
MCS7840
USB-2.0 to Four Serial Ports
Page 6
Rev.
1.2
Pin
Name
Type
Functional Description
47
RTS_2_N
Output
Serial Port 2 Request To Send (in serial protocol),
active low.
48
RXD_2
Input
Serial Port 2 Serial Receive Data in from transceiver
or IrDA data in from IrDA detector.
49
GND
K
Power
Core Ground.
50
EXT_CLOCK
Input
Input Clock from external world. In normal operation
mode, clock can be supplied to serial ports and used
for custom BAUD Rate of user’s choice. In test mode,
clock will be the test clock input from external world.
51
Vcc
3IO
Power
Power Pin (D3V3).
52
RI_2_N
Input
Serial Port 2 Ring Indicator, active low.
53
DSR_2_N
Input
Serial Port 2 Data Set Ready (in serial protocol), active
low.
54
DCD_2_N
Input
Serial Port 2 Data Carrier Detect (in serial protocol),
active low.
55
CTS_2_N
Input
Serial Port 2 Clear To Send (in serial protocol), active
low.
56
TXD_3
Output
Serial Port 3 Transmit Data out to transceiver, or IrDA
data out to IR LED.
57
DTR_3_N
Output
Serial Port 3 Data Terminal Ready (in serial protocol),
active low.
58
RTS_3_N
Output
Serial Port 3 Request To Send (in serial protocol),
active low.
59
RXD_3
Input
Serial Port 3 Serial Receive Data in from transceiver,
or IrDA data in from IrDA detector.
60
RI_3_N
Input
Serial Port 3 Ring Indicator, active low.
61
DSR_3_N
Input
Serial Port 3 Data Set Ready (in serial protocol), active
low.
62
DCD_3_N
Input
Serial Port 3 Data Carrier Detect (in serial protocol),
active low.
63
CTS_3_N
Input
Serial Port 3 Clear To Send (in serial protocol), active
low.
64
Vcc
K
Power
Power Pin (1.8V)