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how to drive high current 5 volts circuit using 89s52

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abhignans

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hello,
i am using 89s52 micro controller to drive a individual circuit,.i.e i have to power a raspberry pie using 89s52.
the raspberry needs 5 volts,1amp miniimum to power it

i have used a relay to power it but in the cirvuit i have limitation for space
so i have opted for mosfet IRF540 with 4n35 for optical isolation
but when i use this i get only 4.45 volts finally by which the raspberrypie malfunctions

please suggent me a method to give out exactly 5volts 1amp output to be interfaced to the microcontroller

thanks in advance
 

tpetar

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ahmad1954

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that .55 volt drop, is used for biasing. you should use buffer. it cane be done with opamp or prepared Ic.
 

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Use a relay which is controlled by uC. The relay when activated supply 12V power to 7805 1A regulator and the o/p of 7805 is given to rasberrypie. Use PCB mount 12V 300 Ohms Telcom relays from Goodsky.

Google for "GS SH 212T"

See attached .pdf
 

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Tahmid

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hello,
i am using 89s52 micro controller to drive a individual circuit,.i.e i have to power a raspberry pie using 89s52.
the raspberry needs 5 volts,1amp miniimum to power it

i have used a relay to power it but in the cirvuit i have limitation for space
so i have opted for mosfet IRF540 with 4n35 for optical isolation
but when i use this i get only 4.45 volts finally by which the raspberrypie malfunctions

please suggent me a method to give out exactly 5volts 1amp output to be interfaced to the microcontroller

thanks in advance

Can you show the drive circuit employing the 4N35 and IRF540?

The voltage drop you have is quite large. That's because of bad gate drive. Since you're driving with about 4-5V, using a logic level MOSFET (with low Rdson) instead of the Power MOSFET should help.

Hope this helps.
Tahmid.
 

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