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Question about gate drivers and bootstrapping
Hello everyone
I want to design an h-bridge DC motor driver IC using discrete MOSFETs and a gate driver.
Now, most motor drivers I have seen use a half-bridge gate driver like the IR2184, which utilizes a bootstrap circuit to use the NMOS as a high-side switch.
As far as I understand, bootstrap operation requires you to continuously alternate between the 2 MOSFETs in order for the bootstrap capacitor to have time to charge.
This is all good if, for example, I feed a 50% duty cycle PWM signal to the driver, in that case, the motors will keep running at 50% speed just fine. Now what if I run them at 100% (i.e. feed a fixed input voltage) for a long time? will the driver work for a little bit then the bootstrap capacitor gets discharged and the driver stops? and how can this be handled without limiting the duty cycle to, for example, a maximum of 90%?
thank you
I want to design an h-bridge DC motor driver IC using discrete MOSFETs and a gate driver.
Now, most motor drivers I have seen use a half-bridge gate driver like the IR2184, which utilizes a bootstrap circuit to use the NMOS as a high-side switch.
As far as I understand, bootstrap operation requires you to continuously alternate between the 2 MOSFETs in order for the bootstrap capacitor to have time to charge.
This is all good if, for example, I feed a 50% duty cycle PWM signal to the driver, in that case, the motors will keep running at 50% speed just fine. Now what if I run them at 100% (i.e. feed a fixed input voltage) for a long time? will the driver work for a little bit then the bootstrap capacitor gets discharged and the driver stops? and how can this be handled without limiting the duty cycle to, for example, a maximum of 90%?
thank you
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