Need to control the supply to MAX3232 ( RS232_TO_TTL) IC using Arduino. The 3.3V supply is also tapped from the Arduino board. I have to keep the Vcc supply of MAX3232 around 3V. With the present circuit diagram, the voltage drop is around ( hence Vcc indented) is around 2.3V. Should I use a different Rc value or should I use driver level transistor like SL100 and avoid Rc altogether? Thanks.

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    \$\begingroup\$ The MAX3232 is specified to run with a supply of 3V to 5.5V. If it 'heats up immensely' then you're doing something wrong. \$\endgroup\$
    – brhans
    Nov 5, 2020 at 4:05
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    \$\begingroup\$ I wouldn't feed it through a resistor; it will drop voltage depending on the IC's power consumption, and waste energy when the transistor is conducting. Why not use a high-side switch? \$\endgroup\$
    – ocrdu
    Nov 5, 2020 at 4:19
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    \$\begingroup\$ Your circuit makes no sense. What is your goal? Why do you want to switch the power? \$\endgroup\$ Nov 5, 2020 at 4:25
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    \$\begingroup\$ I second what brhans says. Plus, since it's not a good thing to apply a voltage to a chip's inputs when it's unpowered, you should also guarantee that the chip will not get any input from RS-232 when you cut its power. By the way, as others have already stated, the circuit shown in the post is not that efficient. \$\endgroup\$ Nov 5, 2020 at 5:13
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    \$\begingroup\$ The MAX3232 should not heat up so you have some other problem in the circuit. And the power supply switching circuit will cause even more problems, as supply is provided via resistor and turning chip off consumes 15mA via transistor, so it makes no sense. Also @RohatKılıç that is not true, it's a RS232 PHY, it is meant to hanle being connected unpowered to another powered RS232 PHY, or our modems and computers etc would have blown up if they weren't simultaneously turned on. It won't handle the TTL side though so it must have power when MCU outputs logic high. \$\endgroup\$
    – Justme
    Nov 5, 2020 at 5:35


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