NSC LM1085IS-5.0, LM1085IS-3.3, LM1085IT-ADJ, LM1085IT-3.3, LM1085IT-12 Datasheet

July 1999

LM1085

3A Low Dropout Positive Regulators

General Description

The LM1085 is a series of low dropout positive voltage regulators with a maximum dropout of 1.5V at 3A of load current. It has the same pin-out as National Semiconductor's industry standard LM317.

The LM1085 is available in an adjustable version, which can set the output voltage with only two external resistors. It is also available in three fixed voltages: 3.3V, 5.0V and 12.0V. The fixed versions integrate the adjust resistors.

The LM1085 circuit includes a zener trimmed bandgap reference, current limiting and thermal shutdown.

The LM1085 series is available in TO-220 and TO-263 packages.

Features

nAvailable in 3.3V, 5.0V, 12V and Adjustable Versions

nCurrent Limiting and Thermal Protection

n Output Current			3A
n	Line Regulation	0.015%	(typical)
n	Load Regulation	0.1%	(typical)

Applications

nHigh Efficiency Linear Regulators

nBattery Charger

nPost Regulation for Switching Supplies

nConstant Current Regulator

nMicroprocessor Supply

Connection Diagrams

TO-220

TO-263

DS100947-2

Top View

DS100947-4

Top View

Basic Functional Diagram, Adjustable Version

DS100947-65

Regulators Positive Dropout Low 3A LM1085

© 1999 National Semiconductor Corporation

DS100947

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Ordering Information

Package	Temperature Range	Part Number	Transport Media	NSC Drawing
3-lead TO-263	−40ÊC to +125ÊC	LM1085IS-ADJ	Rails
		LM1085ISX-ADJ	Tape and Reel
		LM1085IS-12	Rails	TS3B
		LM1085ISX-12	Tape and Reel
		LM1085IS-3.3	Rails
		LM1085ISX-3.3	Tape and Reel
		LM1085IS-5.0	Rails
		LM1085ISX-5.0	Tape and Reel
3-lead TO-220	−40ÊC to + 125ÊC	LM1085IT-ADJ	Rails
		LM1085IT-12	Rails	T03B
		LM1085IT-3.3	Rails
		LM1085IT-5.0	Rails

Simplified Schematic

DS100947-34

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Absolute Maximum Ratings (Note 1)

If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.

Maximum Input to Output Voltage Differential

LM1085-ADJ	29V
LM1085-12	18V
LM1085-3.3	27V
LM1085-5.0	25V
Power Dissipation (Note 2)	Internally Limited

Junction Temperature (TJ)(Note 3)	150ÊC
Storage Temperature Range	-65ÊC to 150ÊC
Lead Temperature	260ÊC, to 10 sec
ESD Tolerance (Note 4)	2000V

Operating Ratings (Note 1)

Junction Temperature Range (TJ) (Note 3)

Control Section	−40ÊC to 125ÊC
Output Section	−40ÊC to 150ÊC

Electrical Characteristics

Typicals and limits appearing in normal type apply for TJ = 25ÊC. Limits appearing in Boldface type apply over the entire junction temperature range for operation.

Symbol	Parameter	Conditions	Min	Typ	Max	Units
			(Note	(Note	(Note
			6)	5)	6)
VREF	Reference	LM1085-ADJ
	Voltage	IOUT = 10mA, VIN−V OUT = 3V	1.238	1.250	1.262	V
		10mA ≤IOUT ≤ IFULL LOAD,1.5V ≤ (VIN−V OUT) ≤ 15V	1.225	1.250	1.270	V
		(Note 7)
VOUT	Output Voltage	LM1085-3.3	3.270	3.300	3.330	V
	(Note 7)	IOUT = 0mA, VIN = 5V
			3.235	3.300	3.365	V
		0 ≤ IOUT ≤IFULL LOAD, 4.8V≤ VIN ≤15V
		LM1085-5.0	4.950	5.000	5.050	V
		IOUT = 0mA, VIN = 8V
			4.900	5.000	5.100	V
		0 ≤ IOUT ≤ IFULL LOAD, 6.5V ≤ VIN ≤ 20V
		LM1085-12	11.880	12.000	12.120	V
		IOUT = 0mA, VIN = 15V
			11.760	12.000	12.240	V
		0 ≤ IOUT ≤ IFULL LOAD, 13.5V ≤ VIN ≤ 25V
VOUT	Line Regulation	LM1085-ADJ		0.015	0.2	%
	(Note 8)	IOUT =10mA, 1.5V≤ (VIN-VOUT) ≤ 15V		0.035	0.2	%
		LM1085-3.3		0.5	6	mV
		IOUT = 0mA, 4.8V ≤ VIN ≤ 15V		1.0	6	mV
		LM1085-5.0		0.5	10	mV
		IOUT = 0mA, 6.5V ≤ VIN ≤ 20V		1.0	10	mV
		LM1085-12		1.0	25	mV
		I OUT =0mA, 13.5V ≤ VIN ≤ 25V		2.0	25	mV
VOUT	Load Regulation	LM1085-ADJ		0.1	0.3	%
	(Note 8)	(VIN-V OUT) = 3V, 10mA ≤ IOUT ≤ IFULL LOAD		0.2	0.4	%
		LM1085-3.3		3	15	mV
		VIN = 5V, 0 ≤ IOUT ≤ IFULL LOAD		7	20	mV
		LM1085-5.0		5	20	mV
		VIN = 8V, 0 ≤ IOUT ≤ IFULL LOAD		10	35	mV
		LM1085-12		12	36	mV
		VIN = 15V, 0 ≤ IOUT ≤ IFULL LOAD		24	72	mV
	Dropout Voltage	LM1085-3.3/5/12/ADJ
	(Note 9)	VREF = 1%, IOUT = 3A		1.3	1.5	V

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Electrical Characteristics (Continued)

Typicals and limits appearing in normal type apply for TJ = 25ÊC. Limits appearing in Boldface type apply over the entire junction temperature range for operation.

Symbol	Parameter	Conditions	Min	Typ	Max	Units
			(Note	(Note	(Note
			6)	5)	6)
ILIMIT	Current Limit	LM1085-ADJ
		VIN−V OUT = 5V	3.2	5.5		A
		VIN−V OUT = 25V	0.2	0.5		A
		LM1085-3.3
		VIN = 8V	3.2	5.5		A
		LM1085-5.0
		VIN = 10V	3.2	5.5		A
		LM1085-12
		VIN = 17V	3.2	5.5		A
	Minimum Load	LM1085-ADJ
	Current (Note 10)	VIN −V OUT = 25V		5.0	10.0	mA
	Quiescent	LM1085-3.3
	Current	VIN ≤ 18V		5.0	10.0	mA
		LM1085-5.0
		VIN ≤ 20V		5.0	10.0	mA
		LM1085-12
		VIN ≤ 25V		5.0	10.0	mA
	Thermal	TA = 25ÊC, 30ms Pulse		.004	0.02	%/W
	Regulation
	Ripple Rejection	fRIPPLE = 120Hz, COUT = 25µF Tantalum, IOUT =
		3A
		LM1085-ADJ, CADJ = 25µF, (VIN−V O) = 3V	60	75		dB
		LM1085-3.3, VIN = 6.3V	60	72		dB
		LM1085-5.0, VIN= 8V	60	68		dB
		LM1085-12 VIN = 15V	54	60		dB
	Adjust Pin	LM1085		55	120	µA
	Current
	Adjust Pin	10mA ≤ IOUT ≤ IFULL LOAD, 1.5V ≤ VIN−V OUT ≤ 25V
	Current Change			0.2	5	µA
	Temperature			0.5		%
	Stability
	Long Term	TA=125ÊC, 1000Hrs
	Stability			0.3	1.0	%
	RMS Output	10Hz ≤ f≤ 10kHz		0.003		%
	Noise
	(% of VOUT)
	Thermal	3-Lead TO-263: Control Section/Output Section			0.7/3.0	ÊC/W
	Resistance	3-Lead TO-220: Control Section/Output Section			0.7/3.0	ÊC/W
	Junction-to-Case

Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is intended to be functional, but specific performance is not guaranteed. For guaranteed specifications and the test conditions, see the Electrical Characteristics.

Note 2: Power dissipation is kept in a safe range by current limiting circuitry. Refer to Overload Recovery in Application Notes.

Note 3: The maximum power dissipation is a function of TJ(max) , θJA, and TA. The maximum allowable power dissipation at any ambient temperature is PD = (TJ(max)±T A)/θJA. All numbers apply for packages soldered directly into a PC board. Refer to Thermal Considerations in the Application Notes.

Note 4: For testing purposes, ESD was applied using human body model, 1.5kΩ in series with 100pF.

Note 5: Typical Values represent the most likely parametric norm.

Note 6: All limits are guaranteed by testing or statistical analysis.

Note 7: IFULL LOAD is defined in the current limit curves. The IFULL LOAD Curve defines the current limit as a function of input-to-output voltage. Note that 30W power dissipation for the LM1085 is only achievable over a limited range of input-to-output voltage.

Note 8: Load and line regulation are measured at constant junction temperature, and are guaranteed up to the maximum power dissipation of 30W. Power dissipation is determined by the input/output differential and the output current. Guaranteed maximum power dissipation will not be available over the full input/output range.

Note 9: Dropout voltage is specified over the full output current range of the device.

Note 10: The minimum output current required to maintain regulation.

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