Datasheet

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LT1764 Series

1764fb

3A, Fast Transient

Response, Low Noise,

LDO Regulators

■

Optimized for Fast Transient Response

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Output Current: 3A

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Dropout Voltage: 340mV at 3A

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Low Noise: 40

RMS

(10Hz to 100kHz)

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1mA Quiescent Current

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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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Reverse Battery Protection

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No Reverse Current

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Thermal Limiting

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Available in 5-Lead TO-220, DD and 16-Lead

TSSOP Packages

The LT

1764 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. Oper-

ating 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 LT1764 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 LT1764

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 LT1764 regu-

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

16-lead TSSOP 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

1764 TA01

OUT

> 3V

SENSE

GND

LT1764-2.5

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

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

All other trademarks are the property of their respective owners. Protected by U.S. Patents,

including 6144250, 6118263.

Summary of content (20 pages)

PAGE 1
LT1764 Series 3A, Fast Transient Response, Low Noise, LDO Regulators U FEATURES DESCRIPTIO ■ The LT ®1764 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
LT1764 Series U W W 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
LT1764 Series ELECTRICAL CHARACTERISTICS The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are TA = 25°C. (Note 2) PARAMETER CONDITIONS Minimum Input Voltage (Notes 3, 11) ILOAD = 0.5A ILOAD = 1.5A ILOAD = 2.7A, 110°C < TJ ≤ 125°C ILOAD = 3A, – 40°C ≤ TJ ≤ 110°C Regulated Output Voltage (Note 4) MIN TYP MAX UNITS 1.7 1.9 2.3 2.3 2.7 2.7 V V V V LT1764-1.5 VIN = 2.21V, ILOAD = 1mA 2.
PAGE 4
LT1764 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 GND Pin Current VIN = VOUT(NOMINAL) + 1V (Notes 5, 7) ILOAD = 0mA ILOAD = 1mA ILOAD = 100mA ILOAD = 500mA ILOAD = 1.5A ILOAD = 2.
PAGE 5
LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS Typical Dropout Voltage Guaranteed Dropout Voltage GUARANTEED DROPOUT VOLTAGE (mV) 700 DROPOUT VOLTAGE (mV) 500 400 TJ = 125°C 300 200 TJ = 25°C 100 0 0 0.5 1.0 1.5 2.0 OUTPUT CURRENT (A) 2.5 = TEST POINTS 600 500 500 TJ ≤ 125°C 400 300 TJ ≤ 25°C 200 0 Quiescent Current LT1764 0.8 0.6 VIN = 6V RL = ∞ IL = 0 VSHDN = VIN 50 25 75 0 TEMPERATURE (°C) 0.5 2.0 1.5 1.0 OUTPUT CURRENT (A) IL = 1mA 2.56 1.82 2.54 1.81 1.80 1.79 1.78 3.
PAGE 6
LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS LT1764-2.5 Quiescent Current LT1764-3.3 Quiescent Current TJ = 25°C RL = ∞ VSHDN = VIN 1.6 TJ = 25°C RL = ∞ VSHDN = VIN 35 QUIESCENT CURRENT (mA) 30 25 20 15 10 5 30 25 20 15 10 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 10 0 1 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 1764 G10 LT1764-1.8 GND Pin Current 0 RL = 6Ω IL = 300mA* 7.5 5.0 RL = 18Ω IL = 100mA* 2.5 2 3 4 5 6 7 INPUT VOLTAGE (V) 8 9 TJ = 25°C VSHDN = VIN *FOR VOUT = 2.
PAGE 7
LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS 200 150 TJ = 25°C VSHDN = VIN *FOR VOUT = 3.3V RL = 1.1Ω IL = 3A* 120 80 RL = 2.2Ω IL = 1.5A* RL = 4.71Ω IL = 0.7A* 40 GND Pin Current vs ILOAD 160 TJ = 25°C VSHDN = VIN *FOR VOUT = 1.21V 120 GND PIN CURRENT (mA) 160 GND PIN CURRENT (mA) LT1764 GND Pin Current RL = 0.4Ω IL = 3A* 90 RL = 0.81Ω IL = 1.5A* 60 RL = 1.73Ω IL = 0.7A* VIN = VOUT(NOM) + 1V 140 GND PIN CURRENT (mA) LT1764-3.
PAGE 8
LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS Current Limit Reverse Output Current VIN = 7V VOUT = 0V CURRENT LIMIT (A) 5 4 3 2 1 5.0 REVERSE OUTPUT CURRENT (mA) 6 4.5 LT1764 4.0 LT1764-1.8 3.5 3.0 LT1764-2.5 LT1764-3.3 2.5 TJ = 25°C VIN = 0V CURRENT FLOWS INTO OUTPUT PIN VOUT = VADJ (LT1764) VOUT = VFB (LT1764-1.8/-2.5/-3.3) 2.0 1.5 1.0 0.
PAGE 9
LT1764 Series U W TYPICAL PERFOR A CE CHARACTERISTICS Load Regulation Output Noise Spectral Density OUTPUT NOISE SPECTRAL DENSITY (µV/√Hz) 10 LOAD REGULATION (mV) 5 LT1764 0 –5 LT1764-1.8 –10 LT1764-2.5 –15 LT1764-3.3 –20 ∆IL = 1mA TO 3A VIN = 2.7V (LT1764) VIN = VOUT(NOM) + 1V (LT1764-1.8/-2.5/-3.3) –25 –30 – 50 – 25 75 50 25 TEMPERATURE (°C) 100 0 125 1 COUT = 10µF ILOAD = 3A LT1764-3.3 LT1764-2.5 LT1764 LT1764-1.8 0.1 0.
PAGE 10
LT1764 Series U U U PI FU CTIO S (DD and TO-220/TSSOP) SHDN (Pin 1/Pin 10): Shutdown. The SHDN pin is used to put the LT1764 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
LT1764 Series U W U U APPLICATIO S I FOR ATIO The LT1764 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 LT1764 regulators incorporate several protection features which make them ideal for use in battery-powered systems.
PAGE 12
LT1764 Series U W U U APPLICATIO S I FOR ATIO 20 The protection is designed to provide some output current at all values of input-to-output voltage up to the device breakdown. BOTH CAPACITORS ARE 16V, 1210 CASE SIZE, 10µF 0 CHANGE IN VALUE (%) X5R –20 –40 –60 Y5V –80 –100 0 2 14 8 6 4 10 12 DC BIAS VOLTAGE (V) 16 1764 F03 Figure 3. Ceramic Capacitor DC Bias Characteristics The problem occurs with a heavy output load when the input voltage is high and the output voltage is low.
PAGE 13
LT1764 Series U U W U APPLICATIONS INFORMATION Table 2. FE Package, 16-Lead TSSOP Thermal Considerations The power handling capability of the device is limited by the maximum rated junction temperature (125°C). The power dissipated by the device is made up of two components: COPPER AREA TOPSIDE* BACKSIDE BOARD AREA THERMAL RESISTANCE (JUNCTION-TO-AMBIENT) 2500mm2 2500mm2 2500mm2 38°C/W 2 2 2 43°C/W 2500mm 2 2500mm 48°C/W 2500mm2 2500mm2 60°C/W 1000mm 225mm 2 2500mm 2 2500mm 1.
PAGE 14
LT1764 Series U W U U APPLICATIONS INFORMATION Protection Features The LT1764 regulators incorporate several protection features which make them ideal for use in battery-powered circuits. In addition to the normal protection features associated with monolithic regulators, such as current limiting and thermal limiting, the devices are protected against reverse input voltages, reverse output voltages and reverse voltages from output to input.
PAGE 15
LT1764 Series U TYPICAL APPLICATIO S SCR Preregulator Provides Efficiency Over Line Variations L1 500µH NTE5437 LT1764-3.3 L2 90V AC TO 140V AC + 1N4148 10V AC AT 115VIN IN SHDN 10000µF OUT FB 22µF GND 1k VOUT 3.3V 3A + 34k* 10V AC AT 115VIN 12.1k* NTE5437 1N4002 1N4002 V+ “SYNC” 1N4002 TO ALL “V +” POINTS 2.4k + + 22µF 750Ω 1N4148 200k C1A 1/2 LT1018 0.1µF – V+ 0.
PAGE 16
LT1764 Series U TYPICAL APPLICATIO S Adjustable Current Source R5 0.01Ω + VIN > 2.7V C1 10µF LT1004-1.2 IN OUT LT1764-1.8 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 C2 3.
PAGE 17
LT1764 Series U 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 18
LT1764 Series U PACKAGE DESCRIPTION T Package 5-Lead Plastic TO-220 (Standard) (LTC DWG # 05-08-1421) 0.390 – 0.415 (9.906 – 10.541) 0.165 – 0.180 (4.191 – 4.572) 0.147 – 0.155 (3.734 – 3.937) DIA 0.045 – 0.055 (1.143 – 1.397) 0.230 – 0.270 (5.842 – 6.858) 0.460 – 0.500 (11.684 – 12.700) 0.570 – 0.620 (14.478 – 15.748) 0.330 – 0.370 (8.382 – 9.398) 0.620 (15.75) TYP 0.700 – 0.728 (17.78 – 18.491) SEATING PLANE 0.152 – 0.202 0.260 – 0.320 (3.861 – 5.131) (6.60 – 8.13) 0.095 – 0.115 (2.413 – 2.
PAGE 19
LT1764 Series U PACKAGE DESCRIPTION FE Package 16-Lead Plastic TSSOP (4.4mm) (Reference LTC DWG # 05-08-1663) Exposed Pad Variation BB 4.90 – 5.10* (.193 – .201) 3.58 (.141) 3.58 (.141) 16 1514 13 12 1110 6.60 ±0.10 9 2.94 (.116) 4.50 ±0.10 2.94 6.40 (.116) (.252) BSC SEE NOTE 4 0.45 ±0.05 1.05 ±0.10 0.65 BSC 1 2 3 4 5 6 7 8 RECOMMENDED SOLDER PAD LAYOUT 4.30 – 4.50* (.169 – .177) 0.09 – 0.20 (.0035 – .0079) 0.50 – 0.75 (.020 – .030) NOTE: 1.
PAGE 20
LT1764 Series U TYPICAL APPLICATIO Paralleling of Regulators for Higher Output Current R1 0.01Ω + IN OUT LT1764-3.3 SHDN FB C1 100µF VIN > 3.7V + 3.3V 6A C2 22µF GND R2 0.01Ω IN SHDN OUT LT1764 SHDN R7 4.12k GND R3 2.2k R4 2.2k 3 + 8 – 4 R5 1k 1 1/2 LT1366 2 R6 6.65k ADJ C3 0.01µF 1764 TA05 RELATED PARTS PART NUMBER DESCRIPTION COMMENTS LT1120 125mA Low Dropout Regulator with 20µA IQ Includes 2.