Background:
As a hobbyist, every circuit I have designed was either powered by a 5V source, e.g., a USB jack, or by a battery. For battery power, I use a switching jack to isolate the battery during charging, which is a common practice the the RC equipment with which I am familiar. With my present project, I am considering allowing USB charging without use of an switching jack. There are two possibilities I have considered: 1) Use a mosfet switch to isolate the device while under charge; or 2) Simply put the system voltage regulator in series and allow charging and operation during charging. EDIT: The P-mosfet and direct connection to V-USB would be deleted from the circuit without isolation.
Details:
The system will be powered by a single lipo battery and operating voltage will be 3.3V. The battery charger will be a Microchip MCP73831/2. The system regulator (VR) will be an LDO MIC5319 or similar with an enable function. On/Off will be a single push button switch with "soft power." That is, first push is on, and second push is off, which will be done by controlling the enable function of the VR. I haven't decided whether to make the soft-power using discrete components (e.g., a pair of NAND gates) or a single chip (e.g.,MAX16054) that also provides debouncing of the on/off switch push button.
Questions:
1) Any opinions on not isolating the battery during charging?
2) Opinions on the following circuit outlined with dashes to provide isolation?
NB: That is just a random P-MOSFET form Eagle's library and is not the one that will be used.
As a hobbyist, every circuit I have designed was either powered by a 5V source, e.g., a USB jack, or by a battery. For battery power, I use a switching jack to isolate the battery during charging, which is a common practice the the RC equipment with which I am familiar. With my present project, I am considering allowing USB charging without use of an switching jack. There are two possibilities I have considered: 1) Use a mosfet switch to isolate the device while under charge; or 2) Simply put the system voltage regulator in series and allow charging and operation during charging. EDIT: The P-mosfet and direct connection to V-USB would be deleted from the circuit without isolation.
Details:
The system will be powered by a single lipo battery and operating voltage will be 3.3V. The battery charger will be a Microchip MCP73831/2. The system regulator (VR) will be an LDO MIC5319 or similar with an enable function. On/Off will be a single push button switch with "soft power." That is, first push is on, and second push is off, which will be done by controlling the enable function of the VR. I haven't decided whether to make the soft-power using discrete components (e.g., a pair of NAND gates) or a single chip (e.g.,MAX16054) that also provides debouncing of the on/off switch push button.
Questions:
1) Any opinions on not isolating the battery during charging?
2) Opinions on the following circuit outlined with dashes to provide isolation?
NB: That is just a random P-MOSFET form Eagle's library and is not the one that will be used.
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