Datasheet

ManualsBrandsLinear Technology ManualsIntegrated Circuits (ICs)LDO Voltage Regulator, 1.2 ... 20V, TO-263-5

LT1764A Series

1764afb

3A, Fast Transient

Response, Low Noise,

LDO Regulators

■

Optimized for Fast Transient Response

■

Output Current: 3A

■

Dropout Voltage: 340mV at 3A

■

Low Noise: 40

RMS

(10Hz to 100kHz)

■

1mA Quiescent Current

■

Wide Input Voltage Range: 2.7V to 20V

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No Protection Diodes Needed

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Controlled Quiescent Current in Dropout

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Fixed Output Voltages: 1.5V, 1.8V, 2.5V, 3.3V

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Adjustable Output from 1.21V to 20V

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<1µA Quiescent Current in Shutdown

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Stable with 10µF Output Capacitor*

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Stable with Ceramic Capacitors*

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Reverse Battery Protection

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No Reverse Current

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Thermal Limiting

The LT

1764A is a low dropout regulator optimized for

fast transient response. The device is capable of supplying

3A of output current with a dropout voltage of 340mV.

Operating quiescent current is 1mA, dropping to <1µA in

shutdown. Quiescent current is well controlled; it does not

rise in dropout as it does with many other regulators. In

addition to fast transient response, the LT1764A has very

low output voltage noise which makes the device ideal for

sensitive RF supply applications.

Output voltage range is from 1.21V to 20V. The LT1764A

regulators are stable with output capacitors as low as 10µF.

Internal protection circuitry includes reverse battery pro-

tection, current limiting, thermal limiting and reverse cur-

rent protection. The device is available in fixed output

voltages of 1.5V, 1.8V, 2.5V, 3.3V and as an adjustable

device with a 1.21V reference voltage. The LT1764A regu-

lators are available in 5-lead TO-220 and DD packages, and

16-lead FE packages.

Dropout Voltage

3.3V

to 2.5V

OUT

Regulator

■

3.3V to 2.5V Logic Power Supply

■

Post Regulator for Switching Supplies

FEATURES

DESCRIPTIO

APPLICATIO S

TYPICAL APPLICATIO

SHDN

10µF*

*TANTALUM,

CERAMIC OR

ALUMINUM ELECTROLYTIC

1764 TA01

OUT

> 3V

SENSE

GND

LT1764A-2.5

2.5V

10µF*

LOAD CURRENT (A)

0 0.5

DROPOUT VOLTAGE (mV)

1.0 2.01.5

2.5

3.0

1764 TA02

400

350

300

250

200

150

100

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

All other trademarks are the property of their respective owners.

*See Applications Information Section.

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Summary of content (20 pages)

PAGE 1
LT1764A Series 3A, Fast Transient Response, Low Noise, LDO Regulators U FEATURES DESCRIPTIO ■ The LT ®1764A is a low dropout regulator optimized for fast transient response. The device is capable of supplying 3A of output current with a dropout voltage of 340mV. Operating quiescent current is 1mA, dropping to < 1µA in shutdown. Quiescent current is well controlled; it does not rise in dropout as it does with many other regulators.
PAGE 2
LT1764A Series W W U W ABSOLUTE MAXIMUM RATINGS (Note 1) IN Pin Voltage ........................................................ ±20V OUT Pin Voltage .................................................... ±20V Input to Output Differential Voltage (Note 12) ....... ±20V SENSE Pin Voltage ............................................... ±20V ADJ Pin Voltage ...................................................... ±7V SHDN Pin Voltage .................................................
PAGE 3
LT1764A Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS LT1764A-2.5 VIN = 3V, ILOAD = 1mA 3.5V < VIN < 20V, 1mA < ILOAD < 3A ● 2.462 2.412 2.500 2.500 2.538 2.575 V V LT1764A-3.3 VIN = 3.8V, ILOAD = 1mA 4.3V < VIN < 20V, 1mA < ILOAD < 3A ● 3.250 3.183 3.300 3.300 3.350 3.400 V V ● ● 1.192 1.168 1.168 1.210 1.210 1.210 1.228 1.
PAGE 4
LT1764A Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS Current Limit MIN TYP VIN = 7V, VOUT = 0V Input Reverse Leakage Current MAX UNITS 4 A E Grade: LT1764A; LT1764A-1.5; VIN = 2.7V, ∆VOUT = – 0.1V ● 3.1 A MP Grade: LT1764A VIN = 2.8V, ∆VOUT = – 0.1V ● 3.1 A VIN = – 20V, VOUT = 0V ● Reverse Output Current (Note 10) LT1764A-1.5 VOUT = 1.
PAGE 5
LT1764A Series U W TYPICAL PERFOR A CE CHARACTERISTICS Quiescent Current LT1764A-1.5 Output Voltage LT1764A-1.8 Output Voltage 1.54 1.4 1.84 IL = 1mA IL = 1mA 1.0 LT1764A 0.8 0.6 0.4 VIN = 6V RL = ∞ IL = 0 VSHDN = VIN 0.2 0 –50 –25 1.53 1.83 1.52 1.82 OUTPUT VOLTAGE (V) QUIESCENT CURRENT (mA) 1.2 OUTPUT VOLTAGE (V) LT1764A-1.5/1.8/2.5/3.3 1.51 1.50 1.49 1.48 1.47 50 25 75 0 TEMPERATURE (°C) 100 0 50 75 25 TEMPERATURE (°C) 100 1764 G04 1.76 – 50 – 25 125 IL = 1mA IL = 1mA 2.
PAGE 6
LT1764A Series U W TYPICAL PERFOR A CE CHARACTERISTICS LT1764A-3.3 Quiescent Current 20 15 10 20.0 TJ = 25°C 1.4 RL = 4.3k VSHDN = VIN 1.2 17.5 GND PIN CURRENT (mA) 25 1.6 1.0 0.8 0.6 0.4 0.2 5 0 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 2 4 LT1764A-1.8 GND Pin Current 5.0 RL = 18Ω IL = 100mA* TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 30 RL = 5Ω IL = 500mA* 25 20 RL = 25Ω IL = 100mA* 15 RL = 8.
PAGE 7
LT1764A Series U W TYPICAL PERFOR A CE CHARACTERISTICS LT1764A-2.5 GND Pin Current TJ = 25°C VSHDN = VIN *FOR VOUT = 2.5V RL = 0.83Ω IL = 3A* 120 80 RL = 1.66Ω IL = 1.5A* 40 0 1 0 2 RL = 3.57Ω IL = 0.7A* 3 4 5 6 7 INPUT VOLTAGE (V) 120 80 RL = 2.2Ω IL = 1.5A* RL = 4.71Ω IL = 0.7A* 9 0 10 0 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 1.0 0.9 100 80 60 40 20 10 1.0 2.0 1.5 OUTPUT CURRENT (A) 2.5 0.5 0.4 0.3 0.
PAGE 8
LT1764A Series U W TYPICAL PERFOR A CE CHARACTERISTICS Current Limit 6 Reverse Output Current 6 5 VIN = 7V VOUT = 0V 5 CURRENT LIMIT (A) CURRENT LIMIT (A) TJ = –50°C 4 TJ = 125°C 3 TJ = 25°C 2 1 4 3 2 1 5.0 LT1764A-1.5 REVERSE OUTPUT CURRENT (mA) Current Limit 4.5 LT1764A-1.8 4.0 LT1764A-2.5 3.5 3.0 LT1764A-3.3 LT1764A 2.5 TJ = 25°C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT1764A) VOUT = VFB (LT1764A-1.5/1.8/-2.5/-3.3) 2.0 1.5 1.0 0.
PAGE 9
LT1764A Series U W TYPICAL PERFOR A CE CHARACTERISTICS RMS Output Noise vs Load Current (10Hz to 100kHz) 40 COUT = 10µF LT1764A-3.3 10Hz to 100kHz Output Noise LT1764A-3.3 OUTPUT NOISE (µVRMS) 35 30 LT1764A-2.5 25 VOUT 100µV/DIV LT1764A-1.8 20 15 LT1764A-1.5 LT1764A 10 COUT = 10µF IL = 3A 5 0 0.0001 0.001 0.01 0.1 LOAD CURRENT (A) 1ms/DIV 1764A G37 10 1 1764 G36 0.1 0 VIN = 4.3V CIN = 3.3µF TANTALUM COUT = 10µF TANTALUM –0.1 –0.2 OUTPUT VOLTAGE DEVIATION (V) 0.2 LT1764A-3.
PAGE 10
LT1764A Series U U U PI FU CTIO S DD/TO-220/TSSOP SHDN (Pin 1/1/10): Shutdown. The SHDN pin is used to put the LT1764A regulators into a low power shutdown state. The output will be off when the SHDN pin is pulled low. The SHDN pin can be driven either by 5V logic or open-collector logic with a pull-up resistor. The pull-up resistor is required to supply the pull-up current of the open-collector gate, normally several microamperes, and the SHDN pin current, typically 7µA.
PAGE 11
LT1764A Series U W U U APPLICATIO S I FOR ATIO The LT1764A series are 3A low dropout regulators optimized for fast transient response. The devices are capable of supplying 3A at a dropout voltage of 340mV. The low operating quiescent current (1mA) drops to less than 1µA in shutdown. In addition to the low quiescent current, the LT1764A regulators incorporate several protection features which make them ideal for use in battery-powered systems.
PAGE 12
LT1764A Series U W U U APPLICATIO S I FOR ATIO ing the capacitor value improves the stability and reduces the ringing. Table 1 gives some recommended values of ESR to minimize ringing caused by fast, hard current transitions. Table 1. Capacitor Minimum ESR VOUT 10µF 22µF 47µF 100µF 1.2V 10mΩ 5mΩ 3mΩ 0mΩ 1.5V 7mΩ 5mΩ 3mΩ 0mΩ 1.8V 5mΩ 5mΩ 3mΩ 0mΩ 2.5V 0mΩ 0mΩ 0mΩ 0mΩ 3.
PAGE 13
LT1764A Series VOUT = 1.2V IOUT = 1A WITH 1A PULSE COUT = 10µF CERAMIC 10 5 20mV/DIV 50mV/DIV RESR (mΩ) 5 VOUT = 1.2V IOUT = 1A WITH 1A PULSE COUT = 100µF CERAMIC 0 RESR (mΩ) 0 10 20 20 50 20µs/DIV 20µs/DIV 1764A F03 Figure 6 Figure 3 VOUT = 2.5V IOUT = 1A WITH 1A PULSE COUT = 10µF CERAMIC 5 5 20mV/DIV 50mV/DIV 10 VOUT = 2.
PAGE 14
LT1764A Series U U W U APPLICATIONS INFORMATION Ceramic Capacitors Extra consideration must be given to the use of ceramic capacitors. Ceramic capacitors are manufactured with a variety of dielectrics, each with different behavior over temperature and applied voltage. The most common dielectrics used are Z5U, Y5V, X5R and X7R. The Z5U and Y5V dielectrics are good for providing high capacitances in a small package, but exhibit strong voltage and temperature coefficients as shown in Figures 3 and 4.
PAGE 15
LT1764A Series U W U U APPLICATIONS INFORMATION is no DC current in the output capacitor. Worst case ripple current will occur if the output load is a high frequency (>100kHz) square wave with a high peak value and fast edges (< 1µs). Measured RMS value for this case is 0.5 times the peak-to-peak current change. Slower edges or lower frequency will significantly reduce the RMS ripple current in the capacitor.
PAGE 16
LT1764A Series U U W U APPLICATIONS INFORMATION all sources of thermal resistance from junction to ambient. Additional heat sources mounted nearby must also be considered. For surface mount devices, heat sinking is accomplished by using the heat spreading capabilities of the PC board and its copper traces. Surface mount heatsinks and plated through-holes can also be used to spread the heat generated by power devices.
PAGE 17
LT1764A Series U U W U APPLICATIONS INFORMATION will typically drop to less than 2µA. This can happen if the input of the device is connected to a discharged (low voltage) battery and the output is held up by either a backup battery or a second regulator circuit. The state of the SHDN pin will have no effect on the reverse output current when the output is pulled above the input.
PAGE 18
LT1764A Series U TYPICAL APPLICATIO S Adjustable Current Source R5 0.01Ω + VIN > 2.7V C1 10µF LT1004-1.2 IN OUT LT1764A-1.8 SHDN FB R1 1k R2 40.2k R4 2.2k R6 2.2k LOAD R8 100k GND R3 2k C3 1µF R7 470Ω ADJUST R1 FOR 0A TO 3A CONSTANT CURRENT 2 – 3 + 8 1/2 LT1366 1 4 C2 3.3µF 1764 TA04 U PACKAGE DESCRIPTION Q Package 5-Lead Plastic DD Pak (Reference LTC DWG # 05-08-1461) 0.256 (6.502) 0.060 (1.524) 0.060 (1.524) TYP 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.
PAGE 19
LT1764A Series U PACKAGE DESCRIPTION T Package 5-Lead Plastic TO-220 (Standard) (Reference LTC DWG # 05-08-1421) 0.147 – 0.155 (3.734 – 3.937) DIA 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.572) 0.045 – 0.055 (1.143 – 1.397) 0.230 – 0.270 (5.842 – 6.858) 0.570 – 0.620 (14.478 – 15.748) 0.460 – 0.500 (11.684 – 12.700) 0.620 (15.75) TYP 0.330 – 0.370 (8.382 – 9.398) 0.700 – 0.728 (17.78 – 18.491) 0.095 – 0.115 (2.413 – 2.921) SEATING PLANE 0.260 – 0.320 (6.60 – 8.13) 0.067 BSC (1.
PAGE 20
LT1764A Series U TYPICAL APPLICATIO Paralleling of Regulators for Higher Output Current R1 0.01Ω + IN OUT LT1764A-3.3 SHDN FB C1 100µF VIN > 3.7V + 3.3V 6A C2 22µF GND R2 0.01Ω IN SHDN OUT LT1764A SHDN ADJ R7 4.12k GND R3 2.2k R4 2.2k 3 + 8 – 4 R5 1k 1 1/2 LT1366 2 R6 6.65k C3 0.01µF 1764 TA05 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20µA IQ Includes 2.