8.1 Overview

The TPS4H000-Q1 device is a smart high-side switch, with internal charge pump and quad-channel integrated NMOS power FETs. Full diagnostics and high-accuracy current-sense features enable intelligent control of the load. The adjustable current-limit function greatly improves the reliability of whole system. The device has two versions with different diagnostic reporting, the open-drain digital output (version A) and the current-sense analog output (version B).

For version A, the device implements the digital fault report with an open-drain structure. When a fault occurs, the device pulls STx down to GND. A 3.3- or 5-V external pullup is required to match the microcontroller supply level. The digital status of each channel can report individually, or globally by connecting the STx pins together.

For version B, high-accuracy current sense makes the diagnostics more accurate without further calibration. One integrated current mirror can source 1 / K_(CS) of the load current. The mirrored current flows into the CS-pin resistor to become a voltage signal. K_(CS) is a constant value across temperature and supply voltage. A wide linear region from 0 V to 4 V allows a better real-time load-current monitoring. The CS pin can also report a fault with pullup voltage of V_CS(H).

The external high-accuracy current limit allows setting the current-limit value by applications. When overcurrent occurs, the device improves system reliability by clamping the inrush current effectively. The device can also save system cost by reducing the size of PCB traces and connectors, and the capacity of the preceding power stage. Besides, the device also implements an internal current limit with a fixed value.

For inductive loads (relays, solenoids, valves), the device implements an active clamp between drain and source to protect itself. During the inductive switching-off cycle, both the energy of the power supply and the load are dissipated on the high-side switch. The device also optimizes the switching-off slew rate when the clamp is active, which helps the system design by keeping the effects of transient power and EMI to a minimum.

The TPS4H000-Q1 device is a smart high-side switch for a wide variety of resistive, inductive, and capacitive loads, including LEDs, relays, and sub-modules.