The eFuse Alternative

Smart High-Side Switch

The switch communicates with a host controller over an SPI bus, which includes clock, chip-select, data-in, and data-out pins. The device supports simple daisy-chain SPI operation in a primary-secondary configuration, with the controller acting as the primary device that issues commands to, and receives responses from, the TPS2HCS10-Q1, which acts as the secondary device.

The two devices’ SPI communication involves data stored in the TPS2HCS10-Q1’s on-chip memory-mapped registers. The controller can write commands and configuration information to a portion of these registers, and it can read back data from other registers.

For example, one register enables the controller to configure an overcurrent protection function with an adjustable threshold. Another can store a programmable current-time fuse profile, analogous to i2t curves on melting-wire-fuse datasheets.

To enable the controller to read back data, the high-side switch includes a configurable sensing capability coupled with an integrated analog-to-digital converter (ADC). The controller can access ADC output values representing parameters such as load current, output voltage, battery voltage (V_BAT), and FET temperature via TPS2HCS10-Q1 data-feedback registers.

The TPS2HCS10-Q1 can operate in several states, or modes, which the controller can enable by writing commands to state registers. These states include SLEEP state, enabled when a vehicle is parked or in key-off mode. In addition, the device includes a low-power mode (LPM)—a state that supports 800 mA of peak current while consuming about 10 µA of quiescent current.

Then there’s a CONFIG state that allows TPS2HCS10-Q1 registers to be configured over the SPI link, while an ACTIVE state enables normal operation, during which configuration can’t be changed. Finally, a LIMP HOME state places the device in a safe mode in the event of a fault, such as an SPI communication failure.

Evaluating High-Side Switches

To help you evaluate high-side switches like the TPS2HCS10-Q1, TI offers the HSS-HCMOTHERBRDEVM motherboard and a family of daughtercards for its high-side smart-switch portfolio. To get started with the device, order both the motherboard and HSS-2HCS10EVM daughtercard (Fig. 3) and plug the daughtercard into the motherboard to form a complete evaluation module (EVM). Then, connect your computer to the EVM via a USB cable and download the TI Smart Fuse Configurator software.