Datasheet

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LT1761 Series

1761sff

TYPICAL APPLICATION

DESCRIPTION

100mA, Low Noise,

LDO Micropower

Regulators in TSOT-23

The LT

1761 series are micropower, low noise, low

dropout regulators. With an external 0.01μF bypass

capacitor, output noise drops to 20μV

RMS

over a 10Hz to

100kHz bandwidth. Designed for use in battery-powered

systems, the low 20μA quiescent current makes them an

ideal choice. In shutdown, quiescent current drops to less

than 0.1μA. The devices are capable of operating over an

input voltage from 1.8V to 20V, and can supply 100mA of

output current with a dropout voltage of 300mV. Quiescent

current is well controlled, not rising in dropout as it does

with many other regulators.

The LT1761 regulators are stable with output capacitors as

low as 1μF. Small ceramic capacitors can be used without

the series resistance required by other regulators.

Internal protection circuitry includes reverse battery

protection, current limiting, thermal limiting and reverse

current protection. The device is available in ﬁ xed output

voltages of 1.2V, 1.5V, 1.8V, 2V, 2.5V, 2.8V, 3V, 3.3V and

5V, and as an adjustable device with a 1.22V reference

voltage. The LT1761 regulators are available in the 5-lead

TSOT-23 package.

5V Low Noise Regulator

FEATURES

APPLICATIONS

Low Noise: 20μV

RMS

(10Hz to 100kHz)

Low Quiescent Current: 20μA

Wide Input Voltage Range: 1.8V to 20V

Output Current: 100mA

Very Low Shutdown Current: <0.1μA

Low Dropout Voltage: 300mV at 100mA

Fixed Output Voltages: 1.2V, 1.5V, 1.8V, 2V, 2.5V,

2.8V, 3V, 3.3V, 5V

Adjustable Output from 1.22V to 20V

Stable with 1μF Output Capacitor

Stable with Aluminum, Tantalum or

Ceramic Capacitors

Reverse-Battery Protected

No Reverse Current

No Protection Diodes Needed

Overcurrent and Overtemperature Protected

Available in Tiny 5-Lead TSOT-23 Package

Cellular Phones

Pagers

Battery-Powered Systems

Frequency Synthesizers

Wireless Modems

10Hz to 100kHz Output Noise

SHDN

0.01μF

10μF

1761 TA01

OUT

5.4V TO

20V

BYP

GND

LT1761-5

5V AT100mA

20μV

RMS

NOISE

1μF

OUT

100μV/DIV

20μV

RMS

1761 TA01b

L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks

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

owners.

Summary of content (22 pages)

PAGE 1
LT1761 Series 100mA, Low Noise, LDO Micropower Regulators in TSOT-23 FEATURES DESCRIPTION n The LT®1761 series are micropower, low noise, low dropout regulators. With an external 0.01μF bypass capacitor, output noise drops to 20μVRMS over a 10Hz to 100kHz bandwidth. Designed for use in battery-powered systems, the low 20μA quiescent current makes them an ideal choice. In shutdown, quiescent current drops to less than 0.1μA. The devices are capable of operating over an input voltage from 1.
PAGE 2
LT1761 Series ABSOLUTE MAXIMUM RATINGS (Note 1) IN Pin Voltage .........................................................±20V OUT Pin Voltage ......................................................±20V Input to Output Differential Voltage .........................±20V ADJ Pin Voltage ...................................................... ±7V BYP Pin Voltage .....................................................±0.6V SHDN Pin Voltage .................................................
PAGE 3
LT1761 Series ORDER INFORMATION LEAD FREE FINISH TAPE AND REEL PART MARKING * PACKAGE DESCRIPTION TEMPERATURE RANGE LT1761ES5-5#PBF LT1761ES5-5#TRPBF LTGG 5-Lead Plastic TSOT-23 –40°C to 125°C LT1761IS5-5#PBF LT1761IS5-5#TRPBF LTGG 5-Lead Plastic TSOT-23 –40°C to 125°C LT1761MPS5-5#PBF LT1761MPS5-5#TRPBF LTGG 5-Lead Plastic TSOT-23 –55°C to 125°C LEAD BASED FINISH TAPE AND REEL PART MARKING * PACKAGE DESCRIPTION TEMPERATURE RANGE LT1761ES5-BYP LT1761ES5-BYP#TR LTGC 5-Lead Plastic TSOT-23 –40°C to 125°C LT17
PAGE 4
LT1761 Series ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. (Note 2) PARAMETER CONDITIONS Minimum Input Voltage (Notes 3, 11) ILOAD = 100mA MIN TYP MAX 1.8 2.3 V Regulated Output Voltage (Note 4) LT1761-1.2 VIN = 2V, ILOAD = 1mA 2.3V < VIN < 20V, 1mA < ILOAD < 50mA 2.3V < VIN < 20V, 1mA < ILOAD < 100mA l l 1.185 1.170 1.150 1.2 1.2 1.2 1.215 1.230 1.240 V V V LT1761-1.
PAGE 5
LT1761 Series ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. (Note 2) PARAMETER CONDITIONS Load Regulation LT1761-1.2 LT1761-1.5 LT1761-1.8 LT1761-2 LT1761-2.5 LT1761-2.8 LT1761-3 LT1761-3.3 LT1761-5 LT1761 (Note 3) Dropout Voltage VIN = VOUT(NOMINAL) (Notes 5, 6, 11) MIN VIN = 2.3V, ΔILOAD = 1mA to 50mA VIN = 2.3V, ΔILOAD = 1mA to 50mA VIN = 2.3V, ΔILOAD = 1mA to 100mA VIN = 2.
PAGE 6
LT1761 Series ELECTRICAL CHARACTERISTICS The l denotes the speciﬁcations which apply over the full operating temperature range, otherwise speciﬁcations are at TA = 25°C. (Note 2) PARAMETER CONDITIONS GND Pin Current VIN = VOUT(NOMINAL) (Notes 5, 7) ILOAD = 0mA ILOAD = 1mA ILOAD = 10mA ILOAD = 50mA ILOAD = 100mA MIN Output Voltage Noise COUT = 10μF, CBYP = 0.
PAGE 7
LT1761 Series TYPICAL PERFORMANCE CHARACTERISTICS Guaranteed Dropout Voltage 500 450 450 350 TJ = 125°C 300 250 TJ = 25°C 200 150 = TEST POINTS 450 400 TJ ≤ 125°C 350 300 TJ ≤ 25°C 250 200 150 350 250 150 50 50 50 10 20 30 40 50 60 70 80 90 100 OUTPUT CURRENT (mA) 1.220 OUTPUT VOLTAGE (V) 25 VSHDN = VIN 20 15 10 1.528 IL = 1mA 1.215 1.521 1.210 1.514 1.205 1.200 1.195 1.190 1.185 5 0 –50 VSHDN = 0V –25 0 25 50 75 100 125 1.180 –50 –25 0 25 50 75 1.507 1.500 1.
PAGE 8
LT1761 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1761-2.8 Output Voltage 3.060 IL = 1mA LT1761-3.3 Output Voltage 3.360 IL = 1mA 3.045 3.345 2.82 3.030 3.330 2.81 2.80 2.79 2.78 2.77 OUTPUT VOLTAGE (V) 2.83 OUTPUT VOLTAGE (V) OUTPUT VOLTAGE (V) 2.84 LT1761-3 Output Voltage 3.015 3.000 2.985 2.970 2.955 2.76 –50 0 –25 25 50 75 100 0 –25 TEMPERATURE (°C) 25 50 75 100 3.270 125 3.240 –50 1.235 5.04 1.230 5.00 4.98 4.96 4.94 0 25 50 75 100 125 1.225 1.220 1.215 1.
PAGE 9
LT1761 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1761-2.5 Quiescent Current LT1761-2.8 Quiescent Current 200 200 125 100 75 50 VSHDN = VIN 25 3 4 5 6 7 INPUT VOLTAGE (V) 125 100 75 50 VSHDN = VIN 0 9 8 0 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 9 8 100 75 50 VSHDN = VIN 9 125 100 75 50 VSHDN = VIN 1 2 3 4 5 6 7 INPUT VOLTAGE (V) RL = 12Ω IL = 100mA* 1.50 1.25 RL = 24Ω IL = 50mA* 1.00 0.75 RL = 1.2k IL = 1mA* 0.50 0.
PAGE 10
LT1761 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1761-2.5 GND Pin Current 2.50 2.25 2.00 RL = 20Ω IL = 100mA* 1.75 1.50 1.25 RL = 40Ω IL = 50mA* 1.00 0.75 RL = 2k IL = 1mA* 0.50 0.25 RL = 25Ω IL = 100mA 2.00 1.75 1.50 1.25 RL = 50Ω IL = 50mA* 1.00 0.75 RL = 2.5k IL = 1mA* 0.50 RL = 200Ω IL = 10mA* 0.25 0 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 2.00 RL = 30Ω IL = 100mA* 1.25 RL = 60Ω IL = 50mA* 0.75 RL = 3k IL = 1mA* 0.50 0.
PAGE 11
LT1761 Series TYPICAL PERFORMANCE CHARACTERISTICS SHDN Pin Input Current 1.0 0.9 0.9 IL = 100mA 0.8 0.7 0.6 IL = 1mA 0.5 0.4 0.3 0.2 SHDN Pin Input Current 1.4 SHDN PIN INPUT CURRENT (μA) 1.0 SHDN PIN INPUT CURRENT (μA) 0.8 0.7 0.6 0.5 0.4 0.3 0.2 0.1 0.
PAGE 12
LT1761 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1761-5 Input Ripple Rejection 80 80 CBYP = 0.01μF 70 CBYP = 1000pF RIPPLE REJECTION (dB) 60 50 CBYP = 100pF 40 30 20 IL = 100mA VIN = VOUT(NOMINAL) + 1V + 50mVRMS RIPPLE COUT = 10μF 10 100 60 50 40 30 20 VIN = VOUT (NOMINAL) + 1V + 0.5VP-P RIPPLE AT f = 120Hz IL = 50mA 10 0 –50 0 10 2.
PAGE 13
LT1761 Series TYPICAL PERFORMANCE CHARACTERISTICS LT1761-5 10Hz to 100kHz Output Noise CBYP = 0pF RMS Output Noise vs Load Current (10Hz to 100kHz) LT1761-5 10Hz to 100kHz Output Noise CBYP = 100pF 160 COUT = 10μF CBYP = 0 CBYP = 0.01μF LT1761-5 120 VOUT 100μV/DIV VOUT 100μV/DIV 100 80 LT1761-BYP 60 40 LT1761-5 20 COUT = 10μF IL = 100mA LT1761-BYP 10 0.
PAGE 14
LT1761 Series PIN FUNCTIONS IN (Pin 1): Input. Power is supplied to the device through the IN pin. A bypass capacitor is required on this pin if the device is more than six 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 15
LT1761 Series APPLICATIONS INFORMATION The LT1761 series are 100mA low dropout regulators with micropower quiescent current and shutdown. The devices are capable of supplying 100mA at a dropout voltage of 300mV. Output voltage noise can be lowered to 20μVRMS over a 10Hz to 100kHz bandwidth with the addition of a 0.01μF reference bypass capacitor. Additionally, the reference bypass capacitor will improve transient response of the regulator, lowering the settling time for transient load conditions.
PAGE 16
LT1761 Series APPLICATIONS INFORMATION The LT1761 regulators are designed to be stable with a wide range of output capacitors. The ESR of the output capacitor affects stability, most notably with small capacitors. A minimum output capacitor of 1μF with an ESR of 3Ω or less is recommended to prevent oscillations. The LT1761-X is a micropower device and output transient response will be a function of output capacitance.
PAGE 17
LT1761 Series APPLICATIONS INFORMATION Voltage and temperature coefﬁcients are not the only sources of problems. Some ceramic capacitors have a piezoelectric response. A piezoelectric device generates voltage across its terminals due to mechanical stress, similar to the way a piezoelectric accelerometer or microphone works. For a ceramic capacitor the stress can be induced by vibrations in the system or thermal transients.
PAGE 18
LT1761 Series APPLICATIONS INFORMATION and a maximum ambient temperature of 50°C, what will the maximum junction temperature be? The power dissipated by the device will be equal to: IOUT(MAX)(VIN(MAX) – VOUT) + IGND(VIN(MAX)) where, IOUT(MAX) = 50mA VIN(MAX) = 6V IGND at (IOUT = 50mA, VIN = 6V) = 1mA So, P = 50mA(6V – 3.3V) + 1mA(6V) = 0.14W The thermal resistance will be in the range of 125°C/W to 150°C/W depending on the copper area.
PAGE 19
LT1761 Series APPLICATIONS INFORMATION In situations where the ADJ pin is connected to a resistor divider that would pull the ADJ pin above its 7V clamp voltage if the output is pulled high, the ADJ pin input current must be limited to less than 5mA. For example, a resistor divider is used to provide a regulated 1.5V output from the 1.22V reference when the output is forced to 20V.
PAGE 20
LT1761 Series PACKAGE DESCRIPTION S5 Package 5-Lead Plastic TSOT-23 (Reference LTC DWG # 05-08-1635) 0.62 MAX 0.95 REF 2.90 BSC (NOTE 4) 1.22 REF 1.4 MIN 3.85 MAX 2.62 REF 2.80 BSC 1.50 – 1.75 (NOTE 4) PIN ONE RECOMMENDED SOLDER PAD LAYOUT PER IPC CALCULATOR 0.30 – 0.45 TYP 5 PLCS (NOTE 3) 0.95 BSC 0.80 – 0.90 0.20 BSC 0.01 – 0.10 1.00 MAX DATUM ‘A’ 0.30 – 0.50 REF 0.09 – 0.20 (NOTE 3) NOTE: 1. DIMENSIONS ARE IN MILLIMETERS 2. DRAWING NOT TO SCALE 3. DIMENSIONS ARE INCLUSIVE OF PLATING 4.
PAGE 21
LT1761 Series REVISION HISTORY (Revision history begins at Rev F) REV DATE DESCRIPTION PAGE NUMBER F 5/10 Added MP-grade 2, 3 Added Typical Application 22 1761sff Information furnished by Linear Technology Corporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no representation that the interconnection of its circuits as described herein will not infringe on existing patent rights.
PAGE 22
LT1761 Series TYPICAL APPLICATION Noise Bypassing Provides Soft-Start Startup Time 100 IN VIN 5.4V TO 20V 5V AT 100mA OUT LT1761-5 1μF CBYP 10μF OFF ON STARTUP TIME (ms) BYP SHDN GND 1761 TA02a 10 1 0.1 10 100 1000 10000 CBYP (pF) 1761 TA02b RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20μA IQ Includes 2.