Automotive voltage-tracking low-dropout regulator with feedback

The Texas Instruments TPS7B4260-Q1 is a monolithic, integrated LDO voltage tracker. The device is available in an 8-pin HSOIC package. The device is designed to supply power to off-board sensors in an automotive environment. The high 300mA current rating of the device allows a single device to power multiple off-board sensors simultaneously. Because the risk of failure in cables that supply off-board power is high, the device comes with integrated protection features against fault conditions such as short to battery, reverse polarity, output short to ground, and overtemperature. The device includes a topology containing two back-to-back P-channel MOSFETs. This PMOS topology eradicates the need for an external diode that is otherwise needed to help protect against fault conditions that result in the flow of reverse current. The device is designed to handle a 45V (absolute maximum) input voltage and survive the automotive load dump transient conditions.

A reference voltage applied at the adjustable input pin (ADJ/EN) is tracked with a very tight 6mV (max) tolerance across line, load, and temperature at the FB pin. This tight tracking tolerance enables the TPS7B4260-Q1 to deliver a high-precision power-supply voltage for loads up to 300mA. The reference voltage can be directly connected to the ADJ/EN pin or scaled down to lower values with the help of an external resistor divider at the ADJ/EN pin to a minimum of 2V. The output voltage can be made equal to the voltage at the ADJ/EN pin (± the tracking tolerance) by tying the FB pin directly to the OUT pin or scaled to higher values with the help of a resistive voltage divider between the FB and the OUT pin.

The device provides an effective buffer to the reference voltage of an ADC and securely transmits this voltage (or a scaled version thereof) over a long cable to power off-board sensors. If the sensor is ratiometric and the ADC samples the output, the described features of the device help significantly improve the reliability and accuracy of the sensor measurements.

By setting the ADJ/EN input pin low, the TPS7B4260-Q1 switches to standby mode, in which the quiescent current consumption of the LDO decreases to less than 3.8µA.