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Ch340 Datasheet (I) 1 usb to Serial Port Chip ch340CH340DS1 (1)CH340 Datasheet (I)
3
recommended that no external resistor is in series with UD+ and UD- pins.
4. Pin definitions
SSOP20
Pin No.
SOP16
Pin No.
ESSOP10
Pin No.
SOP8
Pin No.
Pin
Name
Pin
Type
Pin Description (description in bracket is
only applied for CH340R)
19
16
7
5
VCC
POWER
Power supply voltage input, requires an
external 0.1uF decoupling capacitor
8
1
3, 0
3
GND POWER
Ground, connected to ground of USB bus
directly
5
4
10
8
V3
POWER
Connect to VCC when VCC is 3V3, connect
to 0.1uF decoupling capacitor when VCC is
5V
XI
IN
CH340T/R/G: Input of crystal oscillator,
connect to 12MHz crystal and capacitor
NC.
NONE CH340C: No Connection, do not connect
9
7
NONE
NONE
RST#
IN
CH340B: Input of external reset, active low,
integrated pull-up resistor
XO
OUT
CH340T/R/G: Output of crystal oscillator,
connect to 12MHz crystal and capacitor
OUT#
OUT
CH340C: MODEM output IO, software
controlled, active low. Part of batch
number in CH340C switch to 2nd DTR#
optionally
10
8
NONE
NONE
NC.
NONE CH340B: No Connection, do not connect
6
5
1
1
UD+
USB
signal
Connect to USB D+ Signal directly, do not
series resistors
7
6
2
2
UD-
USB
signal
Connect to USB D- Signal directly, do not
series resistors
20
NONE
NONE
NONE NOS#
IN
Forbid USB device suspending, active low,
integrated pull-up resistor
3
2
8
6
TXD
OUT
Transmit asynchronous data output (reverse
output for CH340R)
4
3
9
7
RXD
IN
Receive asynchronous data input, integrated
configurable pull-up and pull-down resistor
11
9
5
NONE
CTS#
IN
MODEM input signal, clear to send, active
low(high)
12
10
NONE
NONE DSR#
IN
MODEM input signal, data set ready, active
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