If the peaks are very short, I've found the ZTX range of transistors very
good.
I'm most familiar with the ZTX649, 650 & 651 (npn) and ZTX749, 750 & 751
(pnp). Current rating is 2A (only a small E-line package). They switch power
very fast and have low saturation voltages. Very useful for IR transmitters
BTW,
much better than something like a BC337 or BC327 especially for uS pulses

Joe.
>
> Or any alternatives for controlling two 5V devices from digital TTL (or 5V
> and 3.3V later) which take around 500mA (5V), and around 300mA (3V) - but
> with very short 2A peaks (GSM when transmitting).
> Regards
>
> Adrian
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>