Data Sheet

The Data Sheet of CH340 (the first) 5
Dat
a transfer pins contain: TXD and RXD pin. RXD keeps high when UART reception is idle.
For CH340G/C/T/R chip, If R232 pin is driven high, assistant RS232 function will be enabled, an
internal inverter will automatically insert to the RXD pin , and the pin becomes low by default. When
UART transmission is idle, the TXD pin of CH340G/C/B/T keeps high, while CH340R keeps low.
MODEM liaiso
n
signal pins contain: CTS#, DSR#, RI#, DCD# and RTS#. All these MODEM liaison
signal are controlled and function defined by computer applications.
Assistant pins contain: IR#, R232, CK0, ACT# and TNOW. When IR# is low-level, infrared serial
interface mode is enabled. R232 pin is used to control assistant RS232 function. If R232 pin is driven
high, the RXD pin input will be reversed automatically. ACT# pin is USB device configuration
complete status output (such as USB infrared adapter ready). TNOW pin indicates CH340 is
transmitting data from UART when it is high-level and becomes low when transmit over. In RS485
and other half-duplex mode, TNOW could be used to indicate UART transmit-receive status. IR# and
R232 are detected only once when chip powered on and reset.
CH340 has built-in separate transmit-receive buffer and support
s simplex, half-duplex and full
duplex UART communication. Serial data contains one low-level start bit , 5, 6, 7 or 8 data bits and 1
or 2 high-level stop bits, supports odd/even/mark/space check. CH340 supports common baud rate:
50, 75, 100, 110, 134.5, 150, 300, 600, 900, 1200, 1800, 2400, 3600, 4800, 9600, 14400, 19200,
33600, 38400, 56000, 57600, 76800, 115200, 128000, 153600, 230400, 460800, 921600,
1500000, 2000000 etc.
Th
e b
aud r
ate error of CH340 UART reception allows not less than 2%, the baud rate error of
CH340G/CH340T/CH340R UART transmission is less than 0.3%, less than 1% for CH340C/CH340E/
CH340B.
In the Windo
ws operation system, CH340 driver can emulate standard serial port. So the mostly
original serial applications are totally compatible, without any modification.
C
H340 can
b
e used to upgrade the serial interface peripherals, or expand extra serial port for computers via
USB bus, through external level conversion chip provide further RS232, RS485, RS422 interface, etc.
Only need to add infrared transceiver, CH340R can expand SIR infrared adapter for computer via USB bus,
realize infrared
c
ommunication between computer and peripheral equipment that comply with IrDA specifications.
6. Parameter
6.1 Absolute maximum rating (Critical o
r exceeding absolute maximum can cause permanent damage to device)
Name Parameter Description Min. Max. Units
CH340G/CH340T/CH340R -40 85
℃
TA Ambient temperature
CH340C/CH340E/CH340B -20 70
℃
TS Storage temperature -55 125
℃
VCC Supply Voltage(VCC connects to power, GND to ground) -0.5 6.0 V
VIO The voltage of input or output pin -0.5 VCC+0.5 V