Hi,
Please may I ask some questions on the TPSM5D1806?
Setting the output with more a more accurate feedback resistor ratio
I notice that the TPSM5D1806 recommends setting a lower feedback resistor of 10 kΩ, and calculating an appropriate feedback resistor based on that.
For a 1.8 Volt output, this would give a 26.1k top resistor and 10k bottom resistor (as configured in WEBENCH). Calculating this backwards from a 0.5 Volt reference gives 1.805 Volts output.
If the top/bottom resistors are changed to 390k/150k, this gives exactly 1.8 Volts, removing a source of error on the DC setpoint. Is there any reason why the bottom resistor is set to 10k, other than simplifying the calculation of the output voltage? If different values of lower feedback resistor are possible, what are the constraints on this range? I can't see any feedback pin leakage current specified in the datasheet, but would probably set a value below 10k to minimise this.
Dual-output rail design pulled from WEBENCH?
Also, I did a WEBENCH design for a dual-output TPSM5D1806 back in December. I've tried to create a new WEBENCH design based on this part, but it's only available in dual-phase (12 Amp) output mode. The tool says that this is not supported in dual-channel output, and I can't simulate it in PSpice for TI, either. Fortunately, I can still open up the December project, which I emailed myself the link to. Do you have any idea why it's no longer available in WEBENCH?
Part availability
Finally, I have some concerns about the availability of this part. It is currently out of stock, and Mouser expects stock in Summer 2023, which is over 1 year away. We've ordered some stock in advance of a limited production run, but I'm concerned about embarking on any new design work with this part if we cannot buy stock. Any help or advice with availability would be appreciated.
Many thanks indeed in advance for your help with these questions!
xueliang
best wishes!
