Datasheet

ManualsBrandsLINEAR TECHNOLOGY ManualsVoltage RegulatorsLT1762EMS8#PBF

LT1762 Series

1762fa

150mA, Low Noise, LDO

Micropower Regulators

■

Low Noise: 20µV

RMS

(10Hz to 100kHz)

■

Low Quiescent Current: 25µA

■

Wide Input Voltage Range: 1.8V to 20V

■

Output Current: 150mA

■

Very Low Shutdown Current: < 1

■

Low Dropout Voltage: 270mV

■

No Protection Diodes Needed

■

Fixed Output Voltages: 2.5V, 3V, 3.3V, 5V

■

Adjustable Output from 1.22V to 20V

■

Stable with 2.2µF Output Capacitor

■

Stable with Aluminum, Tantalum or

Ceramic Capacitors

■

Reverse Battery Protection

■

No Reverse Current

■

Overcurrent and Overtemperature Protected

■

8-Lead MSOP Package

The LT

1762 series are micropower, low noise, low

dropout regulators. The devices are capable of supplying

150mA of output current with a dropout voltage of 270mV.

Designed for use in battery-powered systems, the low

25µA quiescent current makes them an ideal choice.

Quiescent current is well controlled; it does not rise in

dropout as it does with many other regulators.

A key feature of the LT1762 regulators is low output noise.

With the addition of an external 0.01µF bypass capacitor,

output noise drops to 20µV

RMS

over a 10Hz to 100kHz

bandwidth. The LT1762 regulators are stable with output

capacitors as low as 2.2µF. Small ceramic capacitors can

be used without the series resistance required by other

regulators.

Internal protection circuitry includes reverse battery pro-

tection, current limiting, thermal limiting and reverse

current protection. The parts come in fixed output volt-

ages of 2.5V, 3V, 3.3V and 5V, and as an adjustable device

with a 1.22V reference voltage. The LT1762 regulators are

available in the 8-lead MSOP package.

Dropout Voltage

3.3V Low Noise Regulator

■

Cellular Phones

■

Battery-Powered Systems

■

Frequency Synthesizers

■

Noise-Sensitive Instrumentation Systems

SHDN

0.01µF

10µF

1762 TA01

OUT

SENSE

3.7V TO

20V

BYP

GND

LT1762-3.3

3.3V AT 150mA

20µV

RMS

NOISE

1µF

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

All other trademarks are the property of their respective owners.

OUTPUT CURRENT (mA)

DROPOUT VOLTAGE (mV)

400

350

300

250

200

150

100

80 100 120 140

1762 TA02

160

DESCRIPTIO

FEATURES

APPLICATIO S

TYPICAL APPLICATIO

Summary of content (16 pages)

PAGE 1
LT1762 Series 150mA, Low Noise, LDO Micropower Regulators U FEATURES DESCRIPTIO ■ The LT ®1762 series are micropower, low noise, low dropout regulators. The devices are capable of supplying 150mA of output current with a dropout voltage of 270mV. Designed for use in battery-powered systems, the low 25µA quiescent current makes them an ideal choice. Quiescent current is well controlled; it does not rise in dropout as it does with many other regulators.
PAGE 2
LT1762 Series W U PACKAGE/ORDER INFORMATION W W U W (Note 1) IN Pin Voltage ........................................................ ±20V OUT Pin Voltage .................................................... ±20V Input to Output Differential Voltage ....................... ±20V SENSE Pin Voltage ............................................... ±20V ADJ Pin Voltage ...................................................... ±7V BYP Pin Voltage.................................................... ±0.
PAGE 3
LT1762 Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C.
PAGE 4
LT1762 Series U W TYPICAL PERFORMANCE CHARACTERISTICS Guaranteed Dropout Voltage 450 450 400 400 350 TJ = 125°C 300 250 200 TJ = 25°C 150 = TEST POINTS 450 TJ ≤ 125°C 350 300 TJ ≤ 25°C 250 200 150 400 350 250 IL = 50mA 200 IL = 10mA 150 100 100 50 50 50 0 20 60 80 100 120 140 160 LOAD CURRENT (mA) 0 20 40 60 80 100 120 140 160 LOAD CURRENT (mA) 1762 G01 40 15 10 5 IL = 1mA 2.53 3.045 2.52 3.
PAGE 5
LT1762 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1762-2.
PAGE 6
LT1762 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1762 GND Pin Current 600 RL = 48.8Ω IL = 25mA* 500 400 RL = 122Ω IL = 10mA* 300 200 4.0 3.5 2.5 RL = 25Ω IL = 100mA* 2.0 1.5 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 LT1762-3.3 GND Pin Current 2.5 RL = 33Ω IL = 100mA* 2.0 1.5 4.0 3 4 5 6 7 INPUT VOLTAGE (V) 2 8 9 3.0 2.5 RL = 50Ω IL = 100mA* 2.0 1.5 0.9 3.0 2.5 2.0 1.5 1.0 0.5 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 2.
PAGE 7
LT1762 Series U W TYPICAL PERFORMANCE CHARACTERISTICS SHDN Pin Input Current SHDN Pin Input Current 1.4 1.6 1.2 1.4 ADJ Pin Bias Current 140 1.0 0.8 0.6 0.4 0.2 0 1 2 3 4 5 6 7 8 SHDN PIN VOLTAGE (V) 9 1.2 1.0 0.8 0.6 0.4 0 –50 –25 10 25 0 75 50 100 Current Limit 300 250 200 150 100 VIN = 7V VOUT = 0V 400 350 300 250 200 150 100 50 50 7 6 50 25 0 75 TEMPERATURE (°C) 100 1762 G31 LT1762-2.5/-3/-3.3/-5 10 LT1762 5 50 LT1762-2.5 40 LT1762-3 30 20 LT1762-3.
PAGE 8
LT1762 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1762 Minimum Input Voltage Ripple Rejection MINIMUM INPUT VOLTAGE (V) RIPPLE REJECTION (dB) 64 62 60 58 54 VIN = VOUT (NOMINAL) + 1V + 0.5VP-P RIPPLE AT f = 120Hz IL = 150mA 52 –50 –25 0 25 VOUT = 1.22V IL = 150mA 1.75 1.50 IL = 1mA 1.25 1.00 0.75 0.50 –5 –10 75 100 0 –50 –25 125 50 25 0 75 TEMPERATURE (°C) LT1762-5 OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) COUT = 10µF IL = 150mA LT1762-3.3 1 LT1762-2.5 LT1762-3 0.
PAGE 9
LT1762 Series U W TYPICAL PERFORMANCE CHARACTERISTICS LT1762-5 10Hz to 100kHz Output Noise CBYP = 100pF LT1762-5 10Hz to 100kHz Output Noise CBYP = 0 VOUT 100µV/DIV VOUT 100µV/DIV 1ms/DIV 1ms/DIV COUT = 10µF IL = 150mA COUT = 10µF IL = 150mA 1762 G44 LT1762-5 10Hz to 100kHz Output Noise CBYP = 1000pF 1762 G45 LT1762-5 10Hz to 100kHz Output Noise CBYP = 0.
PAGE 10
LT1762 Series U U U PIN FUNCTIONS OUT (Pin 1): Output. The output supplies power to the load. A minimum output capacitor of 2.2µF is required to prevent oscillations. Larger output capacitors will be required for applications with large transient loads to limit peak voltage transients. See the Applications Information section for more information on output capacitance and reverse output characteristics. SENSE (Pin 2): Output Sense. For fixed voltage versions of the LT1762 (LT1762-2.5/LT1762-3/LT1762-3.
PAGE 11
LT1762 Series U W U U APPLICATIONS INFORMATION The LT1762 series are 150mA low dropout regulators with micropower quiescent current and shutdown. The devices are capable of supplying 150mA at a dropout voltage of 270mV. Output voltage noise can be lowered to 20µVRMS over a 10Hz to 100kHz bandwidth with the addition of a 0.01µF reference bypass capacitor.
PAGE 12
LT1762 Series U W U U APPLICATIONS INFORMATION The LT1762 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 2.2µF with an ESR of 3Ω or less is recommended to prevent oscillations. The LT1762-X is a micropower device and output transient response will be a function of output capacitance.
PAGE 13
LT1762 Series U W U U APPLICATIONS INFORMATION significant enough to drop capacitor values below appropriate levels. Capacitor DC bias characteristics tend to improve as component case size increases, but expected capacitance at operating voltage should be verified. The GND pin current can be found by examining the GND Pin Current curves in the Typical Performance Characteristics. Power dissipation will be equal to the sum of the two components listed above.
PAGE 14
LT1762 Series U W U U APPLICATIONS INFORMATION where, IOUT(MAX) = 150mA VIN(MAX) = 6V IGND at (IOUT = 150mA, VIN = 6V) = 5mA So, P = 150mA(6V – 3.3V) + 5mA(6V) = 0.44W The thermal resistance will be in the range of 110°C/W to 140°C/W depending on the copper area. So the junction temperature rise above ambient will be approximately equal to: 0.
PAGE 15
LT1762 Series U W U U APPLICATIONS INFORMATION REVERSE OUTPUT CURRENT (µA) 100 TJ = 25°C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VSENSE (LT1762-2.5/LT1762-3 LT1762-3.3/LT1762-5) VOUT = VADJ (LT1762) 90 80 70 60 50 40 30 LT1762 LT1762-2.5 LT1762-3 20 LT1762-5 10 LT1762-3.3 0 0 1 2 3 4 5 6 7 8 OUTPUT VOLTAGE (V) 9 10 1762 F07 Figure 7. Reverse Output Current U PACKAGE DESCRIPTION MS8 Package 8-Lead Plastic MSOP (LTC DWG # 05-08-1660) 0.118 ± 0.004* (3.00 ± 0.102) 8 7 6 5 0.
PAGE 16
LT1762 Series U TYPICAL APPLICATION Paralleling of Regulators for Higher Output Current R1 0.1Ω + VIN > 3.7V IN OUT + FB C1 10µF C4 0.01µF LT1762-3.3 3.3V 300mA C2 10µF SHDN BYP GND R2 0.1Ω IN OUT C5 0.01µF LT1762 BYP SHDN SHDN ADJ GND R3 2.2k R4 2.2k 3 1/2 LT1490 2 R7 1.21k 8 + – R6 2k 1 R5 10k 4 1762 TA03 C3 0.01µF RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20µA IQ Includes 2.