Original question:
This is a follow up to my previous post. I have made some changes to the schematic, specifically I removed the 68uF and replaced it with 3-22uF 0805's. I have re-done the layout to follow as closely as possible the recommended layout. If you could take a look and let me know if this looks reasonable or if there is anything I might do differently, that would be enormously helpful.
Hi Sean,
In the last post, you mentioned that the input voltage range is 3V~5.2V, and the output voltage is 5V, max output current is 1.2A. Are these still correct for this schematic?
If it is, the schematic and layout is ok.
And more, will the situation that VIN - VOUT > 4.8V not occur in your application? For example, before startup, the output voltage is 0V but the input cap is fully charged already. Or the output voltage is shorted to ground during operation because of something...
If it is possible, a diode between input and output is necessary as Fig.8-13.
Regards,
Nathan
Hi Sean,
It is ok.
By the way, do you have any requirement about the undershoot/overshoot in load transient or line transient?
If that, we recommend to add feedforward cap and resistor (C9 + R10) as shown below, for potential transient performance improvement.
If not, the design now is no problem.
You can leave C9+R10 as placeholder first and mount them when the transient performance needed to be improved.
We recommend R10 is ~50ohm, C9 < 50pF, depended on the test results. Or you could use the calculation tool in the link below to calculate the C9.
Regards,
Nathan
