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I designed a circuit with an FT232RL IC, but Windows doesn't recognize the USB. Please refer to the attached schematic diagram.

schematic diagram

jsotola
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Viraj Parshuram
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    Is it bus powered configuration ?Why have you put an led and resistor in VCC path.. Please refer data sheet FT232 for reference schematics.. – Varun Aug 04 '23 at 08:21
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    You're showing one ground for the USB connector and another for the rest of the circuit. How are they connected together? – Finbarr Aug 04 '23 at 11:09
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    Remove the short circuit selector JP5. – Jens Aug 04 '23 at 15:00

1 Answers1

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The VCC and VCCIO power supply for the FT232R is in series with R31 (1k Ohm) and LED D18. Assuming a 15mA load current through R31, that will lose 1.5V of power supply voltage from USB -- which could be as low as 4.6V per spec, though typical USB host provides 5.1V. Best case that drops FT232R VCC to about 3.5V, which is below the 4.0V minimum operating spec for FT232R in internal oscillator mode. There will also be some non-linear voltage drop across LED D18, probably another 1.0V to 1.5V, assuming it's a red LED. To confirm, try shorting across R31 and D18 (effectively removing them from the VCC path).

FT232R datasheet

FT232R DC Characteristics table

MarkU
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