16
8.4
10
7.6
95
3.15
1.1
-10
300
0.4
2.2
V/V
V
dB
µA
ns
V
V
V
V
ns
ns
V
V
V
V
%
%
Output Section
Output Low Level
Output High Level
Rise Time
Fall Time
I
SINK
= 20mA
I
SINK
= 200mA
I
SOURCE
= 20mA
I
SOURCE
= 200mA
T
J
= 25°C, C
L
= 1nF
T
J
= 25°C, C
L
= 1nF
1842
1843
1842
1843
13
12
150
150
17.5
9.0
11.5
8.2
100
0
Under-Voltage Lockout Section
Start Threshold
Min. Operation Voltage After Turn-On
15
7.8
9
7.0
93
PWM Section
Maximum Duty Cycle
Minimum Duty Cycle
Power Consumption Section
Start-Up Current
Operating Supply Current
V
CC
Zener Voltage
V
FB
= V
ISENSE
= 0V
I
CC
= 25mA
0.5
1
0.5
1
mA
11
17
11
17
mA
34
34
V
∆
V
6. Gain defined as: A =
∆
V
COMP
; 0
≤
V
ISENSE
≤
0.8V.
ISENSE
7. Adjust V
CC
above the start threshold before setting at 15V.
0.5
11
34
Notes: 4. These parameters, although guaranteed, are not 100% tested in
production.
5. Parameter measured at trip point of latch with V
VFB
= 0.
4
Copyright © 2000
Rev. 1.6 4/00
PRODUCT DATABOOK 1996/1997
SG1842/SG1843 Series
C
URRENT
-M
ODE
PWM C
ONTROLLER
P
R O D U C T I O N
D
A T A
S
H E E T
BLOCK DIAGRAM
V
CC
*
34V
UVLO
S/R
5V
REF
GROUND**
16V (1842)
8.4V (1843)
2.5V
6V (1842)
0.8V (1843)
V
REF
5.0V
50mA
INTERNAL
BIAS
V
REF
GOOD LOGIC
R
T
/C
T
OSCILLATOR
V
C
*
OUTPUT
ERROR AMP
2R
R
1V
S
R
CURRENT SENSE
COMPARATOR
PWM
LATCH
POWER GROUND**
V
FB
COMP
CURRENT SENSE
* - V
CC
and V
C
are internally connected for 8 pin packages.
** - POWER GROUND and GROUND are internally connected for 8 pin packages.
Copyright © 2000
Rev. 1.6 4/00
5
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