how to produce 21 volts from 3.6V

[suncq]

I found the product from the web ,battery powered remotely programmable GSM/GPRS/SMS telemetry unit. It uses 3.6 volts 14.5Ah battery. when for externel sensor, it produce Sensor excitation, 21 volts, at 200mA. Dose anyone know how to do that.
thanks!
suncq@126.com

 

[kender]

Look up inductive step-up converters. They are also called "boost" converters.

Maxim had published a nice app note "An Introduction to Switch-Mode Power Supplies" **broken link removed** . it describes the principles of operation of boost converters (among others).

 

[AVIANO]

One option is discussed by kender, which is a boost converter. Other option is the self oscillator circuit, in which a small transformer (ofcourse ferrite) is self oscillated with one or two windings and produces a square wave stream, which can be rectified and regulated.

 

[TekUT]

Other useful reading about the boost schematic:

https://focus.tij.co.jp/jp/lit/an/slyt279/slyt279.pdf

Bye
Pow

 

[suncq]

thanks all of you. I think TekUT's reply maybe solve my question. I will get a TPS61080 to try.