ST LD2981ABM25TR, LD2981ABU25TR, LD2981CU25TR, LD2981ABM30TR, LD2981ABU30TR User Manual

LD2981ABxx

LD2981Cxx

Ultra low drop voltage regulators with inhibit low ESR output capacitors compatible

Features

■Stable with low ESR ceramic capacitors

■Ultra low dropout voltage (0.17 V typ. at 100 mA load, 7 mV typ. at 1 mA load)

■Very low quiescent current (80 µA typ. at no load in on mode; max 1 µA in off mode)

■Guaranteed output current up to 100mA

■Logic-controlled electronic shutdown

■Output voltage of 2.5; 3.0; 3.3; 5.0 V

■Internal current and thermal limit

■± 0.75 % tolerance output voltage available (A version)

■Output low noise voltage 160 µVRMS

■Temperature range: -40 to 125 °C

■Smallest package SOT23-5L and SOT-89

■Fast dynamic response to line and load changes

SOT23-5L

SOT-89

logic control function is available on pin n° 3 (TTL compatible). This means that when thedevice is used as local regulator, it is possible to put a part of the board in standby, decreasing the total power consumption. The LD2981AB/C is designed to work with low ESR ceramic capacitor. Typical applications are in cellular phone, palmtop/laptop computer, personal digital assistant (PDA), personal stereo, camcorder and camera.

Description

The LD2981AB/C series are 100 mA fixed-output voltage regulator. The low drop-voltage and the ultra low quiescent current make them suitable for low noise, low power applications and in battery powered systems.

The quiescent current in sleep mode is less than 1 µA when INHIBIT pin is pulled low. Shutdown

Table 1.	Device summary
	Part numbers			Output voltage
	AB Version		C Version
	LD2981ABXX25		LD2981CXX25	2.5 V
	LD2981ABXX30		LD2981CXX30	3.0 V
	LD2981ABXX33		LD2981CXX33	3.3 V
	LD2981ABXX50		LD2981CXX50	5.0 V
July 2008			Rev 14	1/23

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LD2981ABxx - LD2981Cxx

Contents

1	Diagram . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. 3
2	Pin configuration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		. 4
3	Maximum ratings . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		5
4	Typical application . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		6
5	Electrical characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		7
6	Typical performance characteristics . . . . . . . . . . . . . . . . . . . . . . . . . . .		11
7	Application notes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		14
	7.1	External capacitors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	14
	7.2	Input capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	14
	7.3	Output capacitor . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	14
	7.4	Important . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	14
	7.5	Inhibit input operation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	14
	7.6	Reverse current . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .	15
8	Package mechanical data . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		16
9	Order codes . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		21
10	Revision history . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .		22

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LD2981ABxx - LD2981Cxx	Diagram

1 Diagram

Figure 1. Schematic diagram

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Pin configuration	LD2981ABxx - LD2981Cxx

2 Pin configuration

Figure 2. Pin connections (top view)

								SOT-89
		SOT23-5L

Table 2.	Pin description
Pin n°		Pin n°		Symbol	Name and function
SOT23-5L		SOT-89
1		3		VIN	Input port
2		2		GND	Ground pin
					Control switch ON/OFF. Inhibit is not internally pulled-up; it cannot be
3				INHIBIT	left floating. Disable the device when connected to GND or to a
					positive voltage less than 0.18 V
4				NC	Not connected
5		1		VOUT	Output port

Table 3.	Thermal data
Symbol	Parameter	SOT23-5L	SOT-89	Unit
RthJC	Thermal resistance junction-case	81	15	°C/W
RthJA	Thermal resistance junction-ambient	255	110	°C/W

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LD2981ABxx - LD2981Cxx			Maximum ratings
3	Maximum ratings
Table 4.	Absolute maximum ratings
Symbol		Parameter	Value	Unit
VI		DC input voltage	-0.3 to 16	V
VINH		INHIBIT input voltage	-0.3 to 16	V
IO		Output current	Internally limited
PD		Power dissipation	Internally limited
TSTG		Storage temperature range	-55 to 150	°C
TOP		Operating junction temperature range	-40 to 125	°C
Note:	Absolute maximum ratings are those values beyond which damage to the device may occur.
	Functional operation under these condition is not implied.

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Typical application	LD2981ABxx - LD2981Cxx

4 Typical application

Figure 3. Application circuit

Note:	Inhibit pin is not internally pulled-up then it must not be left floating. Disable the device when
	connected to GND or to a positive voltage less than 0.18 V.

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LD2981ABxx - LD2981Cxx	Electrical characteristics

5 Electrical characteristics

Table 5. Electrical characteristics for LD2981AB (TJ = 25 °C, VI = VO(NOM) +1 V, CI = 1 µF (X7R), CO = 2.2 µF (X7R), IO = 1 mA, VINH = 2 V, unless otherwise specified).

Symbol	Parameter	Test conditions	Min.	Typ.	Max.	Unit
VOP	Operating input voltage		2.5		16	V
		IO = 1 mA	2.481	2.5	2.518
VO	Output voltage	IO = 1 to 100 mA	2.475		2.525	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	2.437		2.562
		IO = 1 mA	2.828	2.85	2.872
VO	Output voltage	IO = 1 to 100 mA	2.822		2.878	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	2.779		2.921
		IO = 1 mA	2.977	3	3.023
VO	Output voltage	IO = 1 to 100 mA	2.970		3.030	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	2.925		3.075
		IO = 1 mA	3.176	3.2	3.224
VO	Output voltage	IO = 1 to 100 mA	3.168		3.232	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	3.12		3.28
		IO = 1 mA	3.275	3.3	3.325
VO	Output voltage	IO = 1 to 100 mA	3.267		3.333	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	3.217		3.383
		IO = 1 mA	3.573	3.6	3.627
VO	Output voltage	IO = 1 to 100 mA	3.564		3.636	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	3.510		3.690
		IO = 1 mA	3.771	3.8	3.829
VO	Output voltage	IO = 1 to 100 mA	3.762		3.838	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	3.705		3.895
		IO = 1 mA	3.97	4	4.03
VO	Output voltage	IO = 1 to 100 mA	3.96		4.04	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	3.9		4.1
		IO = 1 mA	4.664	4.7	4.735
VO	Output voltage	IO = 1 to 100 mA	4.653		4.747	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	4.582		4.817
		IO = 1 mA	4.813	4.85	4.887
VO	Output voltage	IO = 1 to 100 mA	4.801		4.899	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	4.729		4.971
		IO = 1 mA	4.962	5	5.038
VO	Output voltage	IO = 1 to 100 mA	4.950		5.050	V
		IO = 1 to 100 mA, TJ= -40 to 125°C	4.875		5.125
VO	Line regulation	VO(NOM) + 1 < VIN < 16 V, IO = 1 mA		0.003	0.014	%/V
		TJ= -40 to 125°C			0.032

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