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I'm trying to switch an array of resistive loads at 12V as fast as possible using least amount of parts due to limited board space. I have tried to find sourcing darlington transistor pairs but they are either not able to provide at least 500mA per channel (simultaneously, so 3.5A sourcing in total) or not fast enough. I need the rise and fall time of the 12V swing to be at most 150 nS each way. The pulse length is around 1.5uS. I've tried looking for sourcing darlington pairs as well as nmos or pmos mosfet arrays that can switch fast enough but all I've found that will be suitable for my needs is individual fets. Does anyone know any alternative methods of switching resistive loads fast in a small smd package?

schematic

simulate this circuit – Schematic created using CircuitLab

Mr_Intro
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  • There are plenty of parts like dual MOSFETs in 2mm x 2mm packages, 4 of those would be pretty small. – Spehro Pefhany Mar 22 '21 at 19:53
  • @SpehroPefhany Diode Inc's [DMHC4035LSDQ](https://www.diodes.com/assets/Datasheets/DMHC4035LSDQ.pdf) is supposed to be a full bridge (2N and 2P) part. But it appears to handle the current and is in one small package. Gate drive current seems reasonable, too, despite the short period. But I've no experience reading the datasheet well enough to work out whether or not these may be fast enough. Are they? – jonk Mar 22 '21 at 20:28
  • @jonk I think MOSFETs are about as fast as you have current to drive the gate charge, in terms of the time scale here (where package parasitics don't come into play). So yes, fast enough but maybe no. – Spehro Pefhany Mar 22 '21 at 20:38
  • Look in the Allegro catalog, they have source driver arrays – Lorenzo Marcantonio Mar 23 '21 at 09:09

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