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

		LIN D O C #: 1844
		SG1844/SG1845 Series
		C U R R E N T M O D E P W M C O N T R O L L E R
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		P R O D U C T I O N D A T A S H E E T

D E S C R I P T I O N

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-by- pulse 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.

	P R O D U C T H I G H L I G H T
TY P I C A L AP P L I C AT I O N O F SG3844 IN A FLY B A C K CO N V E R T E R
	RST
AC	IST
INPUT	VCC

K E Y F E AT U R E S

■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

HIGH RELIABILITY FEATURES

■AVAILABLE TO MIL-STD-883B

■LINFINITY LEVEL "S" PROCESSING AVAILABLE

SG3844

PA C K A G E O R D E R I N F O R M AT I O N

TA (°C)

M

Plastic DIP

N

Plastic DIP

DM

Plastic SOIC

D

Plastic SOIC

Y

Ceramic DIP

J

Ceramic DIP

F

Cer. Flatpack

L

Ceramic LCC

8-pin

14-pin

8-pin

14-pin

8-pin

14-pin

10-pin

20-pin

0 to 70

SG3844M

SG3844N

SG3844DM

SG3844D

SG3844Y

SG3844J

—

—

SG3845M

SG3845N

SG3845DM

SG3845D

SG3845Y

SG3845J

—

—

-25 to 85

SG2844M

SG2844N

SG2844DM

SG2844D

SG2844Y

SG2844J

—

—

SG2845M

SG2845N

SG2845DM

SG2845D

SG2845Y

SG2845J

—

—

-55 to 125

—

—

—

—

SG1844Y

SG1844J

—

SG1844L

—

—

—

—

SG1845Y

SG1845J

—

SG1845L

MIL-STD/883

—

—

—

—

SG1844Y/883B

SG1844J/883B

—

SG1844L/883B

—

—

—

—

SG1845Y/883B

SG1845J/883B

—

SG1845L/883B

DESC

—

—

—

—

SG1844Y/DESC

SG1844J/DESC

SG1844F/DESC

SG1844L/DESC

—

—

SG1845Y/DESC

SG1845J/DESC

SG1845F/DESC

SG1845L/DESC

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

F O R F U R T H E R I N F O R M AT I O N C A L L ( 7 1 4 ) 8 9 8 - 8 1 2 1

Copyright © 2000	11861 WESTERN AVENUE, GARDEN GROVE, CA. 92841	1
Rev. 1.4 4/00

P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7

SG1844/SG1845 Series

C U R R E N T - M O D E P W M C O N T R O L L E R

P R O D U C T I O N D A T A S H E E T

	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, θJA	95°C/W
N PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA	65°C/W
DM PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA	165°C/W
D PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA	120°C/W
Y PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA	130°C/W
J PACKAGE:
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA	80°C/W
F PACKAGE:
THERMAL RESISTANCE-JUNCTION TO CASE, θJC	80°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA	145°C/W
L PACKAGE:
THERMAL RESISTANCE-JUNCTION TO CASE, θJC	35°C/W
THERMAL RESISTANCE-JUNCTION TO AMBIENT, θJA	120°C/W

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.

PACKAGE PIN OUTS

COM		1	8		VREF
VFB		2	7		VCC
ISENSE		3	6		OUT UT
RT/CT		4	5		GND

M & Y PACKAGE

(Top View)

COM				1	8			VREF
VFB				2	7			VCC
ISENSE				3	6			OUT UT
RT/CT				4	5			GND

DM PACKAGE

(Top View)

COM				1	14			VREF
N.C.				2	13			N.C.
VFB				3	12			VCC
N.C.				4	11			VC
ISENSE				5	10			OUT UT
N.C.				6	9			GND
RT/CT				7	8			WR GND

D PACKAGE

(Top View)

			COM			1			14			VREF
				N.C.		2			13			N.C.
				VFB		3			12			VCC
				N.C.		4			11			VC
				ISENSE		5			10			OUT UT
				N.C.		6			9			GROUND
				RT/CT		7			8			OWER GND
				J & N PACKAGE
						(Top View)
1. COM															10.VREF
2. VFB							1		10
							2		9						9.	VCC
3. ISENSE							3		8						8.	VC
4. RT/CT							4		7						7.	OUT UT
							5		6
5. OWER GND															6. GND
					F PACKAGE
						(Top View)
3	2	1		20	19					1.		N.C.			11.		N.C.
										2.		N.C.			12.		WR GND
4								18		3.		COM .			13.		GND
5								17		4.		N.C.			14.		N.C.
										5.		VFB			15.		OUT UT
6								16
										6.		N.C.			16.		N.C.
7								15		7.		ISENSE			17.		VC
8								14
										8.		RT/CT			18.		VCC
										9.		N.C.			19.		N.C.
9	10	11		12	13						10. N.C.				20.		VREF

L PACKAGE

(Top View)

2		Copyright © 2000
		Rev. 1.4 4/00

P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7

SG1844/SG1845 Series

C U R R E N T - M O D E P W M C O N T R O L L E R

P R O D U C T I O N D A T A S H E E T

		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			(Note 3)
		Parameter		Symbol		Recommended Operating Conditions				Units
						Min.		Typ.	Max.
	Supply Voltage Range							30		V
	Output Current (Peak)							±1		A
	Output Current (Continuous)							200		mA
	Analog Inputs (Pin 2, Pin 3)					0			2.6	V
	Error Amp Output Sink Current							5		mA
	Oscillator Frequency Range					0.1			500	kHz
	Oscillator Timing Resistor			RT		0.52			150	kΩ
	Oscillator Timing Capacitor			CT		0.1			1.0	µF
	Operating Ambient Temperature Range:
		SG1844/45				-55			125	°C
		SG2844/45				-25			85	°C
		SG3844/45				0			70	°C

Note 3. Range over which the device is functional.

E L E C T R I C A L C H A R A C T E R I S T I C S

(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			SG3844/45			Units
				Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
Reference Section
Output Voltage			TJ = 25°C, IO = 1mA	4.95	5.00	5.05	4.95	5.00	5.05	4.90	5.00	5.10	V
Line Regulation			12 ≤ VIN ≤ 25V		6	20		6	20		6	20	mV
Load Regulation			1 ≤ IO ≤ 20mA		6	25		6	25		6	25	mV
Temperature Stability	(Note 4)				0.2	0.4		0.2	0.4		0.2	0.4	mV/°C
Total Output Variation (Note 4)			Line, Load, Temp.	4.90		5.10	4.90		5.10	4.82		5.18	V
Output Noise Voltage	(Note 4)	VN	10Hz ≤ f ≤ 10kHz, TJ = 25°C		50			50			50		µV
Long Term Stability (Note 4)			TA = 125°C, 1000hrs		5	25		5	25		5	25	mV
Output Short Circuit				-30	-100	-180	-30	-100	-180	-30	-100	-180	mA
Oscillator Section
Initial Accuracy (Note 8)			TJ = 25°C	47	52	57	47	52	57	47	52	57	kHz
Voltage Stability			12V ≤ VCC ≤ 25V		.02	1		0.2	1		0.2	1	%
Temperature Stability	(Note 4)		TMIN ≤ TA ≤ TMAX		5			5			5		%
Amplitude			VRT/CT (Peak to Peak)		1.7			1.7			1.7		V
Discharge Current			TJ = 25°C	7.8	8.3	9.1	7.5	8.4	9.3	7.5	8.4	9.3	mA
			TMIN ≤ TA ≤ TMAX	6.8		9.3	7.2		9.5	7.2		9.5	mA
Error Amp Section
Input Voltage			VCOMP = 2.5V	2.45	2.50	2.55	2.45	2.50	2.55	2.42	2.50	2.58	V
Input Bias Current					-0.3	-1		-0.3	1		-0.3	-2	µA
Open Loop Gain		AVOL	2 ≤ VO ≤ 4V	65	90		65	90		65	90		dB
Unity Gain Bandwidth	(Note 4)		TJ = 25°C	0.7	1		0.7	1		0.7	1		MHz
Power Supply Rejection Ratio		PSRR	12 ≤ VCC ≤ 25V	60	70		60	70		60	70		dB
Output Sink Current			VVFB = 2.7V, VCOMP = 1.1V	2	6		2	6		2	6		mA
Output Source Current			VVFB = 2.3V, VCOMP = 5V	-0.5	-0.8		-0.5	-0.8		-0.5	-0.8		mA
VOUT High			VVFB = 2.3V, RL = 15K to gnd	5	6		5	6		5	6		V
VOUT Low			VVFB = 2.7V, RL = 15K to VREF		0.7	1.1		0.7	1.1		0.7	1.1	V

( E l e c t r i c a l C h a r a c t e r i s t i c s c o n t i n u e n e x t p a g e . )

Copyright © 2000	3
Rev. 1.4 4/00

P R O D U C T D A T A B O O K 1 9 9 6 / 1 9 9 7

SG1844/SG1845 Series

C U R R E N T - M O D E P W M C O N T R O L L E R

P R O D U C T I O N D A T A S H E E T

	Parameter	Symbol	Test Conditions	SG1844/45			SG2844/45				SG3844/45			Units
				Min. Typ. Max. Min. Typ. Max. Min. Typ. Max.
	Current Sense Section
	Gain (Notes 5 & 6)			2.85	3	3.15	2.85	3	3.15		2.85	3	3.15	V/V
	Maximum Input Signal (Note 5)		VCOMP = 5V	0.9	1	1.1	0.9	1	1.1		0.9	1	1.1	V
	Power Supply Rejection Ratio (Note 5)	PSRR	12 ≤ VCC ≤ 25V		70			70				70		dB
	Input Bias Current				-2	-10		-2	-10			-2	-10	µA
	Delay to Output (Note 4)				150	300		150	300			150	300	ns
	Output Section
	Output Low Level		ISINK = 20mA		0.1	0.4		0.1	0.4			0.1	0.4	V
			ISINK = 200mA		1.5	2.2		1.5	2.2			1.5	2.2	V
	Output High Level		ISOURCE = 20mA	13	13.5		13	13.5			13	13.5		V
			ISOURCE = 200mA	12	13.5		12	13.5			12	13.5		V
	Rise Time (Note 4)		T J = 25°C, CL = 1nF		50	150		50	150			50	150	ns
	Fall Time (Note 4)		TJ = 25°C, CL = 1nF		50	150		50	150			50	150	ns
	Under-Voltage Lockout Section
	Start Threshold		1844	15	16	17	15	16	17		14.5	16	17.5	V
			1845	7.8	8.4	9.0	7.8	8.4	9.0		7.8	8.4	9.0	V
	Min. Operation Voltage After Turn-On		1844	9	10	11	9	10	11		8.5	10	11.5	V
			1845	7.0	7.6	8.3	7.0	7.6	8.2		7.0	7.6	8.2	V
	PWM Section
	Maximum Duty Cycle			46	48	50	46	48	50		46	48	50	%
	Minimum Duty Cycle					0			0				0	%
	Power Consumption Section
	Start-Up Current				0.5	1		0.5	1			0.5	1	mA
	Operating Supply Current		VFB = VISENSE = 0V		11	17		11	17			11	17	mA
	VCC Zener Voltage		ICC = 25mA		34			34				34		V
								∆ VCOMP			0 ≤ VISENSE ≤ 0.8V.
	Notes: 4. These parameters, although guaranteed, are not 100% tested in			6. Gain defined as: A =				∆ VISENSE		;
	production.
	E L E C T R I C A L C H A R A C T E R I S T I C S (Cont'd.)

	5. Parameter measured at trip point of latch with VVFB	= 0.	7.	Adjust VCC above the start threshold before setting at 15V.
			8.	Output frequency equals one half of oscillator frequency.

4		Copyright © 2000
		Rev. 1.4 4/00