Linear Technology LT338A, LT138A, LM338, LM138 Datasheet

FEATURES

■Guaranteed 1% Initial Tolerance

■Guaranteed 0.3% Load Regulation

■Guaranteed 5A Output Current

■100% Thermal Limit Burn-In

■12A Transient Output Current

APPLICATIOUS

■High Power Linear Regulator

■Battery Chargers

■Power Driver

■Constant-Current Regulator

LT138A/LT338A

LM138/LM338

5A Positive Adjustable

Voltage Regulator

DESCRIPTIOU

The LT®138A series of adjustable regulators provide 5A output current over an output voltage range of 1.2V to 32V. The internal voltage reference is trimmed to less than 1%, enabling a very tight output voltage. In addition to excellent line and load regulation, with full overload protection, the LT138A incorporates new current limiting circuitry allowing large transient load currents to be handled for short periods. Transient load currents of up to 12A can be supplied without limiting, eliminating the need for a large output capacitor.

The LT138A is an improved version of the popular LM138 with improved circuit design and advanced process techniques to provide superior performance and reliability.

The graph below shows the significant improvement in output voltage tolerance achieved by using the LT138A or LT338A.

, LTC and LT are registered trademarks of Linear Technology Corporation.

TYPICAL APPLICATIOU

		Parallel Regulators for Higher Current*
		LT338A	0.01Ω **	5V
	VIN	VIN	VOUT
				8A
		ADJ
		LT350A	0.016Ω **
		VIN
			VOUT
		ADJ	121Ω
			1%
			365Ω
			1%
			138/338 TA01

*THIS CIRCUIT WILL NOT WORK WITH LM VERSION DEVICES **CURRENT SHARING RESISTORS DEGRADE REGULATION TO 1%

OUTPUT VOLTAGE ERROR (%)

Output Voltage Error

12
11
10
9
							2% RESISTORS
8															LM338
7
							1% RESISTORS
6															LM338
5															LT338A
4
							2% RESISTORS
3
															LT338A
2								1% RESISTORS
1
0
							10								100
1

OUTPUT VOLTAGE (V)

138A/338A TA02

1

LT138A/LT338A

LM138/LM338

ABSOLUTE

WAXIWUW

RATIUGS (Note 1)

Power Dissipation ..............................	Internally Limited
Input-to-Output Voltage Differential ........................	35V
Operating Junction Temperature Range
LT138A/LM138 ...............................	– 55°C to 150°C
LT338A/LM338 ...................................	0°C to 125°C

Storage Temperature Range ................	– 65°C to 150°C
Lead Temperature (Soldering, 10 sec).................	300°C

PRECOUDITIOUIUG

100% Thermal Limit Burn-In

PACKAGE/ORDER IUFORWATIOU

BOTTOM VIEW

VIN

2

CASE

IS OUTPUT

1

ADJ

K PACKAGE

2-LEAD TO-3 METAL CAN

TJMAX = 150°C, θJA = 35°C/ W, θJC = 1°C/ W (LT138A/LT138) TJMAX = 125°C, θJA = 35°C/ W, θJC = 1°C/ W (LT338A/LT338)

ORDER

PART NUMBER

LT138AK

LT338AK

LM138K

LM338K

FRONT VIEW

3 VOUT

2 VIN

1 ADJ

P PACKAGE

3-LEAD PLASTIC TO-3P

TJMAX = 125°C, θJA = 45°C/ W

ORDER

PART NUMBER

LM338P

Consult factory for Industrial grade parts.

ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 2)

					LT138A			LM138
SYMBOL	PARAMETER	CONDITIONS		MIN	TYP	MAX	MIN	TYP	MAX	UNITS
VREF	Reference Voltage	IOUT = 10mA, TJ = 25°C		1.238	1.250	1.262				V
		3V ≤ (VIN – VOUT) ≤ 35V,	●	1.225	1.250	1.270	1.19	1.24	1.29	V
		10mA ≤ IOUT ≤ 5A, P ≤ 50W
VOUT	Line Regulation	3V ≤ (VIN – VOUT) ≤ 35V, (Note 3)			0.005	0.01		0.005	0.01	%/V
VIN			●		0.02	0.04		0.02	0.04	%/V
VOUT	Load Regulation	10mA ≤ IOUT ≤ 5A, (Note 3)
IOUT		VOUT ≤ 5V			5	15		5	15	mV
		VOUT ≥ 5V			0.1	0.3		0.1	0.3	%
		VOUT ≤ 5V	●		20	30		20	30	mV
		VOUT ≥ 5V	●		0.3	0.6		0.3	0.6	%
	Thermal Regulation	20ms Pulse			0.002	0.01		0.002	0.01	%/W
	Ripple Rejection	VOUT = 10V, f = 120Hz
		CADJ = 0µF	●		60			60		dB
		CADJ = 10µF	●	60	75		60	75		dB
IADJ	Adjust Pin Current		●		45	100		45	100	µA
IADJ	Adjust Pin Current Change	10mA ≤ IOUT ≤ 5A,	●		0.2	5		0.2	5	µA
		3V ≤ (VIN – VOUT) ≤ 35V
	Minimum Load Current	(VIN – VOUT) = 35V	●		3.5	5		3.5	5	mA
ISC	Current Limit	(VIN – VOUT) ≤ 10V		5	8		5	8		A
		DC	●
		0.5ms Peak	●	6	12		6	12		A
		(VIN – VOUT) = 30V, TJ = 25°C			1	2		1		A

2

LT138A/LT338A

LM138/LM338

ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 2)

						LT138A			LM138
SYMBOL		PARAMETER	CONDITIONS		MIN	TYP	MAX	MIN	TYP	MAX	UNITS
VOUT		Temperature Stability		●		1	2		1		%
Temp
VOUT		Long-Term Stability	TA = 125°C, 1000 Hours			0.3	1		0.3	1	%
Time
en		RMS Output Noise (% of VOUT)	10Hz ≤ f ≤ 10kHz			0.001			0.003		%
θJC		Thermal Resistance	K Package				1			1	°C/W
		Junction-to-Case

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C. (Note 2)

						LT338A			LM338
SYMBOL		PARAMETER	CONDITIONS		MIN	TYP	MAX	MIN	TYP	MAX	UNITS
VREF		Reference Voltage	IOUT = 10mA		1.238	1.250	1.262				V
			3V ≤ (VIN – VOUT) ≤ 35V,	●	1.225	1.250	1.270	1.19	1.24	1.29	V
			10mA ≤ IOUT ≤ 5A, P ≤ 50W
VOUT		Line Regulation	3V ≤ (VIN – VOUT) ≤ 35V, (Note 3)			0.005	0.01		0.005	0.03	%/V
VIN				●		0.02	0.04		0.02	0.06	%/V
VOUT		Load Regulation	10mA ≤ IOUT ≤ 5A, (Note 3)
IOUT			VOUT ≤ 5V			5	15		5	25	mV
			VOUT ≥ 5V			0.1	0.3		0.1	0.5	%
			VOUT ≤ 5V	●		20	30		20	50	mV
			VOUT ≥ 5V	●		0.3	0.6		0.3	1	%
		Thermal Regulation	20ms Pulse			0.002	0.02		0.002	0.02	%/W
		Ripple Rejection	VOUT = 10V, f = 120Hz
			CADJ = 0µF	●		60			60		dB
			CADJ = 10µF	●	60	75		60	75		dB
IADJ		Adjust Pin Current		●		45	100		45	100	µA
IADJ		Adjust Pin Current Change	10mA ≤ IOUT ≤ 5A,	●		0.2	5		0.2	5	µA
			3V ≤ (VIN – VOUT) ≤ 35V
		Minimum Load Current	(VIN – VOUT) = 35V	●		3.5	10		3.5	10	mA
ISC		Current Limit	(VIN – VOUT) ≤ 10V		5	8		5	8		A
			DC	●
			0.5ms Peak	●	6	12		6	12		A
			(VIN – VOUT) = 30V, TJ = 25°C			1	2		1		A
VOUT		Temperature Stability		●		1	2		1		%
Temp
VOUT		Long-Term Stability	TA = 125°C, 1000 Hours			0.3	1		0.3	1	%
Time
en		RMS Output Noise (% of VOUT)	10Hz ≤ f ≤ 10kHz			0.001			0.003		%
θJC		Thermal Resistance	K Package				1			1	°C/W
		Junction-to-Case

Note 1: Absolute Maximum Ratings are those values beyond which the life of the device may be impaired.

Note 2: Unless otherwise specified, these specifications apply:

VIN – VOUT = 5V and IOUT = 2.5A. These specifications are applicable for power dissipations up to 50W.

Note 3: See thermal regulation specifications for changes in output voltage due to heating effects. Load and line regulation are measured at a constant junction temperature by low duty cycle pulse testing.

3

LT138A/LT338A

LM138/LM338

TYPICAL PERFORWAUCE CHARACTERISTICS

		Load Regulation
	0.2
			VIN = 15V
(%)	0.1		VOUT = 10V
			PRELOAD = 50mA
DEVIATION
	0							IOUT = 3A
VOLTAGE	– 0.1							IOUT = 5A
	– 0.2
OUTPUT	– 0.3
	– 0.4
												0 25												100
	–75 – 50 – 25																	50				75				125			150
											TEMPERATURE (°C)
																										138/338 G01
				Temperature Stability
VOLTAGE (V)	1.270
	1.260
	1.250
REFERENCE
	1.240
	1.230
					–25					0		25						50				75		100		125			150
			–50
												TEMPERATURE (°C)
																										138A/338A G04
		Ripple Rejection
	100
																CADJ				=		10µF
(dB)	80
																	CADJ			= 0µF
REJECTION
	60
RIPPLE	40
			VIN – VOUT = 5V

20IOUT = 500mA f = 120Hz

TJ = 25°C

0

0 5 10 15 20 25 30 35 OUTPUT VOLTAGE (V)

138A/338A G07

Dropout Voltage

4

VOUT = 100mV

(V)

DIFFERENTIAL

3

IOUT = 5A

OUTPUT-

IOUT = 3A

INPUT

2

IOUT = 1A

1

0 25

50 75

100 125

–75 – 50 – 25

150

TEMPERATURE (°C)

138/338 G02

Output Impedance

10

VIN = 15V

VOUT = 10V

(Ω )

1

IOUT = 500mA

IMPEDANCE

0.1

CADJ = COUT

= 0µF

OUTPUT

0.01

10µF

C

ADJ = COUT =

0.001

0.0001

100

1k

10k

100k

1M

10

FREQUENCY (Hz)

138/338 G05

Ripple Rejection

100

80

(dB)

CADJ = 10µF

REJECTION

60

RIPPLE

40

CADJ = 0µF

20VIN = 15V VOUT = 10V

IOUT = 0.2A

0

10

100

1k

10k

100k

1M

FREQUENCY (Hz)

138A/338A G08

Adjustment Current

	65
(µA)	60
	55
CURRENT
	50
ADJUSTMENT
	45
	40
	35
	30
			–25		25								125
	–75									75
					TEMPERATURE (°C)
														138A/338A G03
	Minimum Operating Current
	5
(mA)	4
																°C
										TJ = 150
CURRENT	3					TJ =		25°C
QUIESCENT	2												TJ = – 55°C
	1

0

05 10 15 20 25 30 35 40 INPUT-OUTPUT DIFFERENTIAL (V)

138A/338A G06

Ripple Rejection

	80
					C	ADJ = 10µF
(dB)	70
REJECTIONRIPPLE
	60				CADJ = 0µF
	50
				VIN = 15V
				VOUT = 10V
				f = 120Hz
	40			TCASE = 25°C
		0.1													1									10

OUTPUT CURRENT (A)

138/338 G09

4