EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 • (510) 668-7000 • FAX (510) 668-7017
ST16C550
Rev. 5.01
PLCC Package
UART WITH 16-BYTE FIFO’s
6
5
4
3
2
1
44
43
42
41
40
7
8
9
10
11
12
13
14
15
16
17
39
38
37
36
35
34
33
32
31
30
29
18
19
20
21
22
23
24
25
26
27
28
D5
D6
D7
RCLK
RX
N.C.
TX
CS0
CS1
-CS2
-BAUDOUT
RESET
-OP1
-DTR
-RTS
-OP2
N.C.
INT
-RXRD
Y
A0
A1
A2
D4
D3
D2
D1
D0
N.C
.
VCC
-RI
-CD
-DSR
-CT
S
XTAL1
XTAL2
-IOW
IOW
GND
N.C.
-IOR
IOR
-DDIS
-
TXRDY
-AS
ST16C550CJ44
April 2005
GENERAL DESCRIPTION
The ST16C550 (550) is a universal asynchronous re-
ceiver and transmitter with 16 byte transmit and receive
FIFO. It operates at 2.97 to 5.5 volts. A programmable
baud rate generator can select transmit and receive
clock rates from 50 bps to 1.5 Mbps.
The ST16C550 is an improved version of the NS16C550
UART with higher operating speed and lower access
time. The ST16C550 on board status registers provides
the error conditions, type and status of the transfer
operation being performed. Included is complete MO-
DEM control capability, and a processor interrupt
system that may be software tailored to the user’s
requirements. The ST16C550 provides internal loop-
back capability for on board diagnostic testing.
The ST16C550 is available in 40 pin PDIP, 44 pin PLCC,
and 48 pin TQFP packages. It is fabricated in an
advanced CMOS process to achieve low drain power
and high speed requirements.
FEATURES
• Pin to pin and functionally compatible to the Industry
Standard 16C550
• 2.97 to 5.5 volt operation
• 24MHz clock operation at 5V
• 16MHz clock operation at 3.3V
• 16 byte transmit FIFO
• 16 byte receive FIFO with error flags
• Full duplex operation
• Transmit and receive control
• Four selectable receive FIFO interrupt trigger levels
ORDERING INFORMATION
Part number Package Operating temperature Device Status
ST16C550CP40 40-Lead PDIP 0° C to + 70° C Active. See the ST16C550CQ48 for new designs.
ST16C550CJ44 44-Lead PLCC 0° C to + 70° C Active
ST16C550CQ48 48-Lead TQFP 0° C to + 70° C Active
ST16C550IP40 40-Lead PDIP -40° C to + 85° C Active. See the ST16C550IQ48 for new designs.
ST16C550IJ44 44-Lead PLCC -40° C to + 85° C Active
ST16C550IQ48 48-Lead TQFP -40° C to + 85° C Active
• Standard modem interface
• Compatible with ST16C450
• Low operating current ( 1.2mA typ.)
ST16C550
2
Rev. 5.01
48 Pin TQFP Package 40 Pin DIP Package
Figure 1, PACKAGE DESCRIPTION, ST16C550
48
47
46
45
44
43
42
41
40
39
38
37
1
2
3
4
5
6
7
8
9
10
11
12
36
35
34
33
32
31
30
29
28
27
26
25
13
14
15
16
17
18
19
20
21
22
23
24
N.C.
D5
D6
D7
RCL K
N.C.
RX
TX
CS0
CS1
-CS2
-
BAUDOUT
N.C.
XTAL1
XTAL2
-IOW
IOW
GND
-IOR
IOR
N.C.
-DDIS
-TXRDY
-AS
N.C.
RESET
-OP1
-DTR
-RTS
-OP2
INT
-RXRD
Y
A0
A1
A2
N.C.
N.C
.
D4
D3
D2
D1
D0
VCC
-RI
-CD
-DS
R
-CT
S
N.C
.
ST16C550CQ48
1
2
3
4
5
6
7
8
9
10
11
12
13
14
15
16
17
18
19
20
40
39
38
37
36
35
34
33
32
31
30
29
28
27
26
25
24
23
22
21
D0
D1
D2
D3
D4
D5
D6
D7
RCLK
RX
TX
CS0
CS1
-CS2
-
BAUDOUT
XTAL1
XTAL2
-IOW
IOW
GND
VCC
-RI
-CD
-DSR
-CTS
RESET
-OP1
-DTR
-RTS
-OP2
INT
-RXRD
Y
A0
A1
A2
-AS
-TXRD
Y
-DDIS
IOR
-IOR
ST16C550CP40