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LTC7001 PWM High-Side Motor Driver

Hi,

we run into Problems when using the LTC7001 for a Brushed Motor Control. We want control the Input Pin with a 20kHz PWM Signal. We have this Circuit:

I already added the TVS Diode from GND to Ts Pin.

The Problem:

The FET has a Qg from 75nC so for PWM i decided to use 100nF Boost Capacitor. But The Gate Voltage will only go up to Ts + 5V.

Then i changed the Boost Capacitor to 1uF now i will have a Gate Voltage of Ts + 12V but with 80% PWM the Driver Stops after some seconds working, will pause a second and remain working. I can't figure out why the driver is stopping.

Can somebody explain this? OV and UV are at Max and Min values. I don't see any Voltage drop on VCC.

Thank you,

Florian

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  • Ok, i figured out, that with +5V VCC Supply the Charge Pump can not supply enough current in PWM mode. I changed the VCC Supply to the +12V from the Main Supply. But with the Voltage drop from starting the motor spinning, the LTC7001 don't survived. I then added an SEPIC Converter to supply the LTC7001 with +12V. This was the solution for the problem. I can now drive the Motor with an 20kHz PWM Signal.

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  • Ok, i figured out, that with +5V VCC Supply the Charge Pump can not supply enough current in PWM mode. I changed the VCC Supply to the +12V from the Main Supply. But with the Voltage drop from starting the motor spinning, the LTC7001 don't survived. I then added an SEPIC Converter to supply the LTC7001 with +12V. This was the solution for the problem. I can now drive the Motor with an 20kHz PWM Signal.

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