SG1846/SG2846/SG3846
Current Mode PWM Controller
Description
The SG1846 family of control ICs provides the required
features to implement Fixed Frequency, Current mode
control schemes while maintaining a minimum external
parts count.
The advanced performance of this
technique can be measured in improved line regulation,
enhanced load response characteristics, and a simpler,
easier-to-design control loop. Topological advantages
include, inherent pulse-by-pulse current limiting
capability, automatic symmetry correction for push-pull
converters, and the ability to parallel “power modules”
while maintaining equal current sharing.
Protection circuitry includes built-in under-voltage
lockout and programmable current limit in addition to
soft start capability. A shutdown function is also
available which can initiate either a complete shutdown
with automatic restart, or latch the supply off.
Other features include fully latched operation, double-
pulse suppression, dead-time adjust capability, and a
±1% trimmed bandgap reference.
Features
Automatic Feed-forward Compensation
Programmable Pulse by Pulse Current Limiting
Automatic Symmetry Correction in Push-pull
Configuration
Enhanced Load Response Characteristics
Parallel Operation Capability for Modular Power
Systems
Differential Current Sense Amplifier with Wide
Common-mode Range
Double Pulse Suppression
200mA Totem-pole Outputs
± 1% Bandgap Reference
Under-voltage Lockout
Soft-start and Shutdown Capability
500kHz Operation
High Reliability Features
Available To MIL-STD-883 – 883, ¶ 1.2.1
Available to DSCC
– Standard Microcircuit Drawing (SMD)
SGR1846 Rad-Tolerant Version Available
Block Diagram
V
IN
SYNC
R
T
C
T
OSC
5.1 V
REFERENCE
REGULATOR
VREF
U.V.LOCKOUT
VC
Q
T
-
Q
A OUT
-CURRENT
SENSE
+CURRENT
SENSE
-
X3
+
-
S
+
COMP
S R
Q
SG1846
Output Stoge
B OUT
GND
0.5 V
0.5 mA
CURRENT LIMITADJUST
+
-
N.I.
INV.
COMP
SHUTDOWN
6K
350 mV
+
E.A.
-
Figure 1 ·
Block Diagram
November 2014 Rev. 1.2
www.microsemi.com
© 2014 Microsemi Corporation- Analog Mixed Signal Group
1
Current Mode PWM Controller
Connection Diagrams and Ordering Information
Ambient
Temperature
Type
Package
Part Number
Packaging
Type
Connection Diagram
-55°C to 125°C
J
16-PIN
CERAMIC
DUAL INLINE
PACKAGE
16-PIN
PLASTIC DIP
PACKAGE
16-PIN
WIDEBODY
SG1846J-883B
SG1846J-DESC
SG1846J
SG2846N
PDIP
SG3846N
CERDIP
C.L./SOFTSTART
V
REF
(-) C.S.
(+) C.S.
(+) ERROR AMP
(-) ERROR AMP
COMPENSATION
C
T
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SHUTDOWN
+V
IN
OUTPUT B
V
C
GROUND
OUTPUT A
SYNC
R
T
-25°C to 85°C
N
0°C to 70°C
N Package: RoHS Complaint / Pb-free Transition DC: 0503
N Package: RoHS / Pb-free 100% Matte Tin Lead Finish
C.L./SOFTSTART
VREF
-25°C to 85°C
DW
0°C to 70°C
SG2846DW
SOWB
(-) C.S.
(+) C.S.
(+) ERROR AMP
(-) ERROR AMP
1
2
3
4
5
6
16
15
14
13
SHUTDOWN
+V
IN
OUTPUT B
VC
PLASTIC
SOIC
PACKAGE
4
SG3846DW
12
GROUND
OUTPUT A
11
SYNC
10
7
COMPENSATION
CT
RT
8
9
DW Package: RoHS Complaint / Pb-free Transition DC: 0516
DW Package: RoHS / Pb-free 100% Matte Tin Lead Finish
16-PIN
CERAMIC
F
-55°C to 125°C
FLAT PACK
PACKAGE
3
C.L./SOFTSTART
VREF
SG1846F-DESC
FLATPAK
(-) C.S.
(+) C.S.
(+) ERROR AMP
(-) ERROR AMP
COMPENSATION
CT
1
2
3
4
5
6
7
8
16
15
14
13
12
11
10
9
SHUTDOWN
+V
IN
OUTPUT B
VC
GROUND
OUTPUT A
SYNC
RT
L
20-PIN
CERAMIC
LLC
3
PACKAGE
SG1846L-883B
SG1846L-DESC
SG1846L
CLCC
1. N.C.
2. C.L./SOFTSTART
3. V REF
4. (-) C.S.
5. (+) C.S.
6. N.C.
7. (+) ERROR AMP
8. (-) ERROR AMP
9. COMPENSATION
10. C T
3 2
4
5
6
7
8
1 20 19
18
17
16
15
14
9 10 11 12 13
11. N.C.
12. R T
13. SYNC
14. OUTPUT A
15. GROUND
16. N.C.
17. V C
18. OUTPUT B
19. V IN
20. SHUTDOWN
Notes:
1.
2.
3.
4.
5.
Contact factory for DESC part availability.
All parts are viewed from the top.
Consult factory for product availability.
The SG2846 & SG3846 is available shipped as tape & reel with the addition of a –TR suffix.
Hermetic Packages J, F, & L use Pb37/Sn63 hot solder lead finish, contact factory for availability of RoHS versions.
Absolute Maximum Ratings
Parameter
Supply Voltage (+V
IN
)
Collector Supply Voltage(V
C
)
Analog Inputs (Pins 3, 4, 5, 6, and 16)
Logic Input
Source/Sink Load current (continuous)
Source/Sink Load Current (peak, 200 ns)
Reference Load Current
Soft Start Sink Current
Sync Output Current
Error Amplifier Output Current
Oscillator Charging current (Pin 9)
Value
40
40
-0.3V to +V
IN
-0.3V to 5.5V
200
500
30
50
5
5
5
Units
V
V
V
V
mA
mA
mA
mA
mA
mA
mA
2
Thermal Data
Parameter
Operating Junction Temperature Hermetic (J, L, F Packages)
Operating Junction Temperature Plastic (N, DW Package)
Storage Temperature Range
Lead Temperature (Soldering, 10 Seconds)
RoHS Peak Package Solder Reflow Temp. (40 sec. max. exp.)
Values beyond which damage may occur.
1.
Pin numbers refer to ceramic J package.
2.
Value
150
150
-65 to 150
300
260 (+0, -5)
Units
°C
°C
°C
°C
°C
Thermal Data
Parameter
J Package:
Thermal Resistance-Junction to Case, θ
JC
Thermal Resistance-Junction to Ambient, θ
JA
N Package:
Thermal Resistance-Junction to Case, θ
JC
Thermal Resistance-Junction to Ambient, θ
JA
Value
30
80
40
65
Units
°C/W
°C/W
°C/W
°C/W
DW Package:
°C/W
Thermal Resistance-Junction to Case, θ
JC
40
°C/W
Thermal Resistance-Junction to Ambient, θ
JA
95
F Package:
°C/W
Thermal Resistance-Junction to Case, θ
JC
70
°C/W
Thermal Resistance-Junction to Ambient, θ
JA
115
L Package:
°C/W
Thermal Resistance-Junction to Case, θ
JC
35
°C/W
Thermal Resistance-Junction to Ambient, θ
JA
120
Notes:
Junction Temperature Calculation: T
J
= T
A
+ (P
D
x θ
JA
).
1.
The above numbers for θ
JC
are maximums for the limiting thermal resistance of the package in a standard mounting
2.
configuration. The θ
JA
numbers are meant to be guidelines for the thermal performance of the device/PCBoard system. All of
the above assume no ambient airflow.
Recommended Operating Conditions
Parameter
Supply Voltage Range
Collector Supply Voltage Range
Source/Sink Output Current (continuous)
Source/Sink Output Current (peak 200ns)
Reference Load Current
Oscillator Frequency Range
Oscillator Timing Resistor (R
T
)
Oscillator Timing Capacitor (C
T
)
Operating Ambient Temperature Range
SG1846
SG2846
SG3846
Note:
Range over which the device is functional.
Value
8 to 40
4.5 to 40
100
200
0 to 10
1 to 500
2 to 100
1 to 100
55 to 125
25 to 85
0 to 70
Units
V
V
mA
mA
mA
kHz
kΩ
nF
°C
°C
°C
3
Current Mode PWM Controller
Electrical Characteristics
Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG1846
with -55°C ≤ T
A
≤ 125°C, SG2846 with -25°C ≤ T
A
≤ 85°C, SG3846 with 0°C ≤ T
A
≤ 70°C, +V
IN
= 15V. Low
duty cycle pulse testing techniques are used which maintains junction and case temperatures equal to the
ambient temperature.
SG1846
SG2846
Min Typ
Reference Section
V
REF
V
REG
I
REG
Output Voltage
Line Regulation
Load Regulation
Temperature Stability
1
1
SG3846
Units
Max
Min
Typ
Max
Symbol
Parameter
Test Condition
T
J
= 25°C, I
O
= 1mA
V
IN
= 8V to 40V
I
L
= 1mA to 10mA
5.05
5.10
5
3
0.4
5.15
20
15
5.00
5.10
5
3
0.4
5.20
20
15
V
mV
mV
mV/
°C
Total Output Variation
Output Noise Voltage
Long Term Stability
VREF
ISC
1
Line, Load and Temperature
10Hz ≤ f ≤ 10kHz. T
J
= 25°C
T
J
= 125°C, 1000Hrs.
V
REF
= 0V
5.00
100
5
-10
-45
5.20
4.95
100
5
-10
-45
5.25
V
µV
mV
mA
1
Short Circuit Output
Current
6
Oscillator Section
OSC
OSC
VS
OSC
TS
VOH
VOL
VIH
VIL
IIL
Initial Accuracy
Voltage Stability
Temperature Stability
1
T
J
= 25°C
V
IN
= 8V to 40V
Over Operating Range
39
43
1
1
47
2
39
43
1
1
47
2
kHz
%
%
V
Sync Output High Level
Sync Output Low Level
Sync Input High Level
Sync Input Low Level
Sync Input Current
Pin 8 = 0V
Pin 8 = 0V
Sync Voltage = 5.25V, Pin 8
= 0V
3.9
4.35
2.3
2.5
3.9
4.35
2.3
2.5
V
V
3.9
2.5
1.2
1.5
3.9
2.5
1.2
1.5
V
mA
4
Electrical Characteristics
Symbol
Parameter
Test Condition
Min
SG1846
SG2846
Typ Max Min
SG3846
Typ
Max
Units
Error AMP Section
EA
VOS
EA
IIB
EA
IOS
EA
CM
EA
AV
EA
UGB
EA
CMRR
EA
PSRR
EA
SNK
EA
SRC
EA
VOH
EA
VOL
Input Offset Voltage
Input Bias Current
Input Offset Current
Common Mode Range
V
IN
= 8V to 40V
0
80
0.7
75
80
2
-0.4
4.3
105
1.0
100
105
6
-0.5
4.6
0.7
1
0.5
-0.6
40
5
-1
250
V
IN
-
2V
0
80
0.7
75
80
2
-0.4
4.3
105
1.0
100
105
6
-0.5
4.6
0.7
1
0.5
-0.6
40
10
-2
250
V
IN
-2V
mV
µA
nA
V
dB
MHz
dB
dB
mA
mA
V
V
Open Loop Voltage Gain V
O
= 1.2V to 3V, V
CM
= 2V
Unity Gain Bandwidth
CMRR
PSRR
Output Sink Current
Output Source Current
High Level Output
Voltage
1
T
J
= 25°C
V
CM
= 0V to 38V, V
IN
= 40V
V
IN
= 8V to 40V
V
ID
= - 15mV to -5V, V
PIN 7
=
1.2V
V
ID
= 15mV to 5V, V
PIN 7
=
2.5V
R
L
= 15kΩ (Pin 7)
Low Level Output Voltage R
L
= 15kΩ (Pin 7)
Current Sense Amplifier Section
CS
AV
Amplifier Gain
2 &3
3
V
PIN 3
= 0V, Pin 1 Open
2.5
1.1
2.75
1.2
5
3.0
2.5
1.1
2.75
1.2
5
3.0
V
V
Maximum Differential
2
Input Signal (V
PIN 4
- V
PIN
Pin 1 Open R
L
= 15kΩ (Pin 7)
3
)
Input Offset Voltage
CS
CMRR
CS
PSRR
CS
IIB
CSI
OC
CS
CM
CMRR
PSRR
Input Bias Current
2
2
2
V
PIN 1
= 0.5V, Pin 7 Open
V
CM
= 1V to 12V
V
IN
= 8V to 40V
V
PIN 1
= 0.5V, Pin 7 Open
V
PIN 1
= 0.5V, Pin 7 Open
0
T
J
= 25°C
60
60
25
60
60
-10
1
V
IN
-
3
0
25
mV
dB
dB
83
84
-2.5
0.08
83
84
-2.5
0.08
-10
1
V
IN
-3
200
500
µA
µA
V
ns
Input Offset Current
Input Common Mode
Range
Delay to Outputs
1
200
500
Current Limit Adjust Section
Current Limit Offset
2
Voltage
CL
IIB
Input Bias Current
V
PIN 3
= 0, V
PIN 4
= 0V, Pin 7
Open
V
PIN 5
= V
REF
, V
PIN 6
= 0V
0.45
0.5
-10
0.55 0.45
-30
0.5
-10
0.55
-30
V
µA
5
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