ST16C552
ST16C552A
DUAL UART WITH 16-BYTE FIFO AND
PARALLEL PRINTER PORT
December 2003
DESCRIPTION
The ST16C552/ST16C552A (552/552A) 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 552/552A provides enhanced UART functions with 16 byte FIFOs, 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 552/552A is available in a 68 pin PLCC package. The 552/552A is compatible
with the 16C450 and 16C550. The difference between the ST16C552 and ST16C552A is the logic state of the
printer port, INTP interrupt. The INTP interrupt is active high (logic 1) on the ST16C552 whereas INTP is active
low (logic 0) on the ST16C552A part when the interrupt latch mode is selected. The 552/552A is fabricated in an
advanced CMOS process with power down mode to reduce the power consumption. The 552A does not support
the power down mode.
PLCC Package
FEATURES
Added features in device revision and newer:
5V Tolerant Inputs
Pin to pin and functional compatible to ST16C452/
TXB 10 60 INTB
452PS, TL16C552
-DTRB 11 59 INTP
2.97 to 5.5 volt operation -RTSB 12 58 -SLCTIN
-CTSB 13 57 INIT
Software compatible with INS8250, NS16C550
D0 14 56 -AUTOFDXT
1.5 Mbps transmit/receive operation (24MHz)
D1 15 55 -STROBE
16 byte transmit FIFO
D2 16 54 GND
D3 17 53 PD0
16 byte receive FIFO with error flags
ST16C552CJ68
18 52 PD1
D4
ST16C552ACJ68
Independent transmit and receive control
D5 19 51 PD2
Modem and printer status registers
D6 20 50 PD3
D7 21 49 PD4
UART port and printer port Bi-directional
-TXRDYA 22 48 PD5
Printer port direction set by single control bit or 8 bit
VCC 23 47 PD6
pattern (AA/55)
24
-RTSA 46 PD7
Modem control signals (-CTS, -RTS, -DSR, -DTR,
-DTRA 25 45 INTA
TXA 26 44 RDOUT
-RI, -CD)
Programmable character lengths (5, 6, 7, 8)
Even, odd, or no parity bit generation and detection
TTL compatible inputs, outputs
Power down mode
ORDERING INFORMATION
Part number Pins Package Operating temperature Device Status
ST16C552CJ68 68 PLCC 0 C to + 70 C Active
ST16C552ACJ68 68 PLCC 0 C to + 70 C Active
ST16C552IJ68 68 PLCC -40 C to + 85 C Active
ST16C552AIJ68 68 PLCC -40 C to + 85 C Active
Rev. 3.40
EXAR Corporation, 48720 Kato Road, Fremont, CA 94538 (510) 668-7000 FAX (510) 668-7017
GND 27 9 -RXRDYA
-CTSA 28 8 -CDB
-CDA 29 7 GND
-RIA 30 6 -RIB
-DSRA 31 5 -DSRB
-CSA 32 4 CLK
A2 33 3 -CSB
A1 34 2 GND
A0 35 1 BIDEN
-IOW 36 ACK
68
-IOR 37 67 PE
-CSP 38 66 -BUSY
-RESET 39 65 SLCT
VCC 40 64 VCC
RXA 41 63 ERROR
-TXRDYB 42 62 RXB
INTSEL 43 61 -RXRDYBST16C552/552A
Figure 1, Block Diagram
Transmit Transmit
FIFO Shift TX A,B
D0-D7
Registers Register
-IOR
-IOW
-RESET
Receive Receive
BIDEN
FIFO Shift RX A,B
Registers Register
Printer
PD0-PD7
Data
Ports
-STROBE
INIT
A0-A2
-AUTOFDX
-CSA
Printer
-SELCTIN
-CSB
Control
-CSP
Logic
PE, SELECT
-BUSY, -ACK
ERROR
-DTR A,B
-RTS A,B
Modem
-CTS A,B
Control
Clock
INT A,B
-RI A,B
Logic
&
INTP
-CD A,B
Baud Rate
-RXRDY
-DSR A,B
Generator
-TXRDY
Rev. 3.40
2
Interrupt Register Data bus
Control Select &
Logic Logic Control Logic
Inter Connect Bus Lines
&
Control signals
CLK