g******u
发帖数: 3060 | 1 I'm looking for a MOSFET gate driver chip (either half bridge, or individual
driver).
You know that for high side FET driver, nowadays people use the bootstrap
capacitor, when it's dischaged, the FET is turned on. There should be some
chip with on-chip charging circuitry, that keep the capacitor recharged all
the time, thus the MOSFET can be kept always on if needed. This feature is
very important in motor controllers since it delivers more power to the load
when necessary.
I found Linear Tech L | f*****0
发帖数: 489 | 2 I am not sure if I understood your questions, or if you understood them
yourself.
it is next to impossible, if not out right impossible, to find drivers truly
capable of 100% duty cycle, especially on the high-side. it is doable in
theory but I haven't seen it done in practice.
so if you are indeed looking for 100% duty cycle half bridge drivers, well,
you need to change your design.
if you are talking about disable pin, well, just put a mosfet on the ground
pin and depleting that mosfet will tu | g******u
发帖数: 3060 | 3 有是有的，那个linear tech的芯片就号称可以。原文写
In PWM operation an on-chip switching regulator maintains charge in the
bootstrap capacitor even when approaching and operating at 100% duty cycle.
IR的tech note给了个电路，用块555可以实现。基本原理是一个cap放电时负载charge
另外一个cap,然后这两个cap互相对充。 | f*****0
发帖数: 489 | 4 well, then you can do the same with pretty much any half bridge drivers, by
providing a steady power supply to the boost pin. since mosfets don't need
much charge after being fully turned on, all you need is to have a voltage
doublter (one 555 + two caps + two diodes).
I just don't know how it works in reality. | g******u
发帖数: 3060 | 5 you are so right.
that's just exactly what's been told there in IR. |
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