Hi,
I use a TPS65070 to power my L138 board. A short while ago I mistakenly connected the battery in the opposite direction: battery high to board GND, battery low to TPS65070 battery input (pin 5 & 6, see SLVS950C). The time for this wrong connection lasted for less than 30 seconds but the battery still went hot, and the L138 chip also has some appreciable temperature rise from room temperature.
After reconnect the battery in the correct direction I found the chip no longer work.
- The device can be boot from SPI flash and there is bootable code written into the flash, but booting failed.
- When using SpectrumDigital XDS560V2 to connect to the chip it gives the following error message:
This made me think that the chip might have been damaged due to the reverse voltage/current and the effect of the raised temperature. But quite surprisingly, the chip’s oscillator could still work. I have a 24 MHz crystal connected to the chip per “Figure 5-6. On-Chip Oscillator” of L138 datasheet SPRS586C and could still observe 24 MHz oscillation. Of course the crystal cannot oscillate itself without the effect of the oscillator inside the chip, so does this mean that at least the crystal oscillator part of the chip still works? Or actually the full chip is still fine?
The power supply module, although being like the “first line of defense” to the reverse voltage hence also the “first victim” , still gives correct voltage output from for DCDC1, DCDC2 and DCDC3, LDO1, LDO2 pins. If no other problems happened, these voltages should power the L138 chip well.
From the facts list above (boot failed + emulation failed + oscillator worked + power good), what conclusion can we draw regarding the chip status? Is it possible to have been already damaged?
Paul
