# Maximum current drawn from 3.3 V pin on Spark Core? **URL:** \ **Category:** Hardware\ **Created:** [July 20, 2015, 12:57pm UTC](https://community.particle.io/t/maximum-current-drawn-from-3-3-v-pin-on-spark-core/13511 "2015-07-20T12:57:02Z")\ **Posts on this page:** 4\ **Page:** 1
**Author:** ![matteo\_monti](https://avatars.discourse-cdn.com/v4/letter/m/82dd89/32.png) [@matteo\_monti](https://community.particle.io/u/matteo_monti)\ **Post date:** [July 20, 2015, 12:57pm UTC](https://community.particle.io/t/maximum-current-drawn-from-3-3-v-pin-on-spark-core/13511/1 "2015-07-20T12:57:02Z")
That’s most of it, actually. I am using a Spark Core and I need to power up some leds. I made a PWM driven transistor circuit so that I don’t have to power them up directly with the current drawn from the pins (as far as I understand, they support approx. 40 mA max, so I definitely don’t want to burn them). The energy source for my PWM driven circuit, however, is the 3.3 V pin on the Spark itself, which should be directly connected to the power supply and not go through the most delicate parts of the chip. So: - Am I right about that? Is it safe to use the 3.3 V pin to power up my leds? - What is the maximum current that that pin can provide? Thanks a lot! ---
**Author:** ![Moors7](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/moors7/32/588_2.png) [@Moors7](https://community.particle.io/u/Moors7)\ **Post date:** [July 20, 2015, 1:02pm UTC](https://community.particle.io/t/maximum-current-drawn-from-3-3-v-pin-on-spark-core/13511/3 "2015-07-20T13:02:01Z")
> [@matteo\_monti](#): > > I am using a Spark Core These are probably the ones you're looking for: [http://docs.particle.io/core/hardware/#subsystems-power-regulator](http://docs.particle.io/core/hardware/#subsystems-power-regulator) [http://docs.particle.io/core/hardware/#spark-core-datasheet-electrical-characteristics](http://docs.particle.io/core/hardware/#spark-core-datasheet-electrical-characteristics) ---
**Author:** ![peekay123](https://sea2.discourse-cdn.com/flex026/user_avatar/community.particle.io/peekay123/32/810_2.png) [@peekay123](https://community.particle.io/u/peekay123)\ **Post date:** [July 20, 2015, 1:03pm UTC](https://community.particle.io/t/maximum-current-drawn-from-3-3-v-pin-on-spark-core/13511/4 "2015-07-20T13:03:58Z")
@matteo_monti, the STM32 pins can only sink 20ma and the 3V3 pin can supply a max of 500ma required for both the Core and any user-powered devices. I would not draw more than 150ma from the 3V3 pin. All the info you need is in the Core [documentation](http://docs.particle.io/core/hardware/). ---
**Author:** ![kennethlimcp](https://avatars.discourse-cdn.com/v4/letter/k/c0e974/32.png) [@kennethlimcp](https://community.particle.io/u/kennethlimcp)\ **Post date:** [July 20, 2015, 1:04pm UTC](https://community.particle.io/t/maximum-current-drawn-from-3-3-v-pin-on-spark-core/13511/5 "2015-07-20T13:04:46Z")
@peekay123, same mistake 😛 he needed for Core and we gave Photon 😃