TI’s LDO Regulator Built to Support a 2.4V to 18V Input Range with “Ultra-low” IQ

January 02, 2020 by Gary Elinoff

The TPS7A24 low-dropout linear voltage regulator from Texas Instruments comes in fixed and adjustable versions.

Texas Instruments' TPS7A24, a low-dropout (LDO) linear voltage regulator, features an “ultra-low” quiescent current (IQ)+ in the 2.0 µA range. TI explains that this feature will allow mobile devices to go longer without recharging.



The TPS7A24 low dropout (LDO) linear voltage regulator. Image (modified) used courtesy of Texas Instruments

It may also contribute to the overall energy efficiency of electronic devices.


Maximum Dropout Voltage

TI posits that the TPS7A24 LDO maximum dropout voltage is less than 250mV at 200mA of current, allowing it to operate more efficiently than standard linear regulators. 

For an LDO that provides any given output voltage, the input voltage must be somewhat larger. The dropout voltage (VDO) specifies just how much larger that input must be.  RDS(ON) is defined as the resistance from gate to source of the LDO’s pass transistor. IRATED is the maximum output current that the LDO can provide.


Typical application circuit for TPS7A24

Typical application circuit for TPS7A24. Image used courtesy of (PDF) Texas Instruments

The relevant relationship is RDS(ON) =  VDO/IRATED
Thus, if an LDO is operating at less than IRATED, the dropout voltage value goes down.


Low Quiescent Current (IQ)

The new device's maximum dropout voltage is said to allow "92.8% efficiency from a 3.55-Vinput voltage (VIN) to a 3.3-V output voltage (VOUT)."


Quiescent current vs. input voltage

Quiescent current vs. input voltage. Image used courtesy of (PDF) Texas Instruments


The unit features output voltage regulation within 2% over its temperature range. TI suggests that this device can provide for a wide range of precise voltages MCUs require. 


Adjustable and Fixed Versions

The device comes in an adjustable version and a fixed version.


Fixed Version

The fixed version’s output voltage is factory-set using internal R1 and R2 in the diagram below.


Fixed version TPS7A24

Fixed version of the TPS7A24. Image used courtesy of  (PDF) Texas Instruments

This eliminates the need for external components, saving OEMs precious board space and lowering the final BOM count. The fixed version is available covering a 1.25V to 5.5V output range.


Adjustable Version

In its adjustable version, users can choose an output pin from where an external R1 and R2 pair and can attach to GND and OUT to determine the output voltage.


Adjustable version TPS7A24

Adjustable version of the TPS7A24. Image used courtesy of  (PDF) Texas Instruments

The adjustable version can supply outputs over a user-selected range of 1.24V to 17.75V. 



Applications for this device may include:

  • Cordless power tools
  • Appliance battery packs
  • Electricity meters
  • Water meters
  • Smoke and heat detectors
  • Thermostats
  • Motion detectors 

TPS7A24 also features overcurrent, overshoot pulldown, and thermal shutdown protection. It is available in a 2.9mm by 1.6mm SOT-23 (DVB) package. The operating junction temperature range is -40°C to 125°C.


Evaluation and Support Tools

The MULTIPKGLDOEVM-823 is a universal LDO linear voltage regulator evaluation module (EVM). 



The MULTIPKGLDOEVM-823 universal LDO linear voltage regulator evaluation board. Image used courtesy of Texas Instruments


This device features footprints into which the user can solder DRB-, DRV-, DQN-, and DBV-packaged LDO regulators for evaluation.


Around the Industry

The NCP1117 series from ON Semiconductor are LDO voltage regulators that can provide output currents over 1.0 amp with a maximum dropout voltage of 1.2V at 800mA over its temperature range. Devices with fixed output voltages of 1.5V, 1.8V, 1.9V, 2.0V, 2.5V, 2.85V, 3.3V, 5.0V, and 12V are available. There is also an adjustable version for outputs ranging from 1.25V to 18.8V.

Microchip’s TC1262 features available outputs of 2.5V, 2.8V, 3.0V, 3.3V, or 5.0V. The maximum output current is 500mA and typical dropout voltage is 350mV at full load.