The Data Sheet of CH340 (the first) 1 USB to serial chip CH340 English Data Sheet Version: 2C The Data Sheet of CH340 (the first) 2 3 Package Package shape Width of plastic Pitch of Pin Instruction of package Ordering type SOP-16 3.9mm 150mil 1.27mm 50mil Small outline package of 16-pin CH340G SOP-16 3.9mm 150mil 1.27mm 50mil Small outline package of 16-pin CH340C SOP-16 3.9mm 150mil 1.27mm 50mil Small outline package of 16-pin CH340B MSOP-10 3.0mm 118mil 0.50mm 19.7mil Shrink small outline package of 10-pin CH340E SSOP-20 5.30mm 209mil 0.65mm 25mil Shrink small outline package of 20-pin CH340T SSOP-20 5.30mm 209mil 0.65mm 25mil Shrink small outline package of 20-pin CH340R Model differences: CH340C, CH340E and CH340B have built-in crystal, no external crystal CH340B also has built-in EEPROM used to configure the serial number,etc.Some functions can be customized. CH340R provides reverse polarity TXD and MODEM signals. (No spot) 4. Pins SSOP20 SOP16 MSOP10 Pin Description (description in bracket is only about Pin Name Pin Type Pin No. Pin No. Pin No. CH340R) Positive power input port, requires an external 0.1uF power 19 16 7 VCC POWER decoupling capacitor 8 1 3 GND POWER Public ground, ground connection for USB Connect to VCC to input external power when 3.3V power 5 4 NONE V3 POWER supply, connect to 0.1uF decoupling capacitor when 5V power supply CH340T/R/G: Input of crystal oscillator, connect to crystal XI IN 9 7 NONE and capacitor NC. NONE CH340C: No Connection, must be suspended RST IN CH340B: Input of external reset, active low, built-in