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I'm currently designing the power supply for a device which uses XBee PRO S2C as a medium of communication. We are using a Lipo battery 3.7V 3500 mAh battery and TP4056 based battery charger.

The problem is:

XBee PRO S2C operating voltage is 2.6 to 3.7V. However when the lipo battery is fully charged, its voltage jumps to 4.2V and at this voltage the XBee does not operate and is damaged.

What can be the best option to reduce the Lipo battery supply to feed the XBee power?

I can use a PN diode or Schottky diode, but it works only if the battery voltage level is above 4.0V as it is consuming 0.7V as voltage drop (PN diode) and Schottky depends on current consumption.

The best option I found is using a LDO regulator of operating voltage at 3.0V and low drop out of 0.2V. Will this regulator work for the requirement I'm looking for?

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Yes. Diode's won't be a robust solution, but a small LDO regulator will do exactly what you need it to do. It seems the most current the XBee will use is about 120mA, which is well within a typical LDO regulator's limits.

I am concerned about the battery though. LiPos are large dangerous batteries that are designed for very high currents for short periods. Not a small current for a long period. So, are you designing an IoT type of thing? Or trying to add WiFi to some RC device? In the latter case, awesome!

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  • \$\begingroup\$ yes, we are designing an IOT product for data analytics for monitoring agriculture field, As you said that LiPo is not suitable, for small currents, so what could be the best battery type option that I can provide.Wifi is not using in our project. To avoid the diode can i have a zener based power supply for feeding the xbee which cuts off the voltage greater than what we require. \$\endgroup\$ – Shiv May 31 '18 at 2:53
  • \$\begingroup\$ No, go for the LDO. It essentially has the zener inside and does the rest for you. If you want to design a circuit using a zener you would have to design the power electronics around the zener. And if you knew how to do that we would not be having this conversation. As for the battery, I would go for Li-Ion. A quick google shows what people use here. \$\endgroup\$ – Hein Wessels May 31 '18 at 6:02
  • \$\begingroup\$ Thanks for the suggestion, I finally came to a conclusion to go for an LDO type of Regulator. \$\endgroup\$ – Shiv May 31 '18 at 12:29
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It is 5 volt tolerant because I used an adapter board which I thought must have level shifters and 3.3 volt voltage regulator so I connected 5 volt powered arduino tx directly in xbee rx and it was working perfectly.

later I checked and found that regulator was there but the xbee rx pin was directly connected with arduino tx, I have been doing it for more than 2 years.

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The best option I found is using a LDO regulator of operating voltage at 3.0V and low drop out of 0.2V. Will this regulator work for the requirement I'm looking for?

yes it will

go for an any LDO with a dropout of less than 300mV @ 150mA like MIC5205-3.0BM daatsheet with 3V output.

So that any li-ion battery will make the think work till last 20% of its capacity (appx).

Better design an logic converter between xbee and host, if they are operating at different voltages.

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