The TPS25990 is an eFuse with integrated power switch to manage load voltage and load current. The device is equipped with a PMBus compatible digital interface which allows a host to control, configure, monitor and debug the device. The device starts its operation by monitoring the VDD and IN bus. When V_DD and V_IN exceed the respective Undervoltage Protection (UVP) thresholds, the device waits for the insertion delay timer duration to wait for the supply to stabilize before starting up. Next the device samples the EN/UVLO pin and SWEN pins. A high level on both these pins enables the internal MOSFET to start conducting and allows current to flow from IN to OUT. When either EN/UVLO or SWEN is held low, the internal MOSFET is turned off.

After a successful start-up sequence, the TPS25990 device now actively monitors its load current and input voltage, and controls the internal FET to ensure that the programmed overcurrent threshold is not exceeded and input overvoltage spikes are cut off. This action keeps the system safe from harmful levels of voltage and current. At the same time, a user-programmable overcurrent blanking timer allows the system to pass transient peaks in the load current profile without tripping the eFuse. Similarly, voltage transients on the supply line are intelligently masked to prevent nuisance trips. This feature ensures a robust protection solution against real faults which is also immune to transients, thereby ensuring maximum system uptime.

The TPS25990 allows the host to monitor various system parameters and status over the PMBus interface. It is also possible to change the device configuration over the PMBus interface to control device behavior as per system needs. This includes various warning/fault thresholds, timers and pin functions. The configuration values can also be stored in the internal non-volatile OTP memory or an external EEPROM so that the device can start up with some pre-defined configuration without host intervention at every power-up.

The TPS25990 also provides advanced telemetry features such as high speed ADC sample buffering ("digital oscilloscope") and Blackbox fault recording which simplify system design and debugging and facilitate predictive maintenance.

The device has an integrated high accuracy and high bandwidth analog load current monitor, which allows the system to precisely monitor the load current in steady state as well as during transients. This feature facilitates the implementation of advanced dynamic platform power management techniques such as Intel PSYS to maximize system power usage and throughput without sacrificing safety and reliability.

For systems needing higher load current support, the TPS25990 can be connected in parallel with other high current eFuses like TPS25985x. The TPS25990 acts as a primary controller and enables control, telemetry and configuration of the whole chain over PMBus.

All devices share current during start-up as well as steady-state to avoid over-stressing some of the devices more than others which can result in premature or partial shutdown of the parallel chain. The devices synchronize their operating states to ensure graceful start-up, shutdown and response to faults. This makes the whole chain function as a single very high current eFuse rather than a bunch of independent eFuses operating asynchronously.

The device has integrated protection circuits to ensure device safety and reliability under recommended operating conditions. The internal FET SOA is protected at all times using a thermal shutdown mechanism, which turns off the FET whenever the junction temperature (T_J) becomes too high for the FET to operate safely.