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Topic: looking for a super source driver chip any ideas? (Read 1 time) previous topic - next topic


Allegro makes the UDN2891A-T that will source 500mA.

.. but you'd better not drive more than one channel at a time, because the saturation voltage drop will enough to probably overheat the package even if you drive just two channels @ 500mA.
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A quick review of the data sheet's first page revealed this...  (I attached the data sheet for the ULN2891)
The suffix 'A' (all devices) indicates an 18-lead plastic dual in-line
package with copper lead frame for optimum power dissipation. Under
normal operating conditions, these devices will sustain 120 mA continuously
for each of the eight outputs at an ambient temperature of +50°C and a supply
of 15 V.

The 500 Ma limit is for one channel driven and is a Max current rating.
@ Crossroads, I stand corrected it was the current limit that I remembered... Not the average current for any one channel.
Unfortunately I didn't read the data sheet before I jumped the gun and posted bad information.
The TPIC6B595 is only good for 150 mA continuous current for all 8 outputs driven at the same time.

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Agree with all comments.
Someone really need to come out with a multi-channel P-channel MOSFET array chip for sourcing current.

The biggest I've seen is 4 channel
and the Rds is awful, 180 ohm.

I think I'd go with discrete p-channel mosfets
this one seems a good compromise of  pretty low Rds, low cost, for a standard part (12V, use an open collector/open drain driver in front of it to turn it on,  or a shift register like TPIC6x595 (6A, 6B, 6C, 6D from avnet.com, compare prices))

Or this one
if you're sourcing current from 5V and and control it directly from ATmega outputs, of shift register like 74HC595.
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im looking for a source driver than drive 500mA per output channel.

You may want to look into dc/dc converters: they can be easily configured to produce your desired current levels and they are much more efficient than linear solutions, especially at that kind of current levels.

All you do is to use a resistor to program the desired current levels.


If you don't mind smd devices, using individual mosfets would probably work well
Jw, what's the application? If its fast switching there may be other considerations

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