ST L4920, L4921 User Manual

L4920

L4920

L4921

VERY LOW DROP ADJUSTABLE REGULATORS

.VERY LOW DROP VOLTAGE

.

ADJUSTABLE OUTPUT VOLTAGE FROM

.1.25V TO 20V

.400mA OUTPUT CURRENT

.LOW QUIESCENT CURRENT

.REVERSE VOLTAGE PROTECTION

+ 60/ − 60V TRANSIENT PEAK VOLTAGE

.PROTECTION

SHORT CIRCUIT PROTECTION WITH FOLD-

.BACK CHARACTERISTICS

THERMAL SHUT-DOWN

DESCRIPTION

The L4920 and L4921 are adjustable voltage regulators with a verylow voltage drop(0.4V typ. at 0.4A Tj = 25°C), low quiescent current and comprehensive on-chip protection.

Thesedevices are protectedagainst load dumpand field decay transients, polarity reversal and over heating.

A foldbackcurrentlimiter protectsagainstload short circuits.

The outputvoltage is adjustablethrough an external divider from 1.25V to 20V. The minimum operating input voltage is 5.2V (TJ = 25°C).

Pentaw att

Minidip (4 + 4)

ORDERING NUMBERS : L4920 (Pentawatt)

L4921 (Minidip)

These regulators are designed for automotive, industrial and consumer applications where low consumption is particularly important.

In battery backup and standby applications the low consumption of these devices extends battery life.

BLOCK DIAGRAM

June 2000

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L4920/L4921

ABSOLUTE MAXIMUM RATINGS

Symbol	Parameter	Value	Unit
Vi	DC Input Operating Voltage	35	V
	DC Reverse Input Voltage
	Transient Input Overvoltages:
	Load Dump:
	5ms ≤ trise ≤ 10ms
	τf Fall time constant = 100ms
	RSOURCE ≥ 0.5Ω
	Field Decay:
	5ms ≤ tfall ≤ 10ms, RSOURCE ≥ 10Ω
	τf Rise time constant = 33ms
TJ, TSTG	Junction and Storage Temperature Range	± 55 to 150	°C

PIN CONNECTIONS (top view)

TEST AND APPLICATION CIRCUIT

C = 100μF is required for stability (ESR ≤ 3Ω over T range)

R2 = 6.2KΩ.

THERMAL DATA

Symbol	Parameter		Minidip	Pentawatt
			(4 + 4)
Rth j-amb	Thermal Resistance Junction-ambient	Max	80 °C/W	60 °C/W
Rth j-pins	Thermal Resistance Junction-pins	Max	15 °C/W	±
Rth j-case	Thermal Resistance Junction-case	Max	±	3.5 °C/W

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L4920/L4921

ELECTRICAL CHARACTERISTICS (forVI =14.4V,TJ = 25°C,VO = 5V,CO = 100μF, unlessOtherwiseSpecified)

Symbol	Parameter	Test Condition		Min.	Typ.	Max.	Unit
VI	Operating Input Voltage	VO ≥ 4.5V, IO = 400mA		VO + 0.7		26	V
		VREF ≤ VO < 4.5V, IO = 400mA		5.2		26	V
VREF	Reference Voltage	5.2V < VI < 26V		1.20	1.25	1.30	V
		5mA ≤ IO ≤ 400mA (*)
VO	Line Regulation	VO + 1V < VI < 26V, VO ≥	4.5V		1	10	mV/V
		IO = 5mA
VO	Load Regulation	5mA ≤ IO ≤ 400mA (*) VO	≥ 4.5V		3	15	mV/V
VD	Dropout Voltage	IO = 10mA			0.05		V
		IO = 150mA			0.2	0.4	V
		IO = 400mA			0.4	0.7	V
IQ	Quiescent Current	IO = 0mA
		VO + 1V < VI <26V			0.8	2	mA
		IO = 400mA (*)
		VO + 1V < VI <26V			65	90	mA
IO	Maximal Output Current				800		mA
IOSC	Short Circuit Output Current (*)				350	500	mA

(*) F oldback protection

ELECTRICAL CHARACTERISTICS (forVI = 14.4V,±40 ≤ TJ ≤ 125°C (note1), VO = 5V,CO = 100μF, unless Otherwise Specified)

Symbol	Parameter	Test Condition				Min.	Typ.	Max.	Unit
VI	Operating Input Voltage	VO ≥ 4.5V, IO = 400mA				VO + 0.9		26	V
		VREF ≤ VO < 4.5V, IO = 400mA				5.2		26	V
VREF	Reference Voltage	5.4V < VI < 26V				1.17	1.25	1.33	V
VO	Line Regulation	VO + 1.2V < VI < 26V,	VO	≥	4.5V		2	15	mV/V
		IO = 5mA
VO	Load Regulation	5mA ≤ IO ≤ 400mA (*)	VO	≥	4.5V		5	25	mV/V
VD	Dropout Voltage	IO = 150mA					0.2	0.4	V
		IO = 400mA					0.4	0.7	V
IQ	Quiescent Current	IO = 0mA
		VO + 1.2V < VI <26V					1,2	3	mA
		IO = 400mA (*)
		VO + 1.2V < VI <26V					80	140	mA
IO	Maximal Output Current						870		mA
IOSC	Short Circuit Output Current (*)						230	500	mA
(*) Foldback protection.
N ote : 1. Design limits are guaranteed (but		not 100% production tested) over			the indicated		temperatu re	and supply	voltage
	ranges. These limits are not used	to calculate outgoing quality levels.

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