# MP6540HA current-sense frequency response

Greetings,

I have a question regarding the MP6540HGU-A motor driver.

It was stated on another topic that the maximum response frequency of its built-in current-sense circuitry is 100 kHz.
Can you state which criterion for the signal amplitude/distortion was used to determine that as a cutoff frequency? All I can gather from that topic is that in that case the IC stops working since it enters the OTP condition.
So in reality, the usable bandwidth is less than 100 kHz?
Is the 100-kHz frequency the -3dB point, i.e. what is the current-sense ratio at that frequency?
Is it possible that we get the full amplitude-frequency characteristic (variation of the current-sense ratio as a function of frequency)?

I hope you can help me with this inquiry.

Best regards,
Domagoj TomiÄ‡

Hi Domagoj,

Iâ€™ll follow up with our AE that helped answer the last forum topic and post their feedback here.

After discussing with our AE team, here is the information we can provide at this time:

The true bandwidth of the amplifier is >1Mhz. The driver cannot switch faster than 100khz so the signal bandwidth is bounded to 100khz. Thatâ€™s where the â€śbandwidth limitationâ€ť came from.

For further testing, Iâ€™d recommend using our evaluation board for this IC:
EV6540HA-U-00A

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The true bandwidth of the amplifier is >1Mhz.

So I assume that means that the sense amplifier will have a fairly flat frequency response (less then Â±0.2 dB variation) up to 100 kHz.

The driver cannot switch faster than 100khz

This means that the PWM frequency should not exceed 100 kHz?
Because, in the â€śElectrical Characteristicsâ€ť table in your datasheet, the â€śOperation currentâ€ť for PWMx = 200kHz is given, and also shown on the â€śOperation Current vs. PWM
Frequencyâ€ť graph.

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