Hi,
Could you tell me about TPS65185
What is the status of the VNEG、VEE、VPOS、VDDH in VNEG、VEE、VPOS、VDD start up timing?
In this case, these pins Is either of the Hi-Z and Low status?
Best regards,
Yusuke/Japan Disty
Hi Yusuke-san,
From measurements on the EVM, the regulators will go into their active discharge states before being enabled, but the timing did not appear consistent. VNEG and VEE engage their active discharge only when PWRUP is asserted high, whereas VPOS and VDDH engage their active discharge as soon as power is applied.
VPOS and VDDH are high-Z when no power is applied, and when power is applied there is a short window where their outputs are pulled low, followed by the release to their 1kohm discharge resistances. The timing involved does not appear to be consistent however, as each time the regulators would release at different instances, but there was always a window of holding low, followed by a release to the 1kohm impedance to GND as shown in the attached screenshot. These regulators had multimeters on their outputs, configured to measure impedance, causing the pre-bias voltages that you can see are discharged once power is applied to the EVM. VPOS and VDDH behaved the same regardless of the state of the WAKEUP pin.
VNEG and VEE will maintain their ~30kohm impedance until PWRUP is asserted high, after which they will exhibit a very similar short to GND, followed by a release to a lower impedance. But once again, the timing was inconsistent each time the EVM was power-cycled.
