The Blackbox page as shown in Figure 6-20 implements the Blackbox fault recording feature in TPS25990 eFuse. This feature greatly enhances the system designer's ability to debug power path related issues during design/development and field returns.

After powering up the device, the Blackbox tick timer update rate must be configured in the BB_CONFIG (E5h) register. This is shown in the RED circle in Figure 6-21.

To send the READ_BB_RAM (FDh) block read command for retrieving the contents of seven Blackbox RAM registers, starting from BB_RAM_0 to BB_RAM_6, click on the READ FROM RAM icon as outlined by the RED circle in Figure 6-20. Figure 6-20 shows the retrieved contents in the GREEN rectangular box.

Clicking on the CLEAR FAULTS icon as outlined by a BLUE circle in Figure 6-20 resets the Blackbox RAM registers to zero.

Once the device encounters a global fault or alert event (based on the ALERT_MASK (DBh) register), the Blackbox RAM contents, status registers, peak input voltage, peak input current, peak device temperature, and Blackbox timer values are written to an external EEPROM through the EECLK/EEDATA pins.

The EEPROM interface is a standard I2C controller and operates at 400 kHz clock speed. TI recommends using an I2C EEPROM with minimum 1 kbits of capacity and 16-byte page addressing. Examples of compatible EEPROM devices include 24LC04, 24AA04, etc.

The contents of the Blackbox RAM along with some status registers (STATUS_WORD (79h), STATUS_MFR_SPECIFIC (80h), and STATUS_INPUT (7Ch)) and certain parameters (VIN_PEAK, IIN_PEAK, and TEMPERATURE_PEAK) are stored into Page-0 of an external EEPROM when the following conditions are met. At the same time, Blackbox RAM contents and Blackbox tick timer values are locked.

1. An external EEPROM is successfully connected by setting the EXT_EEPROM bit high in the DEVICE_CONFIG (E4h) register as shown in Figure 6-22. In addition, this is done by configuring two of the four GPIOs as EECLK and EEDATA appropriately in the GPIO_CONFIG_12 (E1h) and GPIO_CONFIG_34 (E2h) registers. This is shown in Figure 6-23. Make sure those two selected GPIO pins are physically connected to the EEPROM clock and data pins respectively on the board.
2. Any one of the three BB EEPROM write trigger bits is set in the BB_CONFIG (E5h) register as outlined by BLUE circle in Figure 6-21.

To access the Blackbox contents from that EEPROM, first click on the FETCH EEPROM icon and then click on the READ EEPROM icon as outlined by the RED and BLACK circles respectively in Figure 6-24. Figure 6-24 shows the retrieved contents in the GREEN GREEN rectangular box.

Clicking on the ERASE BLACKBOX icon while the WRITE PROTECT is unlocked as outlined by the BLUE circles in Figure 6-24 resets the EEPROM Blackbox contents to zero.