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step-up or boost with MC34063
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gbg:
How use MC34063 to boost a 3.7v/2200mAh battery to 12v or 9v and 700mA?
Thanks
Ian.M:
Don't!  Choose a different IC, designed specifically to boost from a single cell LiPO.

700mA @ 12V is 8.4W, which will require more than 2.8A input current at the battery's end of discharge voltage, far more than a MC34063 can handle without an external switching transistor.  Although the MC34063A can theoretically work down to 3V, its horribly inefficient at low voltages and wont provide enough gate drive to switch an external MOSFET effectively with under 4V supply.  It also doesn't have any protection against over-discharging your battery.
ogden:

--- Quote from: gbg on February 23, 2019, 08:26:25 pm ---How use MC34063 to boost a 3.7v/2200mAh battery to 12v or 9v and 700mA?
Thanks

--- End quote ---

By reading datasheet. First you have to understand how low power 200mA booster works, what defines it's output voltage (hint: Figure 9. Step−Up Converter). After you are familiar with IC, you may improve it with external switch (hint: Figure 10. External Current Boost Connections for IC Peak Greater than 1.5 A).
gbg:

--- Quote from: Ian.M on February 23, 2019, 08:52:11 pm ---Don't!  Choose a different IC, designed specifically to boost from a single cell LiPO.

700mA @ 12V is 8.4W, which will require more than 2.8A input current at the battery's end of discharge voltage, far more than a MC34063 can handle without an external switching transistor.  Although the MC34063A can theoretically work down to 3V, its horribly inefficient at low voltages and wont provide enough gate drive to switch an external MOSFET effectively with under 4V supply.  It also doesn't have any protection against over-discharging your battery.

--- End quote ---
is LM2577 good for me?
gbg:

--- Quote from: ogden on February 23, 2019, 08:56:40 pm ---
--- Quote from: gbg on February 23, 2019, 08:26:25 pm ---How use MC34063 to boost a 3.7v/2200mAh battery to 12v or 9v and 700mA?
Thanks

--- End quote ---

By reading datasheet. First you have to understand how low power 200mA booster works, what defines it's output voltage (hint: Figure 9. Step−Up Converter). After you are familiar with IC, you may improve it with external switch (hint: Figure 10. External Current Boost Connections for IC Peak Greater than 1.5 A).

--- End quote ---
is this work?
https://cdn.instructables.com/FPM/CQPR/HV0KZ00Z/FPMCQPRHV0KZ00Z.LARGE.jpg
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