LIN D
O C
#:
1825
SG1825C/SG2825C/SG3825C
H
IGH
-S
PEED
C
URRENT
-M
ODE
PWM
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
N
OT
R
ECOMMENDED
FOR
N
EW
D
ESIGNS
DESCRIPTION
The SG1825C is a high-performance
pulse width modulator optimized for
high frequency current-mode power
supplies. Included in the controller
are a precision voltage reference,
micropower start-up circuitry, soft-
start, high-frequency oscillator,
wideband error amplifier, fast current-
limit comparator, full double-pulse
suppression logic, and dual totem-
pole output drivers. Innovative
circuit design and an advanced linear
Schottky process result in very short
propagation delays through the
current limit comparator, logic, and
output drivers. This device can be
used to implement either current-
mode or voltage-mode switching
power supplies. It also is useful as
a series-resonant controller to
frequencies beyond 1MHz. The
SG1825C is specified for operation
over the full military ambient tem-
perature range of -55°C to 125°C.
The SG2825C is characterized for the
industrial range of -25°C to 85°C,
and the SG3825C is selected for the
commercial range of 0°C to 70°C.
K E Y F E AT U R E S
s
IMPROVED REFERENCE INITIAL
TOLERANCE
(±1% max.)
s
IMPROVED OSCILLATOR INITIAL
ACCURACY
(±3% typ.)
s
IMPROVED STARTUP CURRENT
(500µA typ.)
s
PROP DELAY TO OUTPUTS
(50ns typ.)
p
10V TO 30V OPERATION
p
5.1V REFERENCE TRIMMED TO ±1%
p
2MHZ OSCILLATOR CAPABILITY
p
1.5A PEAK TOTEM-POLE DRIVERS
p
U.V. LOCKOUT WITH HYSTERESIS
p
NO OUTPUT DRIVER "FLOAT"
p
PROGRAMMABLE SOFTSTART
p
DOUBLE-PULSE SUPPRESSION LOGIC
p
WIDEBAND LOW-IMPEDANCE ERROR
AMPLIFIER
p
CURRENT-MODE OR VOLTAGE-MODE
CONTROL
p
WIDE CHOICE OF HIGH-FREQUENCY
PACKAGES
PRODUCT HIGHLIGHT
I
N I T I A L
O
S C I L L AT O R
A
C C U R A C Y
15
Percentage of Units - %
Sample Size = 45
279
Mean 411.887
401.661
Std. Dev. = 4.3
3.8
HIGH RELIABILITY FEATURES
s
AVAILABLE TO MIL-STD-883B
s
LINFINITY LEVEL "S" PROCESSING AVAIL.
10
5
0
390
395
400
405
410
415
Initial Oscillator Accuracy - KHz
PACKAGE ORDER INFORMATION
T
J
(°C)
0 to 70
-25 to 85
-55 to 125
MIL-STD-883
DESC
N
Plastic DIP
16-pin
SG3825CN
SG2825CN
DW
Plastic Wide SOIC
Q
Plastic LCC
16-pin
20-pin
SG3825CDW
SG2825CDW
SG3825CQ
SG2825CQ
J
Ceramic DIP
16-pin
SG3825CJ
SG2825CJ
SG1825CJ
SG1825CJ/883B
SG1825CJ/DESC
L
Ceramic LCC
20-pin
SG1825CL
SG1825CL/883B
SG1825CL/DESC
Note: All surface-mount packages are available in Tape & Reel.
Append the letter "T" to part number. (i.e. SG3825CDWT)
FOR FURTHER INFORMATION CALL (714) 898-8121
Copyright © 1994
Rev. 1.3 6/96
11861 W
ESTERN
A
VENUE
, G
ARDEN
G
ROVE
, CA. 92841
1
PRODUCT DATABOOK 1996/1997
SG1825C/SG2825C/SG3825C
H
IGH
- S
PEED
C
URRENT
-M
O D E
PWM
N
OT
R
ECOMMENDED
A B S O L U T E M A X I M U M R AT I N G S
FOR
N
EW
D
ESIGNS
PACKAGE PIN OUTS
INV. INPUT
N.I. INPUT
E/A OUTPUT
CLOCK
R
T
C
T
RAMP
SOFTSTART
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
(Note 1)
Input Voltage (V
IN
and V
C
) .......................................................................................... 30V
Analog Inputs:
Error Amplifier and Ramp ........................................................................ -0.3V to 7.0V
Softstart and I
LIM
/S.D. ................................................................................ -0.3V to 6.0V
Digital Input (Clock) .................................................................................... 1.5V to 6.0V
Driver Outputs ........................................................................................ -0.3V to V
C
+1.5V
Source / Sink Output Current (each output):
Continuous .............................................................................................................. 0.5A
Pulse, 500ns ............................................................................................................ 2.0A
Softstart Sink Current ................................................................................................ 20mA
Clock Output Current ................................................................................................. 5mA
Error Amplifier Output Current ................................................................................. 5mA
Oscillator Charging Current ....................................................................................... 5mA
Operating Junction Temperature:
Hermetic (J, L Package) ....................................................................................... 150°C
Plastic (DW, N, Q 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.
V
REF
+V
IN
OUTPUT B
V
C
PWR GND
OUTPUT A
GROUND
I
LIM
/ S.D.
J & N PACKAGE
(Top View)
INV. INPUT
N.I. INPUT
E/A OUTPUT
CLOCK
R
T
C
T
RAMP
SOFTSTART
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
+V
REF
+V
IN
OUTPUT B
V
C
PWR GND
OUTPUT A
GROUND
I
LIM
/ S.D.
DW PACKAGE
(Top View)
3
2
1
20 19
T H E R M A L D ATA
N PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
DW PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
Q PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT,
θ
JA
J PACKAGE:
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
4
5
6
7
8
4
18
17
16
15
14
9
10 11 12 13
65°C/W
95°C/W
80°C/W
80°C/W
5
6
7
8
Q PACKAGE
(Top View)
3
2
1 20 19
18
17
16
15
14
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.
9 10 11 12 13
L PACKAGE
(Top View)
1. N.C.
2. INV. INPUT
3. N.I. INPUT
4. E/A OUTPUT
5. CLOCK
6. N.C.
7. R
T
8. C
T
9. RAMP
10. SOFTSTART
11. N.C.
12. I
LIM
/ S.D.
13. GROUND
14. OUTPUT A
15. PWR GND
16. N.C.
17. V
C
18. OUTPUT B
19. +V
IN
20. V
REF
2
Copyright © 1994
Rev. 1.3 6/96
PRODUCT DATABOOK 1996/1997
SG1825C/SG2825C/SG3825C
H
IGH
-S
PEED
C
URRENT
-M
ODE
PWM
N
OT
R
ECOMMENDED
FOR
N
EW
D
ESIGNS
(Note 2)
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
Voltage Amp Common Mode Range
Ramp Input Voltage Range
Current Limit / Shutdown Voltage Range
Source / Sink Output Current
Continuous
Pulse, 500ns
Voltage Reference Output Current
Oscillator Frequency Range
Oscillator Charging Current
Oscillator Timing Resistor
Oscillator Timing Capacitor
Operating Ambient Temperature Range:
SG1825C
SG2825C
SG3825C
Note 2. Range over which the device is functional.
Symbol
Recommended Operating Conditions
Min.
Typ.
Max.
10
1.5
0
0
200
1.0
1
4
0.030
1
0.470
0
-25
-55
10
1500
3
100
10
70
85
125
30
5.5
5.0
4.0
Units
V
V
V
V
mA
A
mA
kHz
mA
kΩ
nF
°C
°C
°C
R
T
C
T
T
A
T
A
T
A
ELECTRICAL CHARACTERISTICS
(Note 3)
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG3825C with 0°C
≤
T
A
≤
70°C, SG2825C with
-25°C
≤
T
A
≤
85°C, SG1825C with -55°C
≤
T
A
≤
125°C, and V
IN
=V
C
=15V. 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 3)
Total Output Range (Note 3)
Output Noise Voltage (Note 3)
Long Term Stability (Notes 3 &4)
Short Circuit Current
Oscillator Section
(Note 5)
Initial Accuracy
Voltage Stability
Temperature Stability (Note 3)
Total Frequency Limits (Note 3)
Minimum Frequency
Maximum Frequency
Clock High Level
Clock Low Level
Ramp Peak Voltage
Ramp Valley Voltage
Valley-to-Peak Amplitude
Symbol
Test Conditions
T
J
= 25°C, I
L
= 1mA
V
IN
= 10 to 30V
I
L
= 1 to 10mA
Over Operating Temperature
Over Line, Load, and Temperature
f = 10Hz to 10kHz, I
L
= 0mA
T
J
= 125°C, t = 1000hrs
V
REF
= 0V
T
J
= 25°C, C
CLK
≤
10pF
V
IN
= 10 to 30V
Over Rated Operating Temperature
Over Line and Temperature
R
T
= 100KΩ, C
T
= 0.01µF
R
T
= 1KΩ, C
T
= 470pF
I
CLK
= -1mA
I
CLK
= -1mA
SG1825C/2825C
SG3825C
Units
Min. Typ. Max. Min. Typ. Max.
5.05 5.10 5.15 5.05 5.10 5.15
2
15
2
15
5
15
5
15
0.2 0.4
0.2 0.4
5.00
5.20 5.00
5.20
50 200
50
5
25
5
25
-15 -50 -100 -15 -50 -100
370
400
0.2
5
430
2
8
450
4
370
400
0.2
5
430
2
8
450
4
V
mV
mV
mV/°C
V
µV
RMS
mV
mA
kHz
%
%
kHz
kHz
MHz
V
V
V
V
V
350
1.5
3.9
2.6
0.7
1.6
350
1.5
3.9
4.5
2.3
2.8
1.0
1.8
2.9
3.0
1.25
2.0
2.6
0.7
1.6
4.5
2.3
2.8
1.0
1.8
2.9
3.0
1.25
2.0
Note 3. This parameter is guaranteed by design and process control, but is not 100% tested in production.
Note 4. This parameter is non-accumulative, and represents the random fluctuation of the reference voltage within some error band when observed
over any 1000 hour period of time.
Copyright © 1994
Rev. 1.3 6/96
3
PRODUCT DATABOOK 1996/1997
SG1825C/SG2825C/SG3825C
H
IGH
- S
PEED
C
URRENT
-M
O D E
PWM
N
OT
R
ECOMMENDED
FOR
N
EW
D
ESIGNS
(Cont'd.)
ELECTRICAL CHARACTERISTICS
Parameter
Error Amplifier Section
(Note 6)
Input Offset Voltage
Input Bias Current
Input Offset Current
DC Open Loop Gain
Common Mode Rejection
Power Supply Rejection
Output Sink Current
Output Source Current
Output High Voltage
Output Low Voltage
Unity Gain Bandwidth (Note 3)
Slew Rate (Note 3)
Ramp Input Bias Current
Minimum Duty Cycle
Maximum Duty Cycle (Note 8)
Zero Duty Cycle Threshold
Delay to Driver Output (Note 3)
R
S
≤
2KΩ, V
ERROR
= 2.5V
V
ERROR
= 2.5V
V
ERROR
= 2.5V
V
ERROR
= 1 to 4V
Over Rated Voltage Range, V
ERROR
= 2.5V
V
IN
= 10V to 30V, V
ERROR
= 2.5V
V
ERROR
= 1V
V
ERROR
= 4V
I
ERROR
= -0.5mA
I
ERROR
= 1mA
A
VOL
= 0dB
Symbol
Test Conditions
SG1825C/2825C
SG3825C
Units
Min. Typ. Max. Min. Typ. Max.
15
3
1
60
75
85
1
-0.5
4.0
0
3
6
15
3
1
mV
µA
µA
dB
dB
dB
mA
mA
V
V
MHz
V/µsec
µA
%
%
V
ns
µA
mA
µA
V
V
ns
V
V
V
V
µA
ns
V
V
mA
mA
A
VOL
60
75
85
1
-0.5
4.0
0
3
6
0.6
0.1
95
95
110
2.5
-1.3
4.7
0.5
5.5
5.0
1.0
0.6
0.1
95
95
110
2.5
-1.3
4.7
0.5
5.5
5.0
1.0
PWM Comparator Section
(Note 5 & 7)
-1
V
ERROR
= 1V
V
ERROR
= 4V
V
RAMP
= 0V to 2V, V
ERROR
= 2V
V
SOFTSTART
= 0.5V
V
SOFTSTART
= 1.0V
3
1
85
1.1
-5
0
85
1.1
80
20
3
1
-1
-5
0
1.25
50
9
1.25
50
9
80
20
Softstart Section
C
SS
Charge Current
C
SS
Discharge Current
Current Limit / Shutdown Section
(Note 9)
I
LIM
Input Bias Current
Current Limit Threshold
Shutdown Threshold
Delay to Driver Output (Note 3)
±15
±10
0.9 1.0 1.1 0.9 1.0 1.1
1.25 1.40 1.55 1.20 1.40 1.55
50
80
50
80
0.25 0.40
0.25 0.40
1.2 2.0
1.2 2.0
13.0 13.5
13.0 13.5
12.0 13.0
12.0 13.0
150 500
150 500
30
60
30
60
8.8
0.4
V
IN
= 8V
V
INV
, V
RAMP
, V(I
LIM
/S.D.) = 0V, V
N.I.
= 1V
9.2
0.8
0.5
22
9.7
1.2
1.2
33
8.8
0.4
9.2
0.8
0.5
22
9.7
1.2
1.2
33
V
SHUTDOWN
= 0V to 1.2V
I
SINK
= 20mA
I
SINK
= 200mA
I
SOURCE
= 20mA
I
SOURCE
= 200mA
V
C
= 30V
C
L
= 1000pF
Output Drivers Section (each output)
Output Low Level
Output High Level
V
C
Standby Current
Output Rise / Fall Time (Note 3)
Undervoltage Lockout Section
Start Threshold Voltage
UV Lockout Hysteresis
Supply Current Section
(Note 5)
Start Up Current
Operating Current
Note
Note
Note
Note
Note
5. F
OSC
= 400kHz (R
T
= 3.65kΩ, C
T
= 1.0nF).
6. V
CM
= 1.5V to 5.5V.
7. V
RAMP
= 0V, unless otherwise specified.
8. 100% duty cycle is defined as a pulsewidth equal to one oscillator period.
9. V(I
LIM
/S.D.) = 0V to 4.0V, unless otherwise specified.
4
Copyright © 1994
Rev. 1.3 6/96
PRODUCT DATABOOK 1996/1997
SG1825C/SG2825C/SG3825C
H
IGH
-S
PEED
C
URRENT
-M
ODE
PWM
N
OT
R
ECOMMENDED
FOR
N
EW
D
ESIGNS
BLOCK DIAGRAM
V
REF
+9V
16
13
V
C
11
OUTPUT A
+V
IN
15
GND
10
CLOCK
4
REFERENCE
REGULATOR
+ 4.0V
Q
T
Q
14
OUTPUT B
R
T
5
OSCILLATOR
C
T
6
1.25V
RAMP
7
E/A OUTPUT
3
N.I. INPUT
2
ERROR
INV. INPUT
1
9µA
SOFTSTART
8
+ 1.0V
S
R Q
12
POWER GND
9
I
LIM
/S.D.
+ 1.4V
FIGURE INDEX
Application Circuits
FIGURE #
1.
2.
3.
4.
5.
6.
7.
HIGH-SPEED LAYOUT AND BYPASSING
MICROPOWER STARTUP
SOFTSTART FAST RESET
OSCILLATOR SYCHRONIZATION
OSCILLATOR FUNCTIONAL DIAGRAM
VOLTAGE AMPLIFIER CONNECTIONS
DRIVING SHIELDED CABLE
Copyright © 1994
Rev. 1.3 6/96
5
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