Datasheet

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LT1121/LT1121-3.3/LT1121-5

1121fg

TYPICAL APPLICATION

FEATURES

APPLICATIONS

DESCRIPTION

Micropower Low Dropout

Regulators with Shutdown

The LT

1121/LT1121-3.3/LT1121-5 are micropower low

dropout regulators with shutdown. These devices are ca-

pable of supplying

150mA of output current with a dropout

voltage of 0.4V. Designed for use in battery-powered sys-

tems, the low quiescent current, 30µA operating and 16µA

in shutdown, makes them an ideal choice. The quiescent

current is well-controlled;

it does not rise in dropout as it

does with many other low dropout PNP regulators.

Other features of the LT1121/LT1121-3.3/LT1121-5 include

the ability to operate with very small output capacitors.

They are stable with only 0.33µF on the output while most

older devices require between 1µF and 100µF for stability.

Small ceramic capacitors can be used, enhancing manu-

facturability. Also the input may

be connected to ground

or a reverse voltage without reverse current flow from

output to input. This makes the LT1121 series ideal for

backup power situations where the output is held high and

the input is at ground or reversed. Under these conditions

only 16µA will flow from the output pin to ground.

5V Battery-Powered Supply with Shutdown

0.4V Dropout Voltage

150mA Output Current

30µA Quiescent Current

No Protection Diodes Needed

Adjustable Output from 3.75V to 30V

3.3V and 5V Fixed Output Voltages

Controlled Quiescent Current in Dropout

Shutdown

16µA Quiescent Current in Shutdown

Stable with 0.33µF Output Capacitor

Reverse Battery Protection

No Reverse Current with Input Low

Thermal Limiting

Available in the 8-Lead SO, 8-Lead PDIP, 3-Lead

SOT-23 and 3-Lead TO-92 Packages

Low Current Regulator

Regulator for Battery-Powered Systems

Post Regulator for Switching Supplies

Dropout Voltage

OUT

LT1121-3.3

GND

3.3V

OUT

150mA

1μF

SOLID TANTALUM

LT1121 • TA01

SHDN

(PIN 5)

<0.25

>2.8

OUTPUT

OFF

SHDN

OUTPUT CURRENT (mA)

DROPOUT VOLTAGE (V)

0.3

0.4

0.5

60 100 160

0.2

0.1

20 40

120 140

LT1121 • TA02

L, LT , LT C , LT M , Linear Technology and the Linear logo are registered trademarks of Linear

Technology Corporation. All other trademarks are the property of their respective owners.

Summary of content (16 pages)

PAGE 1
LT1121/LT1121-3.3/LT1121-5 Micropower Low Dropout Regulators with Shutdown FEATURES n n n n n n n n n n n n n n DESCRIPTION 0.4V Dropout Voltage 150mA Output Current 30µA Quiescent Current No Protection Diodes Needed Adjustable Output from 3.75V to 30V 3.3V and 5V Fixed Output Voltages Controlled Quiescent Current in Dropout Shutdown 16µA Quiescent Current in Shutdown Stable with 0.
PAGE 2
LT1121/LT1121-3.3/LT1121-5 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage LT1121............................................................... ± 30V LT1121HV................................................ +36V, – 30V Output Pin Reverse Current .................................. 10mA Adjust Pin Current ................................................. 10mA Shutdown Pin Input Voltage (Note 2)........... 6.5V, – 0.6V Shutdown Pin Input Current (Note 2) ...................
PAGE 3
LT1121/LT1121-3.3/LT1121-5 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING PACKAGE DESCRIPTION TEMPERATURE RANGE LT1121AHVCS8#PBF LT1121AHVCS8#TRPBF 121AHV 8-Lead Plastic S0 0°C to 125°C LT1121AIS8#PBF LT1121AIS8#TRPBF 121AI 8-Lead Plastic S0 –40°C to 125°C LT1121AIS8-3.3#PBF LT1121AIS8-3.
PAGE 4
LT1121/LT1121-3.3/LT1121-5 ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the full operating temperature range, otherwise specifications are at TA = 25°C.
PAGE 5
LT1121/LT1121-3.3/LT1121-5 TYPICAL PERFORMANCE CHARACTERISTICS Dropout Voltage 0.6 0.6 TJ ≤ 125°C 0.5 0.4 TJ ≤ 25°C 0.3 0.2 0.1 0 Quiescent Current 50 ILOAD = 150mA ILOAD = 100mA 0.5 0.4 0.3 ILOAD = 50mA 0.2 ILOAD = 1mA 0.1 = TEST POINTS 0 0 –50 40 60 80 100 120 140 160 OUTPUT CURRENT (mA) 20 50 25 0 75 TEMPERATURE (°C) –25 100 1121 G01 VSHDN = OPEN 40 2 3 4 5 6 7 INPUT VOLTAGE (V) 80 VSHDN = OPEN 60 40 20 VSHDN = 0V 1 8 9 0 10 1 0 2 3.32 3.30 3.28 3.26 3.
PAGE 6
LT1121/LT1121-3.3/LT1121-5 TYPICAL PERFORMANCE CHARACTERISTICS 800 TJ = 25°C RLOAD = 130Ω ILOAD = 25mA* 600 500 RLOAD = 330Ω ILOAD = 10mA* 400 300 *FOR VOUT = 3.3V 200 RLOAD = 3.
PAGE 7
LT1121/LT1121-3.
PAGE 8
LT1121/LT1121-3.3/LT1121-5 TYPICAL PERFORMANCE CHARACTERISTICS LT1121-5 Load Transient Response Load Regulation ΔILOAD = 1mA TO 150mA OUTPUT VOLTAGE DEVIATION (V) LT1121* –10 LT1121-3.3 –15 –20 VIN = 6V 0.2 CIN = 0.1μF = 1μF C 0.1 OUT 0 –0.1 –0.2 VIN = 6V 0.2 CIN = 0.1μF COUT = 3.3μF 0.1 0 –0.1 –0.2 LT1121-5 –30 –35 * ADJ PIN TIED TO OUTPUT PIN –40 –50 –25 50 0 75 25 TEMPERATURE (°C) 100 125 150 100 0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1.
PAGE 9
LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION The LT1121 is a micropower low dropout regulator with shutdown, capable of supplying up to 150mA of output current at a dropout voltage of 0.4V. The device operates with very low quiescent current (30µA). In shutdown the quiescent current drops to only 16µA. In addition to the low quiescent current the LT1121 incorporates several protection features which make it ideal for use in batterypowered systems.
PAGE 10
LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION NC leads were connected to the ground plane. Table 1. N8 Package* COPPER AREA Table 5. TO-92 Package THERMAL RESISTANCE Package alone 220ºC/W Package soldered into PC board with plated through holes only 175ºC/W Package soldered into PC board with 1/4 sq.
PAGE 11
LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION Table 6. Suggested Series Resistor Values OUTPUT CAPACITANCE SUGGESTED SERIES RESISTOR 0.33µF 2Ω 0.47µF 1Ω 0.68µF 1Ω >1µF None Needed Protection Features The LT1121 incorporates several protection features which make it ideal for use in battery-powered circuits.
PAGE 12
LT1121/LT1121-3.3/LT1121-5 APPLICATIONS INFORMATION 5 VOUT = 3.3V (LT1121-3.3) VOUT = 5V (LT1121-5) 4 INPUT CURRENT (μA) When the input of the LT1121 is forced to a voltage below its nominal output voltage and its output is held high, the reverse output current will still follow the curve in Figure 2. This condition can occur if the input of the LT1121 is connected to a discharged (low voltage) battery and the output is held up by either a backup battery or by a second regulator circuit.
PAGE 13
LT1121/LT1121-3.3/LT1121-5 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. N Package 8-Lead PDIP (Narrow .300 Inch) (Reference LTC DWG # 05-08-1510 Rev I) .300 – .325 (7.620 – 8.255) ( +.035 .325 –.015 +0.889 8.255 –0.381 .130 ±.005 (3.302 ±0.127) .045 – .065 (1.143 – 1.651) .065 (1.651) TYP .008 – .015 (0.203 – 0.381) ) .400* (10.160) MAX 8 7 6 5 1 2 3 4 .255 ±.015* (6.477 ±0.381) .120 (3.048) .020 MIN (0.508) MIN .
PAGE 14
LT1121/LT1121-3.3/LT1121-5 PACKAGE DESCRIPTION Please refer to http://www.linear.com/designtools/packaging/ for the most recent package drawings. ST Package 3-Lead Plastic SOT-223 (Reference LTC DWG # 05-08-1630) .248 – .264 (6.30 – 6.71) .129 MAX .114 – .124 (2.90 – 3.15) .059 MAX .264 – .287 (6.70 – 7.30) .248 BSC .130 – .146 (3.30 – 3.71) .039 MAX .059 MAX .090 BSC .181 MAX .033 – .041 (0.84 – 1.04) .0905 (2.30) BSC RECOMMENDED SOLDER PAD LAYOUT 10° – 16° .010 – .014 (0.25 – 0.
PAGE 15
LT1121/LT1121-3.3/LT1121-5 REVISION HISTORY (Revision history begins at Rev G) REV DATE DESCRIPTION G 05/12 Changed Order Information top marking for 8-lead SO 3.3V and 5V options, C-grade PAGE NUMBER 2 1121fg Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use.
PAGE 16
LT1121/LT1121-3.3/LT1121-5 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20µA IQ Includes 2.5V Reference and Comparator LT1129 700mA Micropower Low Dropout Regulator 50µA Quiescent Current LT1175 500mA Negative Low Dropout Micropower Regulator 45µA IQ, 0.