The power bank USB chargers contain a Iithium ion battery and two electronic circuits:Does anyone know whether or not these external lithium battery banks people use for charging their phone or as a battery back-up, have a regulated output. I'd like to use one as a power source for a device I'm making.
Servos draw a lot of current for a short time when they are activated, often more than one amp. This can cause drop-outs in the 3.3 Volt supply which will seriously interfere with the operation of the microprocessor.Thanks dendad, that was something I was unaware of. My micro is super low current and the quiescent current for the sound module is quite low. Not sure what the quiescent is on the servo but since I don't know the cut-off threshold, I'd be guessing anyway.
The instantaneous current drawn by the servo could cause the 5 Volt supply to momentarily drop below the input threshold voltage of the 3.3 Volt regulator.The diode will block this and the capacitor will maintain the input voltage until the supply recovers.Thanks Keith. I have included a 10uF cap across the 5 volt input using regular batteries as a power source and successfully controlled the servo albeit without much of a load on the servo which I know will make a difference although the load ultimately will not be extremely demanding. Also have a very low noise, LDO regulator for the 3.3V's with in and out caps and a pin that increases noise reduction with another smallish cap.
You include the diode because you think the servo might get 'spike-y'?
If you are going to use that battery bank you have several choices:So I hooked up a battery bank I had and got a solid 3.3V out of the regulator and ran the servo without it glitching anything however, this time out between the circuit in action (servo moving) where there is a auto-shutdown in the battery bank looks like a real problem. When there is no servo activity for a minute or so, battery output is lost. Quiescently the circuit draws 33ma and I guess that's not enough for the battery pack to remain engaged.
|Thread starter||Similar threads||Forum||Replies||Date|
|F||USB and External Power Conflict ?||Analog & Mixed-Signal Design||2|
|G||Confirmation of connections of PIC18F87J50 and external memory||Microcontrollers||0|
|work done by an external force in moving a charge Q in an electric field||Homework Help||3|
|M||Why do we need external crystal oscillator if already having internal RC oscillator ?||Microcontrollers||19|
|R||can someone help me to understand how should i attach an external antenna , to this circuit and to disable the internal antennae ?||Wireless & RF Design||7|
|USB and External Power Conflict ?|
|Confirmation of connections of PIC18F87J50 and external memory|
|work done by an external force in moving a charge Q in an electric field|
|Why do we need external crystal oscillator if already having internal RC oscillator ?|
|can someone help me to understand how should i attach an external antenna , to this circuit and to disable the internal antennae ?|
by Luke James