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SMD alternative to TIP31 and TIP32
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Yansi:
Beware of the maximum combined current with these arrays.  Loading all 7 ( 8 ) channels fully at once is not permissible.

But there are other types of arrays, even protected ones (both OCP and OTP), that would be way more suitable for any interfacing cards. Downside of these is usually quite higher price, but they are VERY robust. (typical quad and octal switches for PLC application).

I think a very interesting one for the OP might be for example Rohm BD8LB600FS, octal protected low side switch.  (or any variation on this chip, I think I have seen one even cheaper, about $2 in small quantities - which is a very good price, considering this is a rugged switch, not just a bunch of unprotected transistors)
rsjsouza:
I am not sure if I am missing something, but a cursory glance at a SOT23 device (Onsemi FSB560A) shows 2A of maximum IC and 300mV of VceSat - however, only rated at 500mW of maximum Pd. The ancient TIP31 respectively handles 3A, 1.2V and hefty 40W on its beefy TO220 package. I can't help but wonder that the old device would be much more reliable than a puny modern one.
T3sl4co1l:
SOT89s go up to 5A and more (and a watt or two).  Perfectly reliable if you're not a dick to them. ;D

Tim
floobydust:
Big ugly through-hole is tough. TIP-31 datasheet is 2W no extra heatsink and 40W on a heatsink. If the servo motor can jam or get overloaded, a SOT-23 BJT would exit in a puff of smoke. MOSFET's look much stronger, or Zetex BJT's which are great for low VCE(sat).

I wonder what OP is using for overcurrent protection, aside from the TIP-31 heating up.
v8dave:
Sorry, all. I got the current wrong. It is 40mA max as the coils are 250 ohm and 2 of them wired in parallel. I was thinking of the solenoid valves which are 500mA. I should have looked at my circuit before I posted.

The circuit is shown here. The drive to the servos is +-5V with 0V obviously being off and +-5V fully on for each respective direction.

Input T4 is 0 to 10V analog with 5V being the midpoint from a micro controlled DAC.

T4A and T4B are the connections to the servo. As said, this has 2 coils, each of which is 250 ohms and they are wired in parallel. The feedback is used to give an indication on the control panel and if the servo is faulty, there is no feedback.

The design from the DAC side cannot be changed as the input from the micro already exists.
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