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LT1761_1中文资料

1761 G48

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(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. (20)

LT1761ES5-BYP

ORDER PART NUMBER T JMAX = 150°C, θJA = 250°C/W

SEE THE APPLICATIONS INFORMATION SECTION.

5 OUT

4 ADJ

IN 1GND 2TOP VIEW

S5 PACKAGE

5-LEAD PLASTIC SOT-23SHDN 3

5-LEAD PLASTIC SOT-23 5 OUT

4 BYP

IN 1GND 2TOP VIEW

S5 PACKAGE

5-LEAD PLASTIC SOT-23SHDN 3

Output Short-Circuit Duration......................... Indefinite Operating Junction Temperature Range

E Grade (Note 2)...............................–40°C to 125°C MP Grade (Note 2)...........................–55°C to 125°C Storage Temperature Range.................–65°C to 150°C Lead Temperature (Soldering, 10 sec)..................300°C

S5 PART MARKING 5 OUT

4 ADJ IN 1GND 2TOP VIEW

S5 PACKAGE

BYP 3

T JMAX = 150°C, θJA = 250°C/W SEE THE APPLICATIONS INFORMATION SECTION.

LT1761ES5-SD

ORDER PART NUMBER S5 PART MARKING LTGC

LTGH

LT1761ES5-1.2LT1761ES5-1.5LT1761ES5-1.8LT1761MPS5-1.8LT1761ES5-2LT1761ES5-2.5LT1761ES5-2.8LT1761ES5-3LT1761ES5-3.3LT1761ES5-5

ORDER PART NUMBER S5 PART MARKING LTCDS LTMT LTJM LTDCH LTJE LTGD LTLB LTGE LTGF LTGG

T JMAX = 150°C, θJA = 250°C/W

SEE THE APPLICATIONS INFORMATION SECTION.

ABSOLUTE AXI U RATI GS

W W W

U PACKAGE/ORDER I FOR ATIO

U U W

Consult LTC Marketing for parts specified with wider operating temperature ranges.

Order Options Tape and Reel: Add #TR

Lead Free: Add #PBF Lead Free Tape and Reel: Add #TRPBF Lead Free Part Marking: https://www.wendangku.net/doc/1c14142323.html,/leadfree/

ELECTRICAL CHARACTERISTICS

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are T A = 25°C. (Note 2) PARAMETER CONDITIONS MIN TYP MAX UNITS Load Regulation LT1761-1.2V IN = 2.3V, ΔI LOAD = 1mA to 50mA16mV

V IN = 2.3V, ΔI LOAD = 1mA to 50mA●12mV

V IN = 2.3V, ΔI LOAD = 1mA to 100mA112mV

V IN = 2.3V, ΔI LOAD = 1mA to 100mA●50mV LT1761-1.5V IN = 2.5V, ΔI LOAD = 1mA to 50mA1020mV

V IN = 2.5V, ΔI LOAD = 1mA to 50mA●35mV

V IN = 2.5V, ΔI LOAD = 1mA to 50mA1430mV

V IN = 2.5V, ΔI LOAD = 1mA to 50mA●55mV LT1761-1.8V IN = 2.8V, ΔI LOAD = 1mA to 50mA1020mV

V IN = 2.8V, ΔI LOAD = 1mA to 50mA●35mV

V IN = 2.8V, ΔI LOAD = 1mA to 100mA1530mV

V IN = 2.8V, ΔI LOAD = 1mA to 100mA●60mV LT1761-2V IN = 3V, ΔI LOAD = 1mA to 50mA1020mV

V IN = 3V, ΔI LOAD = 1mA to 50mA●35mV

V IN = 3V, ΔI LOAD = 1mA to 100mA1535mV

V IN = 3V, ΔI LOAD = 1mA to 100mA●65mV LT1761-2.5V IN = 3.5V, ΔI LOAD = 1mA to 50mA1020mV

V IN = 3.5V, ΔI LOAD = 1mA to 50mA●35mV

V IN = 3.5V, ΔI LOAD = 1mA to 100mA2040mV

V IN = 3.5V, ΔI LOAD = 1mA to 100mA●80mV LT1761-2.8V IN = 3.8V, ΔI LOAD = 1mA to 50mA1020mV

V IN = 3.8V, ΔI LOAD = 1mA to 50mA●38mV

V IN = 3.8V, ΔI LOAD = 1mA to 100mA2040mV

V IN = 3.8V, ΔI LOAD = 1mA to 100mA●86mV LT1761-3V IN = 4V, ΔI LOAD = 1mA to 50mA1020mV

V IN = 4V, ΔI LOAD = 1mA to 50mA●40mV

V IN = 4V, ΔI LOAD = 1mA to 100mA2040mV

V IN = 4V, ΔI LOAD = 1mA to 100mA●90mV LT1761-3.3V IN = 4.3V, ΔI LOAD = 1mA to 50mA1020mV

V IN = 4.3V, ΔI LOAD = 1mA to 50mA●40mV

V IN = 4.3V, ΔI LOAD = 1mA to 100mA2040mV

V IN = 4.3V, ΔI LOAD = 1mA to 100mA●100mV LT1761-5V IN = 6V, ΔI LOAD = 1mA to 50mA1530mV

V IN = 6V, ΔI LOAD = 1mA to 50mA●60mV

V IN = 6V, ΔI LOAD = 1mA to 100mA2565mV

V IN = 6V, ΔI LOAD = 1mA to 100mA●150mV LT1761 (Note 3)V IN = 2.3V, ΔI LOAD = 1mA to 50mA16mV

V IN = 2.3V, ΔI LOAD = 1mA to 50mA●12mV

V IN = 2.3V, ΔI LOAD = 1mA to 100mA112mV

V IN = 2.3V, ΔI LOAD = 1mA to 100mA●50mV Dropout Voltage I LOAD = 1mA0.100.15V V IN = V OUT(NOMINAL)I LOAD = 1mA●0.19V (Notes 5, 6, 11)I LOAD = 10mA0.170.22V

I LOAD = 10mA●0.29V

I LOAD = 50mA0.240.28V

I LOAD = 50mA●0.38V

I LOAD = 100mA0.300.35V

I LOAD = 100mA●0.45V

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PARAMETER CONDITIONS MIN TYP MAX UNITS GND Pin Current I LOAD = 0mA ●2045μA V IN = V OUT(NOMINAL)I LOAD = 1mA ●55100μA (Notes 5, 7)

I LOAD = 10mA ●230400μA I LOAD = 50mA ●12mA I LOAD = 100mA

●

2.24mA Output Voltage Noise C OUT = 10μF, C BYP = 0.01μF, I LOAD = 100mA, BW = 10Hz to 100kHz 20μV RMS

ADJ Pin Bias Current (Notes 3, 8)30

100nA Shutdown Threshold V OUT = Off to On ●0.82V V OUT = On to Off ●0.25

0.65V SHDN Pin Current V SHDN = 0V ●00.5μA (Note 9)

V SHDN = 20V ●13μA Quiescent Current in Shutdown V IN = 6V, V SHDN = 0V

0.01

0.1

μA Ripple Rejection (Note 3)V IN – V OUT = 1.5V (Avg), V RIPPLE = 0.5V P-P , f RIPPLE = 120Hz,5565dB I LOAD = 50mA

Current Limit

V IN = 7V, V OUT = 0V

200

mA V IN = V OUT(NOMINAL) + 1V or 2.3V (Note 12), ΔV OUT = –5%●110

Input Reverse Leakage Current V IN = –20V, V OUT = 0V

●1

mA Reverse Output Current LT1761-1.2V OUT = 1.2V, V IN < 1.2V 1020μA (Note 10)

LT1761-1.5V OUT = 1.5V, V IN < 1.5V 1020μA LT1761-1.8V OUT = 1.8V, V IN < 1.8V 1020μA LT1761-2V OUT = 2V, V IN < 2V 1020μA LT1761-2.5V OUT = 2.5V, V IN < 2.5V 1020μA LT1761-2.8V OUT = 2.8V, V IN < 2.8V 1020μA LT1761-3V OUT = 3V, V IN < 3V 1020μA LT1761-3.3V OUT = 3.3V, V IN < 3.3V 1020μA LT1761-5V OUT = 5V, V IN < 5V

1020μA LT1761 (Note 3)V OUT = 1.22V, V IN < 1.22V

μA

Note 1: Stresses beyond those listed under Absolute Maximum Ratings may cause permanent damage to the device. Exposure to any Absolute Maximum Rating condition for extended periods may affect device reliability and lifetime.

Note 2: The LT1761 regulators are tested and specified under pulse load conditions such that T J ≈ T A . The LT1761E is 100% production tested at T A = 25°C. Performance at –40°C and 125°C is assured by design,characterization and correlation with statistical process controls. The LT1761MP is 100% tested and guaranteed over the –55°C to 125°C temperature range.

Note 3: The LT1761 (adjustable versions) are tested and specified for these conditions with the ADJ pin connected to the OUT pin.Note 4: Operating conditions are limited by maximum junction

temperature. The regulated output voltage specification will not apply for all possible combinations of input voltage and output current. When operating at maximum input voltage, the output current range must be limited. When operating at maximum output current, the input voltage range must be limited.

Note 5: To satisfy requirements for minimum input voltage, the LT1761(adjustable version) is tested and specified for these conditions with an external resistor divider (two 250k resistors) for an output voltage of 2.44V. The external resistor divider will add a 5μA DC load on the output.

ELECTRICAL CHARACTERISTICS

Note 6: Dropout voltage is the minimum input to output voltage differential needed to maintain regulation at a specified output current. In dropout, the output voltage will be equal to: V IN – V DROPOUT .

Note 7: GND pin current is tested with V IN = V OUT(NOMINAL) or V IN = 2.3V (whichever is greater) and a current source load. This means the device is tested while operating in its dropout region or at the minimum input

voltage specification. This is the worst-case GND pin current. The GND pin current will decrease slightly at higher input voltages.Note 8: ADJ pin bias current flows into the ADJ pin.Note 9: SHDN pin current flows into the SHDN pin.

Note 10: Reverse output current is tested with the IN pin grounded and the OUT pin forced to the rated output voltage. This current flows into the OUT pin and out the GND pin.

Note 11: For the LT1761, LT1761-1.2, LT1761-1.5, LT1761-1.8 and LT1761-2 dropout voltage will be limited by the minimum input voltage specification under some output voltage/load conditions. See the curve of Minimum Input Voltage in the Typical Performance Characteristics.

Note 12: To satisfy requirements for minimum input voltage, current limit is tested at V IN = V OUT(NOMINAL) + 1V or V IN = 2.3V, whichever is greater.

The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are T A = 25°C. (Note 2)

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function if the SHDN pin is not connected. For the LT1761-BYP, the SHDN pin is internally connected to V IN .BYP (Pins 3/4, Fixed/-BYP Devices): Bypass. The BYP pin is used to bypass the reference of the LT1761 regula-tors to achieve low noise performance from the regulator.The BYP pin is clamped internally to ±0.6V (one V BE ) from ground. A small capacitor from the output to this pin will bypass the reference to lower the output voltage noise. A maximum value of 0.01μF can be used for reducing output voltage noise to a typical 20μV RMS over a 10Hz to 100kHz bandwidth. If not used, this pin must be left unconnected.ADJ (Pin 4, Adjustable Devices Only): Adjust Pin. For the adjustable LT1761, this is the input to the error amplifier.This pin is internally clamped to ±7V. It has a bias current of 30nA which flows into the pin (see curve of ADJ Pin Bias Current vs Temperature in the Typical Performance Char-acteristics section). The ADJ pin voltage is 1.22V referenced to ground and the output voltage range is 1.22V to 20V.OUT (Pin 5): Output. The output supplies power to the load. A minimum output capacitor of 1μF 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.

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. The LT1761 regulators are designed to withstand reverse voltages on the IN pin with respect to ground and the OUT pin. In the case of a reverse input, which can happen if a battery is plugged in backwards, the device will act as if there is a diode in series with its input. There will be no reverse current flow into the regulator and no reverse voltage will appear at the load. The device will protect both itself and the load.GND (Pin 2): Ground.

SHDN (Pin 3, Fixed/-SD Devices): Shutdown. The SHDN pin is used to put the LT1761 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 1μA. If unused, the SHDN pin must be connected to V IN . The device will not

U U U

PI FU CTIO S

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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. The resulting voltages produced can cause appreciable amounts of noise, especially when a ceramic capacitor is used for noise bypassing. A ceramic capaci-tor produced Figure 5’s trace in response to light tapping from a pencil. Similar vibration induced behavior can masquerade as increased output voltage noise.Thermal Considerations

The power handling capability of the device will be limited by the maximum rated junction temperature (125°C). The power dissipated by the device will be made up of two components:

1.Output current multiplied by the input/output voltage differential: (I OUT )(V IN – V OUT ), and

2.GND pin current multiplied by the input voltage:(I GND )(V IN ).The ground pin current can be found by examining the GND Pin Current curves in the Typical Performance Char-acteristics section. Power dissipation will be equal to the sum of the two components listed above.

APPLICATIO N S I N FOR M ATIO N

W U

U U The LT1761 series regulators have internal thermal limit-ing designed to protect the device during overload condi-tions. For continuous normal conditions, the maximum junction temperature rating of 125°C must not be exceeded. It is important to give careful consideration to 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. Copper board stiffeners and plated through-holes can also be used to spread the heat gener-ated by power devices.

The following table lists thermal resistance for several different board sizes and copper areas. All measurements were taken in still air on 3/32" FR-4 board with one ounce copper.

Table 1. Measured Thermal Resistance

COPPER AREA THERMAL RESISTANCE TOPSIDE*BACKSIDE BOARD AREA (JUNCTION-TO-AMBIENT)

2500mm 22500mm 22500mm 2125°C/W 1000mm

2500mm

125°C/W 225mm 22500mm 22500mm 2130°C/W 100mm 22500mm 22500mm 2135°C/W 50mm 2

2500mm 2

150°C/W

*Device is mounted on topside.

100ms/DIV 1761 F05

V OUT 500μV/DIV

Figure 5. Noise Resulting from Tapping on a Ceramic Capacitor

LT1761-5

C OUT = 10μF C BYP = 0.01μF I LOA

D = 100mA

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Calculating Junction Temperature

Example: Given an output voltage of 3.3V, an input voltage range of 4V to 6V, an output current range of 0mA to 50mA 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:I OUT(MAX)(V IN(MAX) – V OUT ) + I GND (V IN(MAX))where,

I OUT(MAX) = 50mA V IN(MAX) = 6V

I GND at (I OUT = 50mA, V IN = 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. So the junction temperature rise above ambient will be approximately equal to:

0.14W(150°C/W) = 21.2°C

The maximum junction temperature will then be equal to the maximum junction temperature rise above ambient plus the maximum ambient temperature or:T JMAX = 50°C + 21.2°C = 71.2°C

Protection Features

The LT1761 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.

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 opera-tion, the junction temperature should not exceed 125°C.The input of the device will withstand reverse voltages of 20V. 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. The device will protect both itself and the load. This provides protection against batteries which can be plugged in backward.

The output of the LT1761-X can be pulled below ground without damaging the device. If the input is left open circuit or grounded, the output can be pulled below ground by 20V. For fixed voltage versions, the output will act like a large resistor, typically 500k Ω or higher, limiting current flow to typically less than 100μA. For adjustable versions, the output will act like an open circuit; no current will flow out of the pin. If the input is powered by a voltage source, the output will source the short-circuit current of the device and will protect itself by thermal limiting. In this case, grounding the SHDN pin will turn off the device and stop the output from sourcing the short-circuit current.

The ADJ pin of the adjustable device can be pulled above or below ground by as much as 7V without damaging the device. If the input is left open circuit or grounded, the ADJ pin will act like an open circuit when pulled below ground and like a large resistor (typically 100k) in series with a diode when pulled above ground.

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

APPLICATIO S I FOR ATIO

W U

Information furnished by Linear Technology C orporation is believed to be accurate and reliable. However, no responsibility is assumed for its use. Linear Technology Corporation makes no represen-tation that the interconnection of circuits as described herein will not infringe on existing patent rights.19

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LT 0507 REV C ? PRINTED IN USA

? LINEAR TECHNOLOGY CORPORA TION 2005

Linear Technology Corporation

1630 McCarthy Blvd., Milpitas, CA 95035-7417

(408) 432-1900 ● FAX: (408) 434-0507 ● https://www.wendangku.net/doc/1c14142323.html,

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