The DataSheet of CH341 (the first)

3

Package shape

Width of plastic

Pitch of Pin

Instruction of package

Ordering type

SOP-28

7.62mm 300mil

1.27mm 50mil

Small outline package of 28-pin

CH341A

SSOP-20

5.30mm 209mil

0.65mm 25mil Shrink small outline package of 20-pin

CH341T

SSOP-20

5.30mm 209mil

0.65mm 25mil Shrink small outline package of 20-pin

CH341H

Note: CH341T is only used to USB convert to serial interface or USB convert to 2-wire interface,

CH341H is only used to USB convert to 4-wire interfaces etc. (such as SPI)

4. Pins

4.1.General explanation

The detail function of CH341 is decided by function configuration after reset. The same pin may have

different define under different function.

CH341T and CH341H adopts SSOP-20 package, the simple vision of CH341A, the pins with same pin

name have the same function of them. The multiply VCC pins parallel connect as VCC and multiply GND

pins parallel connect as GND in CH341T and CH341H.

4.2.Standard public pins

Pin No.

341A 341T 341H

Pin Name

Pin Type

Pin Description

28

13,20

20

VCC

POWER

Positive power input port, requires an 0.1uF power

decoupling capacitance

12

11,12

7,18

GND

POWER

Public ground, ground connection for USB bus

9

6

4

V3

POWER

Attachment of VCC input external power while

3.3V;connects of 0.01uF decoupling capacitance

outside while 5V

13

9

8

XI

IN

Input of crystal oscillator, attachment of crystal

and crystal oscillator capacitance external

14

10

9

XO

OUT

Opposite output of crystal oscillator, attachment of

crystal and crystal oscillator capacitance outside

10

7

5

UD+

USB signal

Directly connects to D+ data wire of USB bus

11

8

6

UD-

USB signal

Directly connects to D- data wire of USB bus

1

1

1

ACT#

OUT

After USB device configuration output status, low

active

2

No

2

RSTI

IN

Input of external reset, active with high-level, with

pull-down resistor

24

16

No

SCL

Drain open

Output

Output of chip function configuration, with

pull-up resistor, connect with SCL of serial

EEPROM configuration chip

23

15

No

SDA

drain open

OUT/IN

Input of chip function configuration, with pull-up

resistor, connect with SDA of serial EEPROM

configuration chip