SG1825C
High Speed Current Mode PWM
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, micro power 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
temperature range of -55°C to 125°C.
Features
Improved Reference Initial Tolerance (±1% max.)
Improved Oscillator Initial Accuracy (±3% typ.)
Improved Startup Current (500μA typ.)
Propagation Delay to Outputs (50ns typ.)
10V to 30V Operation
5.1V Reference Trimmed to ±1%
2MHz Oscillator Capability
1.5A Peak Totem-Pole Drivers
U.V. Lockout with Hysteresis
No Output Driver “FLOAT”
Programmable Softstart
Double-Pulse Suppression Logic
Wideband Low-Impedance Error Amplifier
Current-Mode or Voltage-Mode Control
High Reliability Features
Available To MIL-STD-883 – 883, ¶ 1.2.1
Available to DSCC
– Standard Microcircuit Drawing (SMD)
SGR1825C Rad-Tolerant Version Available
Product Highlight
15
Sample Size = 279
Mean 401.661
Std. Dev. = 3.8
Percentage of Units - %
10
5
0
390
395
400
405
410
415
Initial Oscillator Accuracy - kHz
Figure 1 ·
Product Highlight
November 2014 Rev. 1.4
www.microsemi.com
© 2014 Microsemi Corporation- Analog Mixed Signal Group
1
High Speed Current Mode PWM
Connection Diagrams and Ordering Information
Ambient
Temperature
Type
Package
Part Number
Packaging
Type
Connection Diagram
SG1825CJ
INV. INPUT
N.I.INPUT
E/A OUTPUT
V
REF
+V
IN
OUTPUT B
-55°C to
125°C
J
16-PIN
CERAMIC
DUAL INLINE
PACKAGE
CLOCK
V
C
PWR GND
OUTPUT A
GROUND
I
LIM
/S.D.
SG1825CJ-883B
R
T
CERDIP
C
T
RAMP
SOFTSTART
SG1825CJ-DESC
J Package
(Top View)
3
2
1 20 19
18
17
16
15
14
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. GND
14.OUTPUT A
15.PWR GND
16.
N.C.
17. Vc
18. OUTPUT B
19.+V
IN
20. V
REF
SG1825CL
20-Pin
CERAMIC
Leadless Chip
Carrier
4
5
6
7
-55°C to
125°C
L
SG1825CL-883B
CLCC
8
9 10 11 12 13
Figure 2 ·
SG1825CL-DESC
L PACKAGE
(Top View)
Notes:
1. Contact factory for DESC part availability.
2. All parts are viewed from the top.
3. Hermetic Packages J, & L use Pb37/Sn63 hot solder lead finish, contact factory for availability of RoHS versions.
2
Absolute Maximum Ratings1
Absolute Maximum Ratings
1
Parameter
Input Voltage (V
IN
and V
C
)
Analog Inputs:
Error Amplifier and Ramp
Softstart and ILIM/S.D.
Digital Input (Clock)
Driver Outputs
Source / Sink Output Current (each output):
Continuous
Pulse, 500ns
Softstart Sink Current
Clock Output Current
Error Amplifier Output Current
Oscillator Charging Current
Operating Junction Temperature:
Hermetic (J, L Package)
Storage Temperature Range
Lead Temperature (soldering, 10 seconds)
Peak Package Solder Reflow Temp. (40 seconds max. exposure)
Notes:
1. Exceeding these ratings could cause damage to the device.
150
-65 to 150
300
260 (+0, -5)
°C
°C
°C
°C
0.5
2.0
20
5
5
5
A
A
mA
mA
mA
mA
-0.3 to 7.0
0.3 to 6.0
1.5 to 6.0
-0.3 to V
C
+1.5
V
V
V
V
Value
30
Units
V
Thermal Data
Parameter
J 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
Thermal Resistance-Junction to Ambient, θ
JA
120
Notes:
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.
30
80
°C/W
°C/W
Value
Units
3
High Speed Current Mode PWM
Recommended Operating Conditions
2
Symbol
V
IN
Parameter
Supply Voltage Range
Voltage Amp Common Mode Range
Ramp Input Voltage Range
Current Limit I Shutdown Voltage Range
Source / Sink Output Current:
Continuous
Pulse, 500ns
Voltage Reference Output Current
Oscillator Frequency Range
Oscillator Charging Current
R
T
C
T
T
A
Oscillator Timing Resistor
Oscillator Timing Capacitor
SG1825C
1
4
0.030
1
0.470
-55
200
1.0
10
1500
3
100
10
125
mA
A
mA
kHz
mA
kΩ
nF
°C
Recommended Operating Conditions
Min.
10
1.5
0
0
Typ.
Units
V
V
V
V
Max.
30
5.5
5.0
4.0
Operating Ambient Temperature Range:
Notes:
2. Range over which the device is functional.
4
Electrical Characteristics
Electrical Characteristics
Unless otherwise specified, these specifications apply over the full operating ambient temperatures of -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.
Symbol
Parameter
Output Voltage
Line Regulation
Load Regulation
Temperature Stability
Total Output Range
3
3
3
Test Conditions
T
J
= 25°C, I
L
= 1mA
V
IN
= 10V to 30V
I
L
= 1mA to 10mA
Over Operating Temperature
Over Line, Load, and Temperature
f = 10Hz to 10kHz,
I
L
= 0mA
T
J
= 125 °C, t = 1000 hrs
V
REF
= 0V
Min.
Typ.
Max
Units
V
mV
mV
mV/°C
V
µV
RMS
mV
mA
Reference Section
5.05
5.10
2
5
0.2
5.00
50
5
-15
-50
5.15
15
15
0.4
5.20
200
25
-100
Output Noise Voltage
Long Term Stability
5
3 and 4
Short Circuit Current
Oscillator Section
Initial Accuracy
Voltage Stability
Temperature Stability
3
T
J
= 25°C, C
CLK
≤ 10pF
V
IN
= 10V to 30V
Over Rated Operating
Temperature
3
370
400
0.2
5
430
2
8
450
4
kHz
%
%
kHz
kHz
MHz
Total Frequency Limits
Minimum Frequency
Maximum Frequency
Clock High Level
Clock Low Level
Ramp Peak Voltage
Ramp Valley Voltage
Over Line and Temperature
R
T
= 100kΩ, C
T
= 0.01µF
R
T
= 1kΩ, C
T
= 470pF
I
CLK
= -1mA
I
CLK
= -1mA
350
1.5
3.9
4.5
2.3
2.6
0.7
1.6
2.8
1.0
1.8
2.9
3.0
1.25
2.0
V
V
V
V
V
Valley-to-Peak Amplitude
Error Amp Section
6
Input Offset Voltage
Input Bias Current
Input Offset Current
R
S
≤ 2k, V
ERROR
= 2.5V
V
ERROR
= 2.5V
V
ERROR
= 2.5V
V
ERROR
= 1V 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
3
15
0.6
0.1
60
75
85
1
-0.5
4.0
0
3
6
95
95
110
2.5
-1.3
4.7
0.5
5.5
5.0
1.0
3
1
mV
µA
µA
dB
dB
dB
mA
mA
V
V
MHz
V/µsec
A
VOL
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
Slew Rate
3
A
VOL
= 0dB
5
Switching Power Supply Study Group
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