Other Parts Discussed in Thread: TINA-TI
Tool/software:
Hi,
I am planning on using the TPS7H4010 in the inverting buck-boost configuration to supply -6V from +5V. I have downloaded the TINA-TI transient simulation and have had good luck simulating this regulator for both positive and negative supply configurations.
When drawing the schematic for my application I realized that the PGOOD pin (among other pins) needs to be level shifted to 0-3.3V for my MCU. I found app note snva856b.pdf helpful for this.
When I probed the PGOOD pin in the simulation (with no level shifting, only pulled up to GND through a 100K resistor), it always stays asserted at -6V. I ran the simulation for 10ms, but it stayed at -6V. To confirm it works correctly I probed PGOOD on my +6V simulation and it works correctly.
I found this thread helpful, and according to this PGOOD should work as I expect. It will be -6V until the power is good, then it will be pulled up to GND by the resistor in the case of the TINA-TI simulation.
Is this simply an issue with the SPICE model? Can I safely assume that PGOOD works correctly even when the TPS7H4010 is used in an IBB configuration?
I've attached my TINA-TI schematic and output waveforms for your reference. Vpg is the PGOOD signal. You can see that Vout ramps down to -6V, and Vpg with it. But Vpg stays at -6V and is never de-asserted.
Thank you,
Chad
