TPS7B4259-Q1

The TPS7B4259-Q1 is a monolithic, integrated low-dropout voltage tracker. The device is available in an 8-pin HSOIC package. The TPS7B4259-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 the risk of failure. Such conditions include short to ground, short to battery, and overtemperature. The TPS7B4259-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 150mA 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 TPS7B4259-Q1 features an independent enable pin (EN) and power-good functionality that detects both under- and overvoltage fault conditions. By setting the EN input pin low, the TPS7B4259-Q1 switches to standby mode. In this mode the quiescent current consumption of the LDO is less than 3.8µA (max).

The TPS7B4259-Q1 provides a protective buffer to the ADC and microcontroller (MCU) against fault conditions, while securely transferring power to the off-board sensors. A reference voltage applied at the adjustable input pin (ADJ) is tracked with a very tight 6mV (max) tolerance at the OUT 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 beneficial. This tolerance verifies 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.

If the ADC full-scale reference voltage equals the sensor supply voltage, connect the reference voltage directly to the ADJ pin. If the sensor supply is lower than the reference, use a resistive divider at the ADJ pin. This divider helps scale down the reference voltage (to a minimum of 2V) to match the sensor supply voltage.