Automotive 300mA 40V voltage-tracking low-dropout regulator with feedback and 6mV tracking tolerance

The TPS7B4260-Q1 is a monolithic, integrated, low-dropout (LDO) voltage

tracker. The device is available in an 8-pin HSOIC package. The TPS7B4260-Q1 is designed to reliably provide power to

off-board sensors with a wire harness, even in harsh automotive environments. In

such severe operating conditions, the cables in the harness are potentially exposed

to various fault conditions, increasing risk of failure. Such conditions include

short to ground, short to battery, and overtemperature. The TPS7B4260-Q1 comes with integrated protection features against each of

these fault conditions, as well as protection against reverse polarity. The device

incorporates a topology containing two back-to-back P-channel metal-oxide

semiconductor field-effect transistors (MOSFETs). This PMOS topology eliminates the

need for an external diode that is otherwise required to prevent the flow of reverse

current. The high 300mA current rating of the device potentially allows a single

tracker to power multiple off-board sensors simultaneously. The device is designed

to handle a 45V (absolute maximum) input voltage and survive the automotive load

dump transient conditions.

The TPS7B4260-Q1 provides a protective buffer for the ADC and MCU against

fault conditions, while securely transferring power to the off-board sensors. A

reference voltage applied at the adjustable input pin (ADJ/EN) is tracked with a

very tight 6mV (max) tolerance at the FB pin. This tolerance holds true for all

variations across the specified line, load, and temperature values. For ratiometric

sensors whose output is sampled by the ADC, this tight tracking tolerance is

particularly benficial. This tolerance makes sure that the error between the ADC

full-scale reference and the sensor power-supply voltage is minimal. The

ratiometricity of the sensor measurement is thereby maintained.

Output voltage becomes equal to the

voltage at the ADJ/EN pin (± the tracking tolerance) by tying the FB pin directly to

the OUT pin. If the ADC full-scale reference voltage equals the sensor supply

voltage, connect the reference voltage directly to the ADJ/EN pin. If the sensor

supply is lower than the reference, use a resistive divider at the ADJ/EN pin. This

divider helps scale down the reference voltage to match the sensor supply voltage.

If the sensor supply is higher than the reference, use a resistive divider between

the FB and OUT pins. This divider helps scale up the ADC full-scale reference

voltage and match the sensor supply voltage.

By setting the ADJ/EN input pin low,

the TPS7B4260-Q1 switches to standby mode. In this

mode, the quiescent current consumption of the LDO reduces to less than 3.8µA.