Re: N channel Mosfet H bridge drive

From: Winfield Hill (Winfield_member_at_newsguy.com)
Date: 03/11/04 

Date: 10 Mar 2004 15:43:10 -0800

Rob Turk wrote...
>
> Richard wrote ...
>>
>> I am building 2 H bridges to drive a bipolar stepper motor controlled by
>> a PIC. I would like to apply 50 to 80 volts. I understand that there are
>> H bridge drivers for the mosfets like HIP4081A. But find them a bit
>> costly almost $10USD a piece and I need 2 pieces. Is there an alternative
>> to make a charge pump circuit to solve the problem of switching on the
>> upper channel FETs?

 Intersil's HIP4081A is one of my favorite parts, but it's intended to
 drive four external power MOSFETs at frequencies up to 2MHz, or large
 very high current FETs at lower frequencies if you need. So it's not
 likely to be a very good choice for motor driving. In that family,
 the HIP4082 makes more sense. Newark has the soic package for $3.30

> LMD18245, 55V@3A (6A peak). If you ask nicely, National may send you
> two samples.

 A nice result, if it happens. They're $13 each and neither Newark nor
 DigiKey (who both carry the chip) has any in stock (Newark says 38-day
 lead time, and DigiKey is fresh out).

 Unlike the HIP4081A, the LMD18245 includes the H-bridge FETs (but for
 use up to 3A only). Allegro have the 3948, 3952 and 3958 full-bridge
 (including MOSFETs) PWM drivers, but I couldn't quickly find any stock.

 Thanks,
    - Win

 whill_at_picovolt-dot-com

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