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From: Tim Wescott on 3 Jun 2010 13:29
Got handed a schematic a couple of days ago with the SN754410, which TI
bills as "an improved version of the L293".

One of the outstanding* features of the L293 is that it is dog slow.
The SN754410, on the other hand, has delay times that indicate that it
could be operated in the tens of kHz, with pulse times down to one or
two microseconds.

Am I reading that data sheet right? Or do I have my head up my
assumptions? This is for a motor control circuit that would work a lot
better if we could PWM it fast enough for the motor to do smoothing, and
that calls for a PWM rate that approaches 100kHz. It's for a really
little motor, so having some super-zoot circuit with gate drivers and a
bunch of discrete transistors would be kinda overkill -- and I'm really
supposed to just be the control guy.

* I didn't say outstandingly good.

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
From: Tim Wescott on 3 Jun 2010 13:40
On 06/03/2010 10:29 AM, Tim Wescott wrote:
> Got handed a schematic a couple of days ago with the SN754410, which TI
> bills as "an improved version of the L293".
>
> One of the outstanding* features of the L293 is that it is dog slow. The
> SN754410, on the other hand, has delay times that indicate that it could
> be operated in the tens of kHz, with pulse times down to one or two
> microseconds.
>
> Am I reading that data sheet right? Or do I have my head up my
> assumptions? This is for a motor control circuit that would work a lot
> better if we could PWM it fast enough for the motor to do smoothing, and
> that calls for a PWM rate that approaches 100kHz. It's for a really
> little motor, so having some super-zoot circuit with gate drivers and a
> bunch of discrete transistors would be kinda overkill -- and I'm really
> supposed to just be the control guy.
>
> * I didn't say outstandingly good.
>
While I'm asking, is there any monolithic H-bridge driver that doesn't
have the gawdawful voltage drop that these things do?

--
Tim Wescott
Control system and signal processing consulting
www.wescottdesign.com
From: langwadt on 3 Jun 2010 13:52
On 3 Jun., 19:40, Tim Wescott <t...(a)seemywebsite.now> wrote:
> On 06/03/2010 10:29 AM, Tim Wescott wrote:
>
> > Got handed a schematic a couple of days ago with the SN754410, which TI
> > bills as "an improved version of the L293".
>
> > One of the outstanding* features of the L293 is that it is dog slow. The
> > SN754410, on the other hand, has delay times that indicate that it could
> > be operated in the tens of kHz, with pulse times down to one or two
> > microseconds.
>
> > Am I reading that data sheet right? Or do I have my head up my
> > assumptions? This is for a motor control circuit that would work a lot
> > better if we could PWM it fast enough for the motor to do smoothing, and
> > that calls for a PWM rate that approaches 100kHz. It's for a really
> > little motor, so having some super-zoot circuit with gate drivers and a
> > bunch of discrete transistors would be kinda overkill -- and I'm really
> > supposed to just be the control guy.
>
> > * I didn't say outstandingly good.
>
> While I'm asking, is there any monolithic H-bridge driver that doesn't
> have the gawdawful voltage drop that these things do?
>

L6201 ?, datasheet says 0.3V at 1A

-Lasse
From: Rich Webb on 3 Jun 2010 14:26
On Thu, 03 Jun 2010 10:29:17 -0700, Tim Wescott <tim(a)seemywebsite.now>
wrote:

>Got handed a schematic a couple of days ago with the SN754410, which TI
>bills as "an improved version of the L293".
>
>One of the outstanding* features of the L293 is that it is dog slow.
>The SN754410, on the other hand, has delay times that indicate that it
>could be operated in the tens of kHz, with pulse times down to one or
>two microseconds.
>
>Am I reading that data sheet right? Or do I have my head up my
>assumptions? This is for a motor control circuit that would work a lot
>better if we could PWM it fast enough for the motor to do smoothing, and
>that calls for a PWM rate that approaches 100kHz. It's for a really
>little motor, so having some super-zoot circuit with gate drivers and a
>bunch of discrete transistors would be kinda overkill -- and I'm really
>supposed to just be the control guy.

For really little, maybe the FAN8200 with 0.4 V at 400 mA (did I mention
it's for really little motors?). Built-in clamp diodes, which is nice,
but the datasheet doesn't mention times or frequency at all.

Hmmm... seems to have fallen off of Fairchild's line card. Ugh. The
Sanyo LB1836M may be a viable replacement.

--
Rich Webb Norfolk, VA
From: Winfield Hill on 3 Jun 2010 21:20
Tim Wescott wrote...
>
> Got handed a schematic a couple of days ago with the SN754410, which TI
> bills as "an improved version of the L293".
>
> One of the outstanding* features of the L293 is that it is dog slow.
> The SN754410, on the other hand, has delay times that indicate that it
> could be operated in the tens of kHz, with pulse times down to one or
> two microseconds.
>
> Am I reading that data sheet right? Or do I have my head up my
> assumptions? This is for a motor control circuit that would work a lot
> better if we could PWM it fast enough for the motor to do smoothing, and
> that calls for a PWM rate that approaches 100kHz. It's for a really
> little motor, so having some super-zoot circuit with gate drivers and a
> bunch of discrete transistors would be kinda overkill -- and I'm really
> supposed to just be the control guy.
>
> * I didn't say outstandingly good.

sn754410, hmm, 9001 in stock at DigiKey, $1.09 qty 1k.
Pretty old, developed circa 1986, but still ticking...


--
Thanks,
- Win
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