Data Sheet

The DataSheet of CH340 (the first) 2
3. Package
Package shape Width of plastic Pitch of Pin Instruction of package Ordering type
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
4. Pins
Pin No. Pin Name Pin Type
Pin Description(description in bracket is only about
CH340R)
19 VCC POWER
Positive power input port, requires an external 0.1uF
power decoupling capacitance
8 GND POWER Public ground, ground connection for USB
5 V3 POWER
connects of VCC to input outside power while 3.3V,
connects of 0.01uF decoupling capacitance outside
while 5V
9 XI IN
Input of crystal oscillator, attachment of crystal and
crystal oscillator capacitance outside
10 XO OUT
Opposite output of crystal oscillator, attachment of
crystal and crystal oscillator capacitance outside
6 UD+ USB signal
Directly connect to D+ data wire of USB bus, set up
pull-up resistor internal
7 UD- USB signal Directly connect to D- data wire of USB bus
20 NOS# IN
Forbid USB device suspending, active with low, set up
pull-up resistor internal
3 TXD OUT Serial data output(opposite phasic output of CH340R)
4 RXD IN
Serial data input, set up controlled pull-up and
pull-down resistor
11 CTS# IN
MODEM liaison input signal, clear sending, active with
low(high)
12 DSR# IN
MODEM liaison input signal, data equipment is ready,
active with low(high)
13 RI# IN
MODEM liaison input signal, oscillate ring to prompt,
active with low(high)