Using boost DC-DC converter as switch | 𧨠Engineering Schematic Solutions
Intro
For battery power systems you might want to use simple boost converter to get stable 5V when powered from Li-Ion battery (3.2-4.2V) and going to use EN pin to control it (enable/disable), but here is the caveat in such approach.
π Related
 | π₯ High-side P-Channel Load Switch on discrete components |
 | Powering addressable LED WS2812 5V when system has only 3.3V |
πΊ Issue Description
When EN=0V (pulled to ground) the output voltage in non-zero and close to the input voltage.
β Causing
The inpuΠ΅ voltage is present on the output because of boost converter topology. The current just flow through inductor and diode, so VOUT=VIN-Vdiode
| Async Boost Converter | Sync Boost Converter |
| MT3608 | TPS61088 |
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π§ Issue Fix
But both variants are more expensive. | Add high-side switch for disabling powering likeΒ M9700-N (5V 2A).You can place it at the input or output (iv VOUT<5V). It take more space, but cheaper. |
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β Fixed
After adding switch I have VOUT=0V when EN=0V
Conclusions
| π΄ | Practically most of boost converters doesn't have internal switch, so you need to special boost with output disconnect or buck-boost or add high-side switch |