CURRENT MODE PWM CONTROLLER
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 capability
••
••
•Shutdown capability
••
••
•500KHz operation
HIGH RELIABILITY FEATURES - SG1846
♦♦
♦♦
♦Available to MIL-STD - 883
♦♦
♦♦
♦Radiation data available
♦♦
♦♦
♦LMI level "S" processing available
DESCRIPTION
The SG1846 family of control ICs provides all of the necessary
features to implement fixed frequency, current mode control
schemes while maintaining a minimum external parts count. The
superior performance of this technique can be measured in im-
proved line regulation, enhanced load response characteristics,
and a simpler, easier-to-design control loop. Topological advan-
tages 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 sup-
pression, deadtime adjust capability, and a ±1% trimmed bandgap
reference.
BLOCK DIAGRAM
SG1846/SG2846/SG3846
Rev 1.1a 3.21.2005 Microsemi Inc.
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
1(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
2(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
ABSOLUTE MAXIMUM RATINGS (Note 1 and 2) Sync Output Current ...........................................................5mA
Error Amplifier Output Current ............................................5mA
Oscillator Charging current (Pin 9) .....................................5mA
Operating Junction Temperature
Hermetic (J, L, F Packages)........................................ 150°C
Plastic (N, DW Package)............................................. 150°C
Storage Temperature Range ............................ -65°C to 150°C
Lead Temperature (Soldering, 10 Seconds) .................. 300°C
Supply Voltage (+VIN).......................................................... 40V
Collector Supply Voltage(VC) .............................................. 40V
Analog Inputs (Pins 3, 4, 5, 6, & 16) ......................-0.3V to +VIN
Logic Input ...........................................................-0.3V to 5.5V
Soure/Sink Load current (continuous) .......................... 200mA
Source/Sink Load Current (peak, 200ns) ...................... 500mA
Reference Load Current .................................................. 30mA
Soft Start Sink Current ..................................................... 50mA
Note 1. Values beyond which damage may occur.
Note 2. Pin numbers refer to ceramic J package.
THERMAL DATA
J Package:
Thermal Resistance-Junction to Case , θJC.................. 30°C/W
Thermal Resistance-Junction to Ambient, θJA .............. 80°C/W
N Package:
Thermal Resistance-Junction to Case , θJC.................. 40°C/W
Thermal Resistance-Junction to Ambient, θJA ............. 65°C/W
DW Package:
Thermal Resistance-Junction to Case , θJC................... 40°C/W
Thermal Resistance-Junction to Ambient, θJA ............. 95°C/W
F Package:
Thermal Resistance-Junction to Case , θJC.................. 70°C/W
Thermal Resistance-Junction to Ambient, θJA ........... 115°C/W
L Package:
Thermal Resistance-Junction to Case , θJC.................. 35°C/W
Thermal Resistance-Junction to Ambient, θJA ........... 120°C/W
Note A. Junction Temperature Calculation: TJ = TA + (PD x θJA).
Note B. The above numbers for θJC are maximums for the limiting
thermal resistance of the package in a standard mount-
ing configuration. The θJA numbers are meant to be
guidelines for the thermal performance of the device/pc-
board system. All of the above assume no ambient
airflow.
5.10
5
3
0.4
100
5
-45
Reference Section TJ = 25°C, IO = 1mA
VIN = 8V to 40V
IL = 1mA to 10mA
Line, Load and Temperature
10Hz ≤ f ≤ 10KHz. TJ = 25°C
TJ = 125°C, 1000Hrs.
VREF = 0V
5.05
5.00
-10
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)
Short Circuit Output Current
Oscillator Timing Resistor (RT)........................... 2KΩ to 100KΩ
Oscillator Timing Capacitor (CT) .................... 1000 pF to 0.1µF
Operating Ambient Temperature Range
SG1846 ...........................................................-55°C to 125°C
SG2846 .............................................................-25°C to 85°C
SG3846 ................................................................0°C to 70°C
Note 3. Range over which the device is functional.
RECOMMENDED OPERATING CONDITIONS (Note 3)
Supply Voltage Range ............................................... 8V to 40V
Collector Supply Voltage Range............................. 4.5V to 40V
Source/Sink Output Current (continuous)...................... 100mA
Source/Sink Output Current (peak 200ns)....................200mA
Reference Load Current ........................................... 0 to 10mA
Oscillator Frequency Range ........................... 1KHz to 500KHz
ELECTRICAL CHARACTERISTICS
(Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG1846/SG1847 with -55°C ≤ TA ≤ 125°C, SG2846
with -25°C ≤ TA ≤ 85°C, SG3846 with 0°C ≤ TA ≤ 70°C, +VIN = 15V. Low duty cycle pulse testing techniques are used which maintains junction and
case temperatures equal to the ambient temperature.)
Units
SG1846
SG2846 SG3846
Parameter Test Conditions
5.15
20
15
5.20
5.00
4.95
-10
Min. Typ. Max.Min. Typ. Max.
5.10
5
3
0.4
100
5
-45
5.20
20
15
5.25
V
mV
mV
mV/°C
V
µV
mV
mA
RoHS Peak Package Solder Reflow Temp. (40 sec. max. exp.) .. 260° (+0, -5)
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
3(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
Collector Emitter Voltage
Collector Leakage Current
Output Low Level
Output High Level
Rise Time (Note 4)
Fall Time (Note 4)
Threshold Voltage
Input Voltage Range
Minimum Latching Current
(IPIN 1) (Note 7)
Maximum Non-Latching Current
(IPIN 1) (Note 8)
Delay to Outputs (Note 4) TJ = 25°C
250
0
3.0
350
1.5
1.5
300
400
VIN
0.8
600
250
0
3.0
350
1.5
1.5
300
400
VIN
0.8
600
mV
V
mA
mA
ns
Output Section
VC = 40V
ISINK = 20mA
ISINK = 100mA
ISOURCE = 20mA
ISOURCE = 100mA
CL = 1nF, TJ = 25°C
CL = 1nF, TJ = 25°C
40
13
12
0.1
0.4
13.5
13.5
50
50
200
0.4
2.1
300
300
40
13
12
0.1
0.4
13.5
13.5
50
50
200
0.4
2.1
300
300
V
µA
V
V
V
V
ns
ns
Amplifier Gain (Notes 5 & 6)
Maximum Differential (Note 6)
Input Signal (VPIN 4 - VPIN 3)(Note 5)
Input Offset Voltage (Note 5)
CMRR
PSRR
Input Bias Current (Note 5)
Input Offset Current (Note 5)
Input Common Mode Range
Delay to Outputs (Note 4)
2.5
1.1
60
60
0
2.75
1.2
5
83
84
-2.5
0.08
200
3.0
25
-10
1
VIN -3
500
2.5
1.1
60
60
0
2.75
1.2
5
83
84
-2.5
0.08
200
3.0
25
-10
1
VIN -3
500
Input Offset Voltage
Input Bias Current
Input Offset Current
Common Mode Range
Open Loop Voltage Gain
Unity Gain Bandwidth (Note 4)
CMRR
PSRR
Output Sink Current
Output Source Current
High Level Output Voltage
Low Level Output Voltage
VIN = 8V to 40V
VO = 1.2V to 3V, VCM = 2V
TJ = 25°C
VCM = 0V to 38V, VIN = 40V
VIN = 8V to 40V
VID = - 15mV to -5V, VPIN 7 = 1.2V
VID = 15mV to 5V, VPIN 7 = 2.5V
RL = 15KΩ (Pin 7)
RL = 15KΩ (Pin 7)
0
80
0.7
75
80
2
-0.4
4.3
0.5
-0.6
40
105
1.0
100
105
6
-0.5
4.6
0.7
5
-1
250
VIN-2V
1
0.5
-0.6
40
105
1.0
100
105
6
-0.5
4.6
0.7
10
-2
250
VIN-2V
1
Error Amp Section
ELECTRICAL CHARACTERISTICS (continued)
Min. Typ. Max. Min. Typ. Max.
SG1846
SG2846
Parameter Test Conditions Units
SG3846
39
3.9
3.9
Initial Accuracy
Voltage Stability
Temperature Stability (Note 4)
Sync Output High Level
Sync Output Low Level
Sync Input High Level
Sync Input Low Level
Sync Input Current
TJ = 25°C
VIN = 8V to 40V
Over Operating Range
Pin 8 = 0V
Pin 8 = 0V
Sync Voltage = 5.25V, Pin 8 = 0V
43
1
1
4.35
2.3
1.2
47
2
2.5
2.5
1.5
39
3.9
3.9
43
1
1
4.35
2.3
1.2
47
2
2.5
2.5
1.5
KHz
%
%
V
V
V
V
mA
Oscillator Section (Note 9)
mV
µA
nA
V
dB
MHz
dB
dB
mA
mA
V
V
0
80
0.7
75
80
2
-0.4
4.3
Current Sense Amplifier Section VPIN 3 = 0V, Pin 1 Open
Pin 1 Open RL = 15KΩ (Pin 7)
VPIN 1 = 0.5V, Pin 7 Open
VCM = 1V to 12V
VIN = 8V to 40V
VPIN 1 = 0.5V, Pin 7 Open
VPIN 1 = 0.5V, Pin 7 Open
TJ = 25°C
V
V
mV
dB
dB
µA
µA
V
ns
Current Limit Adjust Section
Current Limit Offset Voltage(Note 5)
Input Bias Current 0.55
-30 0.5
-10 0.55
-30
0.450.5
-10
0.45VPIN 3 = 0, VPIN 4 = 0V, Pin 7 Open
VPIN 5 = VREF, VPIN 6 = 0V
Shutdown Terminal Section
V
µA
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
4(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
ELECTRICAL CHARACTERISTICS (continued)
Max. Min. Typ. Max.Typ.
SG3846
Parameter Test Conditions Units
SG1846
SG2846
7.7
0.75 8.0 7.7
0.75 8.0 V
V
Note 4.These parameters although guaranteed over the recommended
operating conditions, are not tested in production.
Note 5.Parameter measured at trip point of latch with VPIN 5 = VREF ,
VPIN 6 = 0V.
Note 6.Amplifier gain defined as : G = ; VPIN 4 = 0V to 1.0V
Note 7.Current into Pin 1 guaranteed to latch circuit in shutdown state.
Note 8.Current into Pin 1 guaranteed not to latch circuit in shutdown
state.
Note 9.RT = 10KΩ, CT = 4.7nF
Min.
CHARACTERISTIC CURVES
FIGURE 1.
REFERENCE VOLTAGE VS. TEMPERATURE FIGURE 2.
VREF SHORT CIRCUIT CURRENT VS. TEMPERATURE FIGURE 3.
CURRENT SENSE THRESHOLD
VS. ERROR AMPLIFIER OUTPUT
FIGURE 4.
CURRENT SENSE GAIN VS. TEMPERATURE FIGURE 5.
OSCILLATOR VALLEY VOLTAGE VS. TEMPERATURE FIGURE 6.
OSCILLATOR PEAK VOLTAGE VS. TEMPERATURE
Under-Voltage Lockout Section
Start-Up Threshold
Threshold Hysteresis
Total Standby Current
Supply Current 17 21 17 21 mA
∆ VPIN 7
∆ VPIN 4
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
5(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
CHARACTERISTIC CURVES (continued)
FIGURE 9.
SHUTDOWN DELAY TO OUTPUT VS. TEMPERATURE
FIGURE 7.
MINIMUM SCR LATCH CURRENT FIGURE 8.
CURRENT SENSE DELAY VS. TEMPERATURE
FIGURE 10.
ERROR AMPLIFIER INPUT OFFSET VOLTAGE
VS. TEMPERATURE
FIGURE 12.
OUTPUT TRANSISTOR SATURATION VOLTAGE
VS. OUTPUT CURRENT (SINK TRANSISTOR)
FIGURE 11.
ERROR AMP SINK CURRENT VS. TEMPERATURE
FIGURE 14.
SYNC PULSEWIDTH VS. TEMPERATURE
FIGURE 13.
OUTPUT TRANSISTOR SATURATION VOLTAGE
VS. OUTPUT CURRENT (SOURCE TRANSISTOR)
FIGURE 15.
SYNC PULSEWIDTH VS. TEMPERATURE
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
6(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
CHARACTERISTIC CURVES (continued)
APPLICATION INFORMATION
FIGURE 19- OSCILLATOR FREQUENCY CURVES
FIGURE 20 - OSCILLATOR CIRCUIT
2.2
RTCT
Oscillator frequency is approximated by the formula: fT ≈
FIGURE 17.
OSCILLATOR FREQUENCY VS. TEMPERATURE FIGURE 18.
DUTY CYCLE VS. TEMPERATURE
FIGURE 16.
OSCILLATOR FREQUENCY VS. TEMPERATURE
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
7(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
APPLICATION INFORMATION (continued)
FIGURE 21 - ERROR AMP OUTPUT CONFIGURATION
(Error amplifier can source up to 0.5mA) FIGURE 22 - CURRENT SENSE AMPCONNECTIONS
A small RC filter may be required in some applications to reduce switch
transients. Differential input allows remote, noise free switching.
FIGURE 23 - SINGLE ENDED BOOST CONFIGURATION
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
8(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
APPLICATIONS INFORMATION (continued)
FIGURE 24 - BUCK CONVERTER WITH CURRENT SENSE WINDING
FIGURE 25 - PUSH/PULL CONVERTER WITH SLOPE COMPENSATION
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞
∞ ∞
∞ Garden Grove, CA 92841
9(714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
APPLICATIONS INFORMATION (continued)
VREF
R1< 0.8mA
If < 0.8mA the shutdown latch will commutate
when ISS < 0.8mA and a restart cycle will be initiated.
VREF
R1If > 3mA the device will latch off
until power is recycled.
VREF
R1
VREF
R1>3mA (LATCHED OFF)
FIGURE 29 - SHUTDOWN WITHOUT AUTO-RESTART (LATCHED)FIGURE 28 - SHUTDOWN WITH AUTO-RESTART
FIGURE 26 - PULSE BY PULSE CURRENT LIMITING
FIGURE 27 - SOFT START AND SHUTDOWN/RESTART FUNCTIONS
SG1846
Rev 1.1a
Copyright 1994 11861 Western Avenue ∞ ∞ ∞ ∞
∞ Garden Grove, CA 92841
10 (714) 898-8121 ∞∞
∞∞
∞ FAX: (714) 893-2570
CONNECTION DIAGRAMS & ORDERING INFORMATION (See Notes Below)
Ambient
Temperature Range
Part No. Connection Diagram
Package
16-PIN CERAMIC DIP
J - PACKAGE SG1846J/883B -55°C to 125°C
SG1846J/DESC -55°C to 125°C
SG1846J -55°C to 125°C
SG2846J -25°C to 85°C
SG3846J 0°C to 70°C
Note s: 1. Contact factory for JAN and DESC part availability.
2. All parts are viewed from the top.
3. Consult factory for product availability.
SHUTDOWN
+VIN
OUTPUT B
VC
GROUND
OUTPUT A
SYNC
RT
CT
COMPENSATION
(-) ERROR AMP
(+) ERROR AMP
(+) C.S.
(-) C.S.
VREF
C.L./SOFTSTART 2
3
4
5
6
7
8
1
11
14
15
16
9
12
10
13
16-PIN PLASTIC DIP
N - PACKAGE SG2846N -25°C to 85°C
SG3846N 0°C to 70°C
2
3
4
5
6
7
8
1
13
12
11
14
15
10
9
16
11.N.C.
12.RT
13.SYNC
14.OUTPUT A
15.GROUND
16.N.C.
17.VC
18.OUTPUT B
19.VIN
20.SHUTDOWN
CT
COMPENSATION
(-) ERROR AMP
(+) ERROR AMP
(+) C.S.
(-) C.S.
VREF
C.L./SOFTSTART SHUTDOWN
+VIN
OUTPUT B
VC
GROUND
OUTPUT A
SYNC
RT
2
3
4
5
6
7
8
1
13
12
11
14
15
10
9
16
CT
COMPENSATION
(-) ERROR AMP
(+) ERROR AMP
(+) C.S.
(-) C.S.
VREF
C.L./SOFTSTART SHUTDOWN
+VIN
OUTPUT B
VC
GROUND
OUTPUT A
SYNC
RT
4
5
6
7
8
321
911121310
14
15
16
17
18
20 19
1. N.C.
2. C.L./SOFTSTART
3. VREF
4. (-) C.S.
5. (+) C.S.
6. N.C.
7. (+) ERROR AMP
8. (-) ERROR AMP
9. COMPENSATION
10. CT
16-PIN WIDEBODY
PLASTIC S.O.I.C
DW - PACKAGE
SG2846DW -25°C to 85°C
SG3846DW 0°C to 70°C
16-PIN CERAMIC
FLAT PACK
F - PACKAGE (Note 3)
20-PIN CERAMIC
LEADLESS CHIP CARRIER
L - PACKAGE (Note 3)
SG1846L/883B -55°C to 125°C
SG1846L/DESC -55°C to 125°C
SG1846L -55°C to 125°C
SG1846F/DESC -55°C to 125°C
N Package: RoHS Compliant / Pb-free Transition DC: 0503
N Package: RoHS / Pb-free 100% Matte Tin Lead Finish
DW Package: RoHS Compliant / Pb-free Transition DC: 0516
DW Package: RoHS / Pb-free 100% Matte Tin Lead Finish
