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LT1129/LT1129-3.3/LT1129-5

112935ff

TYPICAL APPLICATION

DESCRIPTION

Micropower Low Dropout

Regulators with Shutdown

The LT

1129/LT1129-3.3/LT1129-5 are micropower low

dropout regulators with shutdown. The devices are capable

of supplying 700mA of output current with a dropout

voltage of 400mV at maximum output. Designed for use

in battery-powered systems, the low quiescent current,

50μA operating and 16μA in shutdown, make them an ideal

choice. The quiescent current does not rise in dropout as

it does with many other low dropout PNP regulators.

Other features of the LT1129 /LT1129-3.3/LT1129-5 include

the ability to operate with small output capacitors. They

are stable with only 3.3μF on the output while most older

devices require between 10μF and 100μF for stability. Also

the input may be connected to ground or a reverse voltage

without reverse current ﬂ ow from output to input. This

makes the LT1129/LT1129-3.3/LT1129-5 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 ﬂ ow from the output pin to ground. The

devices are available in 5-lead TO-220, 5-lead DD-Pak and

3-lead SOT-223 packages.

FEATURES

APPLICATIONS

400mV Dropout Voltage

700mA Output Current

50μA Quiescent Current

No Protection Diodes Needed

Adjustable Output from 3.8V to 30V

3.3V and 5V Fixed Output Voltages

Controlled Quiescent Current in Dropout

Shutdown

16μA Quiescent Current in Shutdown

Stable with 3.3μF Output Capacitor

Reverse Battery Protection

No Reverse Output Current

Thermal Limiting

Surface Mount SOT-223 and DD-Pak Packages

Low Current Regulator

Regulator for Battery-Powered Systems

Post Regulator for Switching Supplies

5V to 3.3V Logic Regulator

5V Supply with Shutdown

IN OUT

LT1129-5

GND

5V OUT

500mA

> 5.5V

3.3μF

SOLID TANTALUM

SENSE

112935 TA01

SHDN

(PIN 4)

< 0.25

> 2.8

OUTPUT

OFF

SHDN

OUTPUT CURRENT (A)

DROPOUT VOLTAGE (V)

0.4

0.5

0.6

0.3 0.5

0.3

0.2

0.1 0.2

0.4 0.6 0.7

0.1

112935 TA02

Dropout Voltage

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

All other trademarks are the property of their respective owners.

Summary of content (16 pages)

PAGE 1
LT1129/LT1129-3.3/LT1129-5 Micropower Low Dropout Regulators with Shutdown FEATURES DESCRIPTION n The LT ®1129/LT1129-3.3/LT1129-5 are micropower low dropout regulators with shutdown. The devices are capable of supplying 700mA of output current with a dropout voltage of 400mV at maximum output. Designed for use in battery-powered systems, the low quiescent current, 50μA operating and 16μA in shutdown, make them an ideal choice.
PAGE 2
LT1129/LT1129-3.3/LT1129-5 ABSOLUTE MAXIMUM RATINGS (Note 1) Input Voltage ...................................................... ± 30V* Output Pin Reverse Current ................................. 10mA Sense Pin Current ................................................ 10mA Adjust Pin Current ................................................ 10mA Sense Pin, Adjust Pin Reverse Voltage ............... – 0.6V Shutdown Pin Input Voltage (Note 2) ......... 6.5V, – 0.6V Shutdown Pin Input Current (Note 2) ......
PAGE 3
LT1129/LT1129-3.3/LT1129-5 ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT1129IS8-5#PBF LT1129IS8-5#TRPBF 1129I5 8-Lead Plastic SO –40°C to 125°C LT1129CST-3.3#PBF LT1129CST-3.3#TRPBF 11293 3-Lead Plastic SOT-223 0°C to 125°C LT1129IST-3.3#PBF LT1129IST-3.3#TRPBF 129I3 3-Lead Plastic SOT-223 –40°C to 125°C LT1129MPST-3.3#PBF LT1129MPST-3.
PAGE 4
LT1129/LT1129-3.3/LT1129-5 ORDER INFORMATION LEAD BASED FINISH TAPE AND REEL PART MARKING* PACKAGE DESCRIPTION TEMPERATURE RANGE LT1129CT-5 LT1129CT-5#TR LT1129CT-5 5-Lead Plastic TO-220 0°C to 125°C LT1129IT-5 LT1129IT-5#TR LT1129IT-5 5-Lead Plastic TO-220 –40°C to 125°C Consult LTC Marketing for parts speciﬁed with wider operating temperature ranges. *The temperature grade is identiﬁed by a label on the shipping container. For more information on lead free part marking, go to: http://www.
PAGE 5
LT1129/LT1129-3.3/LT1129-5 ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. SYMBOL CONDITIONS Ripple Rejection VIN – VOUT = 1V (Avg), VRIPPLE = 0.5VP-P, fRIPPLE = 120Hz, ILOAD = 0.7A, TJ = 25°C Current Limit VIN – VOUT = 7V, TJ = 25°C Input Reverse Leakage Current VIN = –20V, VOUT = 0V Reverse Output Current (Note 11) LT1129-3.3 LT1129-5 LT1129 (Note 5) MIN TYP 52 64 MAX 1.
PAGE 6
LT1129/LT1129-3.3/LT1129-5 TYPICAL PERFORMANCE CHARACTERISTICS LT1129-3.3 Quiescent Current LT1129-5 Quiescent Current 250 ILOAD = 0 RLOAD = ∞ 225 QUIESCENT CURRENT (μA) 200 175 150 VSHDN = OPEN (HI) 125 100 75 50 VSHDN = 0V 25 250 ILOAD = 0 RLOAD = ∞ 225 200 175 150 VSHDN = OPEN (HI) 125 100 75 50 VSHDN = 0V 25 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 0 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 LT1129-3.3 Output Voltage 10 3.300 3.275 3.250 3.
PAGE 7
LT1129/LT1129-3.3/LT1129-5 TYPICAL PERFORMANCE CHARACTERISTICS LT1129-3.3 Ground Pin Current LT1129-5 Ground Pin Current 60 50 40 RLOAD = 4.7Ω ILOAD = 700mA* 30 RLOAD = 6.6Ω ILOAD = 500mA* 20 RLOAD = 11Ω ILOAD = 300mA* 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 50 40 RLOAD = 7.1Ω ILOAD = 700mA* 30 RLOAD = 10Ω ILOAD = 500mA* 20 0 8 9 RLOAD = 16.6Ω ILOAD = 300mA* 10 *FOR VOUT = 3.3V 0 60 TJ = 25°C VOUT = VSENSE 10 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 TJ = 25°C 30 20 TJ = –50°C 10 0 0.2 0.
PAGE 8
LT1129/LT1129-3.3/LT1129-5 TYPICAL PERFORMANCE CHARACTERISTICS Reverse Output Current Current Limit 20 15 10 5 1.2 SHORT-CIRCUIT CURRENT (A) SHORT-CIRCUIT CURRENT (A) 1.0 0.8 0.6 0.4 0.2 0 –50 0 50 25 0 75 TEMPERATURE (°C) –25 100 0 125 1 4 3 2 5 INPUT VOLTAGE (V) Reverse Output Current TJ = 25°C, VIN = 0V VOUT = VSENSE (LT1129-3.3/LT1129-5) VOUT = VADJ (LT1129) CURRENT FLOWS INTO DEVICE 70 60 50 0.6 0.4 VIN = 7V VOUT = 0V 0 –50 7 LT1129 LT1129-3.
PAGE 9
LT1129/LT1129-3.3/LT1129-5 PIN FUNCTIONS Input Pin: Power is supplied to the device through the input pin. The input pin should be bypassed to ground if the device is more than 6 inches away from the main input ﬁlter capacitor. In general, the output impedance of a battery rises with frequency so it is advisable to include a bypass capacitor in battery-powered circuits. A bypass capacitor in the range of 1μF to 10μF is sufﬁcient.
PAGE 10
LT1129/LT1129-3.3/LT1129-5 APPLICATIONS INFORMATION Adjustable Operation Thermal Considerations The adjustable version of the LT1129 has an output voltage range of 3.75V to 30V. The output voltage is set by the ratio of two external resistors as shown in Figure 2. The device servos the output voltage to maintain the voltage at the adjust pin at 3.75V. The current in R1 is then equal to 3.75V/R1. The current in R2 is equal to the sum of the current in R1 and the adjust pin bias current.
PAGE 11
LT1129/LT1129-3.3/LT1129-5 OPERATION copper. This data can be used as a rough guideline in estimating thermal resistance. The thermal resistance for each application will be affected by thermal interactions with other components as well as board size and shape. Some experimentation will be necessary to determine the actual value. where, IOUT MAX = 500mA VIN MAX = 5.5V IGND at (IOUT = 500mA, VIN = 5.5V) = 25mA Table 1.
PAGE 12
LT1129/LT1129-3.3/LT1129-5 APPLICATIONS INFORMATION Current limit protection and thermal overload protection are intended to protect the device against current overload conditions at the output of the device. For normal operation, the junction temperature should not exceed 125°C. The input of the device will withstand reverse voltages of 30V. Current ﬂow into the device will be limited to less than 1mA (typically less than 100μA) and no negative voltage will appear at the output.
PAGE 13
LT1129/LT1129-3.3/LT1129-5 APPLICATIONS INFORMATION Table 4.
PAGE 14
LT1129/LT1129-3.3/LT1129-5 PACKAGE DESCRIPTION Q Package 5-Lead Plastic DD Pak (LTC DWG # 05-08-1461) .256 (6.502) .060 (1.524) TYP .060 (1.524) .390 – .415 (9.906 – 10.541) .165 – .180 (4.191 – 4.572) .045 – .055 (1.143 – 1.397) 15° TYP .060 (1.524) .183 (4.648) +.008 .004 –.004 +0.203 0.102 –0.102 .059 (1.499) TYP .330 – .370 (8.382 – 9.398) ( ) .095 – .115 (2.413 – 2.921) .075 (1.905) .300 (7.620) +.012 .143 –.020 +0.305 3.632 –0.
PAGE 15
LT1129/LT1129-3.3/LT1129-5 PACKAGE DESCRIPTION S8 Package 8-Lead Plastic Small Outline (Narrow 0.150) (LTC DWG # 05-08-1610) .189 – .197 (4.801 – 5.004) NOTE 3 .045 ±.005 .050 BSC 8 .245 MIN .160 ±.005 7 6 5 .053 – .069 (1.346 – 1.752) .150 – .157 (3.810 – 3.988) NOTE 3 .228 – .244 (5.791 – 6.197) .030 ±.005 TYP 1 2 3 INCHES (MILLIMETERS) 2. DRAWING NOT TO SCALE .050 (1.270) BSC .014 – .019 (0.355 – 0.483) TYP .010 – .020 s 45° (0.254 – 0.508) 4 RECOMMENDED SOLDER PAD LAYOUT NOTE: 1.
PAGE 16
LT1129/LT1129-3.3/LT1129-5 TYPICAL APPLICATION T Package 5-Lead Plastic TO-220 (Standard) (LTC DWG # 05-08-1421) .165 – .180 (4.191 – 4.572) .147 – .155 (3.734 – 3.937) DIA .390 – .415 (9.906 – 10.541) .045 – .055 (1.143 – 1.397) .230 – .270 (5.842 – 6.858) .570 – .620 (14.478 – 15.748) .460 – .500 (11.684 – 12.700) .330 – .370 (8.382 – 9.398) .620 (15.75) TYP .700 – .728 (17.78 – 18.491) SEATING PLANE .152 – .202 .260 – .320 (3.861 – 5.131) (6.60 – 8.13) .095 – .115 (2.413 – 2.921) .155 – .