The data sheet doesn’t show resistors in the bootstrap circuits in Figure 1, but do show them in the typical application drawing, Figure 6. However no information is given on the values of either the resistor or the capacitor or how they should be calculated. The eval board schematic shows values of 100 nF and 10 ohms. Should they be taken as suitable for all designs?
I am using this device to drive a 50 ohm impedance speaker that I do not have electrical details on. How can I design the compensation network to work with a range of loads?
Several places in the data sheet it talks about protection circuits “latching off” the device. They don’t make it clear if in every circumstance the FT- flag is pulled low, such as with the OVP.
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Hi,
Your assumption about the 100nF and 10 Ohm values being suitable for all designs is correct, these are generic values that can be tweaked. They are a great place to start and you may find that you don’t even them. I would in the very least include them in your schematic and layout, and if you decide not to use them later you can DNP.
You can follow the compensation network section of the datasheet to design for specific loads, if you want something with variability you could try using a potentiometer instead, but this could cause stability issues. I would start with testing the evaluation board of the device with its comp values to see how it fares with your speaker and load and go from there.
The FT pin will be pulled low if the device is currently in a fault condition. If it is not pulled low, the device should be performing normally.
Thanks,
Brendan Schoemehl
Field Applications Engineer
Monolithic Power Systems | MPS Now