This is the first time I'm playing with motor control... using a=20
TLE5205-2 motor controller/driver chip to run a large throttle body, and=20
it's getting very hot.  I'm figuring there are a few reasons for this...

(1) The throttle body is large -- drawing up to 4-5A continuous.

(2) The PWM frequency is high (~4Khz currently, but that's lowest it=20
seems I can get right now w/o lowering the osc frequency).  The=20
datasheet doesn't specify the max PWM frequency, but I came across an=20
app note (more of a sales sheet) that talks about the merits of their=20
different motor control devices, and there it says that these devices=20
can be controlled by PWM up to 2Khz.  The datasheet specifies switching=20
times of up to 30us, but that's for resistive loads, and I'm driving a=20
large inductive load.

(3) The "Low Rds on, typ 200mohm per switch" is actually quite high I=20
think.  That quote is on the first page "Features" section, but the=20
electrical characteristics show that typical is 220 & 230 mohms per=20
switch, and max is 350 mohms each switch at 25 deg-C. Those only get=20
higher as temp rises.  Ballpark bestcase math here =3D 5A x (220+230) =3D=20
2.25W.  FWIW. max power =3D 3.5W.  That's significant for an SMD part.

Is this correct?  Or am I doing something wrong here.  The only thing I=20
can really control at this point is the PWM frequency, but not sure if=20
that will bring it to "normal" operating temps, due to the power calcs. =20
Somehow though, they specify that this chip can do 5A continuous, so=20
what might I be missing here?

Cheers,
-Neil.

--=20
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