- Sat Feb 06, 2016 2:16 pm
#40579
TL;DR: https://github.com/Adam5Wu/Micro-power- ... ent-design
I have been searching for efficient power solution for battery operations.
I was aware of linear regulators, but converting excessive voltage as heat doesn't seems to efficient enough;
Then, I found TPS63025x, which seems to be the best switching mode micro-power supply when it comes to <1mA current draw. But still, the 35uA Iq (realistically, about 45uA with everything assembled) seems a bit too high, compared to 2uA Iq of MCP1700.
While at working current draw SMPS is far more efficient than linear regulators, because we must keep the chip sleeping most of the time, so quiescent current is still a very important factor.
Recently I came across MC33464, a power supervisory chip, which seems to be the missing piece for creating the super high efficiency micro-power SMPS!
Basically, it is an under-voltage detector, like an automated switch, when voltage goes above or below threshold, it flips states. What is good about this chip, is the current draw is super low -- ~1uA.
My idea is to make this chip control the SMPS states to significantly reduce the quiescent current. Just like the thermostat for AC system, which regulates the room temperature while saves power by keeping the AC off most of the time, if the room has enough insulation; I could use this chip to regulate the voltage and keeping the SMPS off most of the time, while the esp power draw is very low.
TPS63025x does have a shutdown mode, during which the Iq reduces to 0.1uA. So with MC33464, the Iq of both chips would be around 1.1uA (*) -- as long as the Vout is about threshold; when Vout drops below threshold, MC33464 turns on TPS63025x, which quickly pumps the Vout up; then MC33464 detects the Vout is above threshold, the turn off TPS63025x, the cycle repeats.
(* the system Iq would be higher, due to the need of pull-up/drain)
With this design, it is possible that this SMPS could have comparable Iq with MCP1700, while have 95% efficiency during load, making it a much superior battery power supply!
I have been searching for efficient power solution for battery operations.
I was aware of linear regulators, but converting excessive voltage as heat doesn't seems to efficient enough;
Then, I found TPS63025x, which seems to be the best switching mode micro-power supply when it comes to <1mA current draw. But still, the 35uA Iq (realistically, about 45uA with everything assembled) seems a bit too high, compared to 2uA Iq of MCP1700.
While at working current draw SMPS is far more efficient than linear regulators, because we must keep the chip sleeping most of the time, so quiescent current is still a very important factor.
Recently I came across MC33464, a power supervisory chip, which seems to be the missing piece for creating the super high efficiency micro-power SMPS!
Basically, it is an under-voltage detector, like an automated switch, when voltage goes above or below threshold, it flips states. What is good about this chip, is the current draw is super low -- ~1uA.
My idea is to make this chip control the SMPS states to significantly reduce the quiescent current. Just like the thermostat for AC system, which regulates the room temperature while saves power by keeping the AC off most of the time, if the room has enough insulation; I could use this chip to regulate the voltage and keeping the SMPS off most of the time, while the esp power draw is very low.
TPS63025x does have a shutdown mode, during which the Iq reduces to 0.1uA. So with MC33464, the Iq of both chips would be around 1.1uA (*) -- as long as the Vout is about threshold; when Vout drops below threshold, MC33464 turns on TPS63025x, which quickly pumps the Vout up; then MC33464 detects the Vout is above threshold, the turn off TPS63025x, the cycle repeats.
(* the system Iq would be higher, due to the need of pull-up/drain)
With this design, it is possible that this SMPS could have comparable Iq with MCP1700, while have 95% efficiency during load, making it a much superior battery power supply!
Last edited by AdamWu on Mon Apr 18, 2016 12:36 am, edited 2 times in total.
