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I am looking for a darlington array IC like the ULN2803a that can sink up to 1.5A. It needs to be in a DIP. Any recommendations? Its needed because i am driving a stepper motor and requires 1.2A per coil. I am controlling the stepper motor from a PIC. So if you have another solution let me know.

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I don't think you will find a Darlington array in DIL that will handle 1.5A per output. The package can't dissipate enough power. You will probably have to use use discrete devices.

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  • \$\begingroup\$ If there's only a 0.2V drop, then that's ~300mW per output -- still too much for DIL? \$\endgroup\$ – tyblu Feb 12 '11 at 18:46
  • \$\begingroup\$ That means very low saturation voltage devices, I don't think that they are available in DIL packages. \$\endgroup\$ – Leon Heller Feb 12 '11 at 18:52
  • \$\begingroup\$ Ok have you got any ideas then? \$\endgroup\$ – Dean Feb 12 '11 at 18:59
  • \$\begingroup\$ If you need a through hole package but not necessarily DIP, there are some higher power packages and hybrid chips. Don't know Darlington arrays off the top of my head, though. \$\endgroup\$ – XTL Feb 12 '11 at 19:26
  • \$\begingroup\$ Any thing that could do the job doesn't need to be a DIP. If you know of transistors that could do the job then I would use those. \$\endgroup\$ – Dean Feb 12 '11 at 19:44
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At 1.5A you want to be using MOSFETS,not darlingtons. Unfortunately the best MOSFETS come in SMD packages, but you'll find through-hole parts that will dissipate almost nothing at 1.5A

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  • \$\begingroup\$ I'd already thought of these as an alternative. \$\endgroup\$ – Dean Feb 14 '11 at 17:12
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If you're dead-set on DIPs, N/P-channel MOSFET arrays are fairly common, and they still put some of them into 8-DIP packages, e.g. the Alpha & Omega Semi AOP609 (or 605, 607, 610).

Dropping the thru-hole requirement, it might be cheapest for a low-volume application to just use 4 discrete transistors, plus you have (for better or worse) full control over the specs (aka, you get to figure out which of the millions of MOSFETs to use).

MOSFETs are superior to BJTs in switching applications, as they have no fixed voltage drop (Vce(sat)), just a relatively small Rds(on), which in low-voltage circuits, will provide much lower losses.

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