Microsemi Corporation SG1844Y, SG1844Y-883B, SG1844Y-DESC, SG1845F-DESC, SG1845J Datasheet

LIN DOC #: 1844

SG1844/SG1845 Series

C

URRENT MODE

PWM C

ONTROLLER

T HE I NFINITE P OWER OF I NNOVATION

DESCRIPTION KEY FEATURES

The SG1844/45 family of control ICs
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-by­pulse 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 SG1844/45 has under­voltage 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.

Both operate up to a maximum duty
cycle range of zero to <50% due to an
internal toggle flip-flop which blanks the
output off every other clock cycle.

The SG1844/45 is specified for
operation over the full military ambient
temperature range of -55°C to 125°C.
The SG2844/45 is specified for the
industrial range of -25°C to 85°C, and
the SG3844/45 is designed for the
commercial range of 0°C to 70°C.

PRODUCT HIGHLIGHT

TYPICAL APPLICATION OF SG3844 IN A FLYBACK CONVERTER

P RODUCTION DATA SHEET

■ OPTIMIZED FOR OFF-LINE CONTROL

■ LOW START-UP CURRENT (<1mA)

■ AUTOMATIC FEED FORWARD

COMPENSATION

■ TRIMMED OSCILLATOR DISCHARGE

CURRENT

■ PULSE-BY-PULSE CURRENT LIMITING

■ ENHANCED LOAD RESPONSE

CHARACTERISTICS

■ UNDER-VOLTAGE LOCKOUT WITH 6V

HYSTERESIS (SG1844 only)

■ DOUBLE PULSE SUPPRESSION

■ HIGH-CURRENT TOTEM-POLE OUTPUT

■ INTERNALLY TRIMMED BANDGAP

REFERENCE

■ 500kHz OPERATION

■ UNDERVOLTAGE LOCKOUT

SG1844 - 16 volts
SG1845 - 8.4 volts

■ LOW SHOOT-THROUGH CURRENT <75mA

OVER TEMPERATURE

(°C)

T

A

0 to 70

-25 to 85

-55 to 125

MIL-STD/883

DESC

R

AC

INPUT

I

V

CC

SG3844

ST

ST

■ AVAILABLE TO MIL-STD-883B

■

LINFINITY LEVEL "S" PROCESSING AVAILABLE

PACKAGE ORDER INFORMATION

HIGH RELIABILITY FEATURES

Plastic DIP

M

8-pin

SG3844M SG3844N SG3844DM SG3844D SG3844Y SG3844J — —

SG3845M SG3845N SG3845DM SG3845D SG3845Y SG3845J — —

SG2844M SG2844N SG2844DM SG2844D SG2844Y SG2844J — —

SG2845M SG2845N SG2845DM SG2845D SG2845Y SG2845J — —

— — — — SG1844Y SG1844J — SG1844L

— — — — SG1845Y SG1845J — SG1845L

— — — — SG1844Y/883B SG1844J/883B — SG1844L/883B

— — — — SG1845Y/883B SG1845J/883B — SG1845L/883B

— — — — SG1844Y/DESC SG1844J/DESC SG1844F/DESC SG1844L/DESC

Plastic DIP

N

14-pin

Plastic SOIC

DM

8-pin

— — SG1845Y/DESC SG1845J/DESC SG1845F/DESC SG1845L/DESC

Note: All surface-mount packages are available in Tape & Reel.

Plastic SOIC

D

14-pin

Ceramic DIP

Y

8-pin

Ceramic DIP

J

14-pin

Cer. Flatpack

F

10-pin

L

Ceramic LCC
20-pin

Copyright © 2000
Rev. 1.4 4/00

FOR FURTHER INFORMATION CALL [phone]

11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841

1

PRODUCT DATABOOK 1996/1997

SG1844/SG1845 Series

C

URRENT-MODE

P RODUCTION DATA SHEET

PWM C

ONTROLLER

ABSOLUTE MAXIMUM RATINGS (Notes 1 & 2)

Supply Voltage (ICC < 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

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.

THERMAL DATA

M PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

N PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

DM PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

D PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

Y PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

J PACKAGE:

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

F PACKAGE:

THERMAL RESISTANCE-JUNCTION TO CASE,

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

L PACKAGE:

THERMAL RESISTANCE-JUNCTION TO CASE,

THERMAL RESISTANCE-JUNCTION TO AMBIENT,

Junction Temperature Calculation: TJ = TA + (PD x θJA).
The θJA numbers are guidelines for the thermal performance of the device/pc-board
system. All of the above assume no ambient airflow.

θθ

θ

θθ

JA

θθ

θ

θθ

JA

θθ

θ

θθ

JA

θθ

θ

θθ

JA

θθ

θ

θθ

JA

θθ

θ

θθ

JA

θθ

θ

θθ

JC

θθ

θ

θθ

JA

θθ

θ

θθ

JC

θθ

θ

θθ

JA

95°C/W

65°C/W

165°C/W

120°C/W

130°C/W

80°C/W

80°C/W

145°C/W

35°C/W

120°C/W

1. COM

2. V

FB

3. I

SENSE

4. RT/C

T

5. OWER GND

32

4

5

6

7

8

91110

PACKAGE PIN OUTS

1 8

COM

27

V

FB

36

I

SENSE

45

RT/C

T

M & Y PACKAGE

(Top View)

SENSE

V

FB

T

1 8

27

36

45

COM

I

RT/C

DM PACKAGE

(Top View)

N.C.

V
N.C.
I

SENSE

N.C.

FB

T

1 14

213

3 12

411

510

69

78

COM

RT/C

D PACKAGE

(Top View)

1 14

COM

213

N.C.

3 12

V

FB

411

N.C.

510

I

SENSE

69

N.C.

78

RT/C

T

J & N PACKAGE

(Top View)

1 10
29
38
47
56

F PACKAGE

(Top View)

12019

12 13

L PACKAGE

(Top View)

V

REF

V

CC

OUT UT
GND

V

REF

V

CC

OUT UT
GND

V

REF

N.C.
V

CC

V

C

OUT UT
GND

WR GND

V

REF

N.C.
V

CC

V

C

OUT UT
GROUND

OWER GND

1. N.C.

2. N.C.

3. COM .

18

4. N.C.

17

5. V

16

15

14

FB

6. N.C.

7. I

SENSE

8. RT/C

9. N.C.

10. N.C.

T

10.V

REF

9. V

CC

8. V

C

7. OUT UT

6. GND

11. N.C.

12. WR GND

13. GND

14. N.C.

15. OUT UT

16. N.C.

17. V

C

18. V

CC

19. N.C.

20. V

REF

2

Copyright © 2000

Rev. 1.4 4/00

PRODUCT DATABOOK 1996/1997

SG1844/SG1845 Series

C

URRENT-MODE

P RODUCTION DATA SHEET

RECOMMENDED OPERATING CONDITIONS (Note 3)

PWM C

ONTROLLER

Parameter

Symbol

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 R
Oscillator Timing Capacitor C

T

T

Recommended Operating Conditions

Min. Typ. Max.

Units

30 V
±1 A

200 mA

02.6V
5mA

0.1 500 kHz

0.52 150 kΩ

0.1 1.0 µF

Operating Ambient Temperature Range:

SG1844/45
SG2844/45
SG3844/45

-55 125 °C

-25 85 °C
070°C

Note 3. Range over which the device is functional.

ELECTRICAL CHARACTERISTICS

(Unless otherwise specified, these specifications apply over the operating ambient temperatures for SG1844/SG1845 with -55°C ≤ TA ≤ 125°C, SG2844/
SG2845 with -25°C ≤ TA ≤ 85°C, SG3844/SG3845 with 0°C ≤ TA ≤ 70°C, VCC = 15V (Note 7), RT = 10kΩ, and CT = 3.3nF. Low duty cycle pulse testing
techniques are used which maintains junction and case temperatures equal to the ambient temperature.)

Parameter

Symbol

Test Conditions

SG1844/45

SG2844/45

Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.

SG3844/45

Units

Reference Section

Output Voltage TJ = 25°C, IO = 1mA
Line Regulation 12 ≤ VIN ≤ 25V
Load Regulation 1 ≤ IO ≤ 20mA
Temperature Stability (Note 4)
Total Output Variation (Note 4) Line, Load, Temp.
Output Noise Voltage (Note 4) VN10Hz ≤ f ≤ 10kHz, TJ = 25°C
Long Term Stability (Note 4) TA = 125°C, 1000hrs
Output Short Circuit

4.95 5.00 5.05 4.95 5.00 5.05 4.90 5.00 5.10 V
620 620 620 mV
625 625 625 mV

0.2 0.4 0.2 0.4 0.2 0.4 mV/°C

4.90 5.10 4.90 5.10 4.82 5.18 V

50 50 50 µV

525 525 525 mV

-30 -100 -180 -30 -100 -180 -30 -100 -180 mA

Oscillator Section

Initial Accuracy (Note 8) TJ = 25°C
Voltage Stability 12V ≤ VCC ≤ 25V
Temperature Stability (Note 4) T
Amplitude V

≤ TA ≤ T

MIN

(Peak to Peak)

RT/CT

MAX

Discharge Current TJ = 25°C

T

≤ TA ≤ T

MIN

MAX

47 52 57 47 52 57 47 52 57 kHz

.021 0.21 0.21 %

555%

1.7 1.7 1.7 V

7.8 8.3 9.1 7.5 8.4 9.3 7.5 8.4 9.3 mA

6.8 9.3 7.2 9.5 7.2 9.5 mA

Error Amp Section

Input Voltage V
Input Bias Current
Open Loop Gain A

VOL

Unity Gain Bandwidth (Note 4) TJ = 25°C
Power Supply Rejection Ratio PSRR 12 ≤ VCC ≤ 25V
Output Sink Current V
Output Source Current V
V

High V

OUT

V

Low V

OUT

= 2.5V

COMP

2 ≤ VO ≤ 4V

= 2.7V, V

VFB

= 2.3V, V

VFB

= 2.3V, RL = 15K to gnd

VFB

= 2.7V, RL = 15K to V

VFB

COMP

COMP

= 1.1V
= 5V

2.45 2.50 2.55 2.45 2.50 2.55 2.42 2.50 2.58 V

-0.3 -1 -0.3 1 -0.3 -2 µA

65 90 65 90 65 90 dB

0.7 1 0.7 1 0.7 1 MHz
60 70 60 70 60 70 dB

26 26 26 mA

-0.5 -0.8 -0.5 -0.8 -0.5 -0.8 mA
56 56 56 V

REF

0.7 1.1 0.7 1.1 0.7 1.1 V

(Electrical Characteristics continue next page.)

Copyright © 2000
Rev. 1.4 4/00

3

PRODUCT DATABOOK 1996/1997

SG1844/SG1845 Series

C

URRENT-MODE

P RODUCTION DATA SHEET

ELECTRICAL CHARACTERISTICS (Cont'd.)

PWM C

ONTROLLER

Parameter

Symbol

Test Conditions

Current Sense Section

Gain (Notes 5 & 6)
Maximum Input Signal (Note 5) V
Power Supply Rejection Ratio (Note 5) PSRR 12 ≤ V
Input Bias Current
Delay to Output (Note 4)

COMP

= 5V

CC

≤ 25V

Output Section

Output Low Level I

Output High Level I

Rise Time (Note 4) T J = 25°C, CL = 1nF
Fall Time (Note 4) TJ = 25°C, CL = 1nF

= 20mA

SINK

I

= 200mA

SINK

SOURCE

I

SOURCE

= 20mA
= 200mA

Under-Voltage Lockout Section

Start Threshold 1844

1845

Min. Operation Voltage After Turn-On 1844

1845

PWM Section

Maximum Duty Cycle
Minimum Duty Cycle

Power Consumption Section

Start-Up Current
Operating Supply Current VFB = V
VCC Zener Voltage ICC = 25mA

Notes: 4. These parameters, although guaranteed, are not 100% tested in

production.

5. Parameter measured at trip point of latch with V

ISENSE

VFB

= 0V

= 0.

SG1844/45

SG2844/45

Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.

2.85 3 3.15 2.85 3 3.15 2.85 3 3.15 V/V

0.9 1 1.1 0.9 1 1.1 0.9 1 1.1 V
70 70 70 dB

-2 -10 -2 -10 -2 -10 µA

150 300 150 300 150 300 ns

0.1 0.4 0.1 0.4 0.1 0.4 V

1.5 2.2 1.5 2.2 1.5 2.2 V
13 13.5 13 13.5 13 13.5 V
12 13.5 12 13.5 12 13.5 V

50 150 50 150 50 150 ns
50 150 50 150 50 150 ns

15 16 17 15 16 17 14.5 16 17.5 V

7.8 8.4 9.0 7.8 8.4 9.0 7.8 8.4 9.0 V
9 10 11 9 10 11 8.5 10 11.5 V

7.0 7.6 8.3 7.0 7.6 8.2 7.0 7.6 8.2 V

46 48 50 46 48 50 46 48 50 %

000%

0.5 1 0.5 1 0.5 1 mA
11 17 11 17 11 17 mA
34 34 34 V

∆ V

6. Gain defined as: A = ; 0 ≤ V

7. Adjust VCC above the start threshold before setting at 15V.

8. Output frequency equals one half of oscillator frequency.

∆ V

COMP

ISENSE

SG3844/45

≤ 0.8V.

ISENSE

Units

4

Copyright © 2000

Rev. 1.4 4/00