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PDF CH340 Data sheet ( Hoja de datos )
| Número de pieza | CH340 | |
| Descripción | USB to Serial Chip | |
| Fabricantes | ETC | |
| Logotipo |  |
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 1. USB to Serial Chip (CH340G)  Hay una vista previa y un enlace de descarga de CH340 (archivo pdf) en la parte inferior de esta página. Total 11 Páginas | ||
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The DataSheet of CH340 (the first)
1
USB to serial chip CH340
English DataSheet
Version: 1D
http://wch.cn
1. Introduction
CH340 is a USB bus convert chip and it can realize USB convert to serial interface, USB convert to
IrDA infrared or USB convert to printer interface.
In serial interface mode, CH340 supplies common MODEM liaison signal, used to enlarge
asynchronous serial interface of computer or upgrade the common serial device to USB bus directly. More
detail about USB convert to printer interface please referring to the second manual CH340DS2.
In infrared mode, add infrared transceiver to CH340 can compose USB infrared adapter, realize SIR
infrared communication.
Computer
or other
USB host
USB
CH340
convert
chip
UART/RS232/IrDA infrared SIR
parallel printer to USB printer
2. Features
● Full speed USB device interface, conforms to USB Specification Version 2.0, only needs crystal and
capacitance external.
● Emulate standard serial interface, used to upgrade the former peripheral device, or add excess serial
interface through USB.
● Totally compatible with serial application program in computer endpoint Windows operation system.
● Hardware full duplex serial interface, set transceiver buffer, supports communication baud rate varies
from 50bps to 2Mbps.
● Supports common MODEM liaison signal RTS, DTR, DCD, RI, DSR and CTS.
● Through adding level converter equipment to supply RS232, RS485, RS422 and other interface.
● Supports IrDA criterion SIR infrared communication, supports baud rate varies from 2400bps to
115200bps.
● For it is through USB converts to serial interface, only compatible with application layer not totally.
● Software compatible with CH341, using drive of CH341 directly.
● Support 5V and 3.3V source voltage.
● Supply SSOP-20 package without lead, compatible with RoHS.
1 page  
The DataSheet of CH340 (the first)
5
7. Application
7.1. USB convert 9-wire serial interface (the following image)
The following image is using CH340T to realize USB convert RS232 serial interface. CH340 supplies
common serial interface signal and MODEM signal, changes TTL serial interface to RS232 serial interface
through level convert circuit U8. Endpoint P11 is DB9 needle, the pin and its function is the same as
common nine needles serial interface of computer. The similar with U8 is MAX213/ADM213/SP213 etc.
Take the U8 and C46/C47/C48.C49/C40 out when only realize USB convert to TTL serial interface.
The signal wire in the image can only connect RXD、TXD and public ground, the other signal wire can
suspend when not use.
P2 is USB endpoint. USB bus contains a pair of 5V power wire and a pair of data signal wire. Usually,
the +5V power wire is red, the black is ground. D+ signal wire is green and the D- signal wire is white. The
max source current of USB bus is up to 500mA. In generally, CH340 and low power exhaust USB product
can directly use the 5V power supplied by USB bus. If the USB product supplies stock power by other
manner, CH340 must use this stock power. If the USB bus power and stock power are necessary at the same
time, connect a 1Ω resistor between USB bus 5V power wire and USB product 5V stock power, and connect
the two power wires’ ground wire directly.
The capacitance of C8 varies from 4700pF to 0.02uF, used to internal power node decoupling of CH340.
The C9 is 0.1uF, used to external power decoupling. Crystal X2、capacitance C6 and C7 are used to clock
surge circuit. The X2 is 12MHz quartz crystal, C6 and C7 are monolithic or high frequency stoneware
capacitance with 22pF. If X2 is ceramic with low cost, C6 and C7 must use the recommend value of crystal
manufacturer and generally is 47pF.
When designing the PCB, pay much attention to some notes: decoupling capacitance C8 and C9 must
keep near to connection pin of CH340; makes sure D+ and D- are parallel and supply ground net or pour
copper beside them to decrease the disturbance from outside signal; the relevant signal between XI and XO
must be kept as short as possible. In order to lessen the high frequency disturbance, play ground net or pour
copper to the relative equipment.
7.2. USB convert RS232 serial interface (the following image)
The image is USB converts to basic and common three wires RS232 serial interface, and U5 is
MAX232/ICL232/SP232 etc.
5 Page 
The DataSheet of CH340 (the second)
5
keep near to connection pin of CH340; makes sure D+ and D- are parallel and supply ground net or pour
copper beside them to decrease the disturbance from outside signal; the relevant signal between XI and XO
must be kept as short as possible. In order to lessen the high frequency disturbance, play ground net or pour
copper to the relative equipment.
11 Page | ||
| Páginas | Total 11 Páginas | |
| PDF Descargar | [ Datasheet CH340.PDF ] | |
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