EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 • (510) 668-7000 • FAX (510) 668-7017
ST16C452
ST16C452PS
PLCC Package
DUAL UART WITH PARALLEL
PRINTER PORT
March 2004
DESCRIPTION
The ST16C452/ST16C452PS (452/452PS) is a dual universal asynchronous receiver and transmitter (UART)
with an added bi-directional parallel port that is directly compatible with a CENTRONICS type printer. The parallel
port is designed such that the user can configure it as general purpose I/O interface, or for connection to other
printer devices. The 452/452PS provides enhanced UART functions, a modem control interface, and data rates
up to 1.5Mbps. Onboard status registers provide the user with error indications and operational status. The system
interrupts and control may be tailored to meet user requirements. An internal loop-back capability allows onboard
diagnostics. A programmable baud rate generator is provided to select transmit and receive clock rates from 50
bps to 1.5 Mbps. The 452/452PS is available in a 68 pin PLCC package. The 452/452PS is compatible with the
16C450. The 452 is available in two versions, the ST16C452 and the ST16C452PS. The ST16C452 provides
single hardware pin to control the printer port data direction while the 452PS provides an additionally software
control bit to control the printer port data direction to become compatible PS/2 operating system.
The 452/452PS is fabricated in an advanced CMOS process with low power consumption.
FEATURES
Added features in devices with top mark date code of
"F2 YYWW" and newer:
• 5V Tolerant Inputs
• Pin to pin and functional compatible to TL16C452
• 2.97 to 5.5 volt operation
• Software compatible with ST16C450, NS16C450
• 1.5 Mbps transmit/receive operation (24MHz)
• Independent transmit and receive control
• Modem and printer status registers
• UART port and printer port Bi-directional
• Printer port direction set by single control bit or 8 bit
pattern (AA/55)
• Modem control signals (-CTS, -RTS, -DSR, -DTR,
-RI, -CD)
• Programmable character lengths (5, 6, 7, 8)
• Even, odd, or no parity bit generation and detection
• Internal loop-back diagnostics
• TTL compatible inputs, outputs
• Low Power
ORDERING INFORMATION
INTB
INTP
-SLC TIN
INIT
-AUTOFDXT
-STROB E
GND
PD0
PD1
PD2
PD3
PD4
PD5
PD6
PD7
INTA
RDOUT
N.C.
-CDB
GND
-RIB
-DSRB
CLK
-CSB
GND
BIDEN
ACK
PE
-BUSY
SLCT
VCC
ERROR
RXB
N.C.
GND
-CTSA
-CDA
-RIA
-DSRA
-CSA
A2
A1
A0
-I OW
-I OR
-CSP
-RESET
VCC
RXA
N.C.
INTSEL
9
8
7
6
5
4
3
2
1
68
67
66
65
64
63
62
61
10
11
12
13
14
15
16
17
18
19
20
21
22
23
24
25
26
60
59
58
57
56
55
54
53
52
51
50
49
48
47
46
45
44
27
28
29
30
31
32
33
34
35
36
37
38
39
40
41
42
43
ST16C452CJ68
ST16C452CJ68PS
TXB
-DTRB
-RTSB
-CTSB
D0
D1
D2
D3
D4
D5
D6
D7
N.C.
VCC
-RTSA
-DTRA
TXA
Part number Package Operating temperature Device Status
ST16C452CJ68 68-Lead PLCC 0° C to + 70° C Active
ST16C452CJ68PS 68-Lead PLCC 0° C to + 70° C Active
ST16C452IJ68 68-Lead PLCC -40° C to + 85° C Active
ST16C452IJ68PS 68-Lead PLCC -40° C to + 85° C Active
Rev. 3.20
2
ST16C452/452PS
Rev. 3.20
Figure 1, Block Diagram
D0-D7
-IOR
-IOW
-RESET
BIDEN
A0-A2
-CSA
-CSB
-CSP
I
NT A,B
INTP
-D TR A,B
-RT S A,B
-CT S A,B
-RI A,B
-CD A ,B
-DSR A,B
TX A,B
RX A,B
Data bus
&
Control Logic
Register
Select
Logic
Modem
Control
Logic
Interrupt
Control
Logic
Transmit
Holding
Registers
Transmit
Shift
Register
Receive
Holding
Registers
Receive
Shift
Register
Inter Connect Bus Lines
&
Control signals
Clock
&
Baud Rate
Gen e rator
CLK
Printer
Data
Ports
PD0-PD7
Printer
Control
Logic
-STROBE
INIT
-AUTOFDX
-SELCTIN
PE, SELECT
-B U SY , -AC K
ERROR