LM317MQ

ACTIVE

500-mA, 40-V, adjustable linear voltage regulator for automotive applications

Product details

Output options Adjustable Output, Fixed Output Iout (max) (A) 0.5 Vin (max) (V) 40 Vin (min) (V) 3 Vout (max) (V) 37 Vout (min) (V) 1.25 Fixed output options (V) 37 Noise (µVrms) 38 Iq (typ) (mA) 3.5 Thermal resistance θJA (°C/W) 60 Rating Automotive Load capacitance (min) (µF) 0 Regulated outputs (#) 1 Accuracy (%) 2 PSRR at 100 KHz (dB) 22 Dropout voltage (Vdo) (typ) (mV) 2000 Operating temperature range (°C) -40 to 125
Output options Adjustable Output, Fixed Output Iout (max) (A) 0.5 Vin (max) (V) 40 Vin (min) (V) 3 Vout (max) (V) 37 Vout (min) (V) 1.25 Fixed output options (V) 37 Noise (µVrms) 38 Iq (typ) (mA) 3.5 Thermal resistance θJA (°C/W) 60 Rating Automotive Load capacitance (min) (µF) 0 Regulated outputs (#) 1 Accuracy (%) 2 PSRR at 100 KHz (dB) 22 Dropout voltage (Vdo) (typ) (mV) 2000 Operating temperature range (°C) -40 to 125
SOT-223 (DCY) 4 45.5 mm² 6.5 x 7
  • Output Voltage Range Adjustable
    from 1.25-V to 37-V
  • Output Current Greater Than 500-mA
  • Internal Short-Circuit Current Limiting
  • Thermal-Overload Protection
  • Output Safe-Area Compensation
  • Q Devices Meet Automotive Performance Requirements
  • Customer-Specific Configuration Control Can Be Supported for Q Devices Along With
    Major-Change Approval
  • Output Voltage Range Adjustable
    from 1.25-V to 37-V
  • Output Current Greater Than 500-mA
  • Internal Short-Circuit Current Limiting
  • Thermal-Overload Protection
  • Output Safe-Area Compensation
  • Q Devices Meet Automotive Performance Requirements
  • Customer-Specific Configuration Control Can Be Supported for Q Devices Along With
    Major-Change Approval

The LM317M is an adjustable 3-terminal positive voltage regulator capable of supplying more than 500-mA over an output-voltage range of 1.25-V to
37-V. The LM317M is exceptionally easy to use and requires only two external resistors to set the output. Furthermore, both line and load regulation are better than standard fixed regulators.

In addition to having higher performance than fixed regulators, the LM317M includes on-chip current limiting, thermal-overload protection, and safe- operating-area protection. All overload protection remains fully functional if the ADJUST terminal is disconnected.

The LM317 is a floating regulator meaning there is no device ground terminal. Quiescent current flows to the load instead of being wasted flowing to ground. Regulated output voltage of hundreds of volts is possible if the maximum input to output differential does not exceed 40-V at any time. Device can be used as a floating current source controlled by a single resistor.

Normally, no capacitors are needed unless the device is more than six inches from the input filter capacitors, in which case an input bypass capacitor of any type is needed. An optional electrolytic or tantalum output capacitor can be added to improve transient response. Ceramic output capacitors can be used but output ringing may be present on transients. The ADJUST terminal can be bypassed with any type of capacitor to achieve high ripple-rejection ratios, which are difficult to achieve with standard three-terminal regulators.

The LM317M is an adjustable 3-terminal positive voltage regulator capable of supplying more than 500-mA over an output-voltage range of 1.25-V to
37-V. The LM317M is exceptionally easy to use and requires only two external resistors to set the output. Furthermore, both line and load regulation are better than standard fixed regulators.

In addition to having higher performance than fixed regulators, the LM317M includes on-chip current limiting, thermal-overload protection, and safe- operating-area protection. All overload protection remains fully functional if the ADJUST terminal is disconnected.

The LM317 is a floating regulator meaning there is no device ground terminal. Quiescent current flows to the load instead of being wasted flowing to ground. Regulated output voltage of hundreds of volts is possible if the maximum input to output differential does not exceed 40-V at any time. Device can be used as a floating current source controlled by a single resistor.

Normally, no capacitors are needed unless the device is more than six inches from the input filter capacitors, in which case an input bypass capacitor of any type is needed. An optional electrolytic or tantalum output capacitor can be added to improve transient response. Ceramic output capacitors can be used but output ringing may be present on transients. The ADJUST terminal can be bypassed with any type of capacitor to achieve high ripple-rejection ratios, which are difficult to achieve with standard three-terminal regulators.

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Technical documentation

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* Data sheet LM317M 3-Terminal Adjustable Regulator datasheet (Rev. P) 31 Mar 2014
Application note LDO Noise Demystified (Rev. B) PDF | HTML 18 Aug 2020
Application note LDO PSRR Measurement Simplified (Rev. A) PDF | HTML 09 Aug 2017

Design & development

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Evaluation board

LM317A-337N-EVM — 3-pin adjustable regulator evaluation module

The LM317A-337N-EVM demonstrates canonical application of the LM317A adjustable regulator and its negative complement, the LM337-N. The evaluation module (EVM) is assesmbled with the SOT-223 package option for each device, supplying up to 1 A of load current. The EVM is designed for easy (...)

User guide: PDF
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SOT-223 (DCY) 4 Ultra Librarian

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