The DataSheet of CH341 (the first)

9

controlled by CH341. If needing higher-speed to control signal, instead of hardware speed signals.

Assistant pins consist: INT#, OUT#, IN3 and IN7 pin. INT# is a self-defined interrupt request input,

when it detects rising edge of the CLK pin, it will inform computer. OUT# is common low-level active

output signal and its state is determined by computer applied program. These assistant pins are not standard

serial interface and their functions are similar with MODEM communication signals.

CH341 sets separate transceiver buffer internal and supports simplex, semi-duplex and full duplex

asynchronous serial communication. Serial data consist of one low-level starting bit, five to nine data bits

and one or two high-level stopping bit, supports odd checkout/even checkout/flag checkout/blank checkout.

The following communication band rates are supported by CH341:

50,75,100,110,134.5,150,300,600,900,1200,1800,2400,3600,4800,9600,14400,19200,28800,33600,38400,

56000,57600,76800,115200,28000,53600,30400,60800,21600,500000,2000000 and so on. The band rate

error of serial transfer signal is less then 0.3% and the allowance receive signals error is not less then 2%.

In the Windows operation system of computer, driver program of CH341 can simulate standard serial

interface, the most former serial interfaces applied programs are totally compatible without any modify. In

addition, CH341 supports indirectly access to serial EEPROM memory external via standard serial interface

communication mode.

CH341 may use to upgrade serial peripheral equipments or add extra serial interface for computer

through USB bus. External additional of level switch equipment can supply interface such as

RS232,RS485,RS422 and so on.

5.5.Printer interface

The pins of CH341 in printer port can consult interface signals of standard Centronic printer.

CH341 supplies standard USB printer port, conforms to USB specification, IEEE-1284 specification

and Windows operation system. There is no need of driver program in Windows 2000, XP and Vista

operation system of computer. (The truth is that Windows takes driver program itself). All driver program

and applied program supported print are compatible and without and amending.

Printer ports in CH341 support two kinds of interface protocol of USB printer. The two kinds of

interface protocol can be defined in external EEPROM configuration chip and be point out through

configuration description sign in USB device: PROT=1 indicates single directional transfer interface while

PROT=2 indicates bi-directional transfer interface. In default, CH341 selects bi-directional transfer interface

because the data transfer speed is higher than single directional transfer interface according to IEEE-1284

specification.

CH341 printer ports support two kinds data transfer speed: the low speed print mode (standard print

mode) and high-speed print mode. In the low speed mode, CH341 needs to detect answer clock ACK# and

busy signal BUSY of printer. The effective width of data select pulse STB# is 1uS. Data transfer speed is

500KB/S in ideal. In the high-speed mode, the effective width of data select pulse STB# is 0.5uS. Data

transfer speed is 800KB/S in ideal.

CH341 changes various criterions parallel interface printer to USB printer.

6. Parameter

6.1. Absolute maximum rating (Stresses above those listed can cause permanent damage to the device.

Exposure to maximum rated conditions can affect device operation and reliability.)

Name

Parameter note

Min.

Max.

Units

TA

Ambient operating

VCC=5V

-40

85

℃