Philips Semiconductors Product data sheet
SC28C94Quad universal asynchronous receiver/transmitter (QUART)
2
2006 Aug 09
DESCRIPTION
The 28C94 quad universal asynchronous receiver/transmitter
(QUART) combines four enhanced Philips Semiconductors
industry-standard UARTs with an innovative interrupt scheme that
can vastly minimize host processor overhead. It is implemented
using Philips Semiconductors’ high-speed CMOS process that
combines small die size and cost with low power consumption.
The operating speed of each receiver and transmitter can be
selected independently at one of eighteen fixed baud rates, a 16X
clock derived from a programmable counter/timer, or an external 1X
or 16X clock. The baud rate generator and counter/timer can
operate directly from a crystal or from external clock inputs. The
ability to independently program the operating speed of the receiver
and transmitter make the QUART particularly attractive for
dual-speed channel applications such as clustered terminal
systems.
Each receiver is buffered with eight character FIFOs (first-in-first-out
memories) and one shift register to minimize the potential for
receiver overrun and to reduce interrupt overhead in interrupt driven
systems. In addition, a handshaking capability is provided to disable
a remote UART transmitter when the receiver buffer is full. (RTS
control)
The 28C94 provides a power-down mode in which the oscillator is
stopped and the register contents are stored. This results in reduced
power consumption on the order of several magnitudes. The
QUART is fully TTL compatible and operates from a single +5V
power supply.
FEATURES
• New low overhead interrupt control
• All commercial parts meet industrial timing and temperature
parameters
• Four Philips Semiconductors industry-standard UARTs
• Eight byte receive FIFO and eight byte transmit FIFO for each
UART
• Programmable data format:
– 5 to 8 data bits plus parity
– Odd, even, no parity or force parity
– 1, 1.5 or 2 stop bits programmable in 1/16-bit increments
• Baud rate for the receiver and transmitter selectable from:
– 23 fixed rates: 50 to 230.4K baud; Non-standard rates to
1.0 M baud
– User-defined rates from the programmable counter/timer
associated with each of two blocks
– External 1x or 16x clock
• Parity, framing, and overrun error detection
• False start bit detection
• Line break detection and generation
• Programmable channel mode
– Normal (full-duplex), automatic echo, local loop back, remote
loopback
• Programmable interrupt priorities
• Identification of highest priority interrupt
• Global interrupt register set provides data from interrupting
channel
• Vectored interrupts with programmable vector format
• IACKN and programmable DTACKN signals
• Built-in baud rate generator with choice of 18 rates
• Four I/O pins per UART for modem controls, clocks, etc.
• Power down mode
• High-speed CMOS technology
• 52-pin PLCC package
• Commercial and industrial temperature ranges available
• On-chip crystal oscillator
• TTL compatible
• Single +5V power supply with low power mode
• Two multifunction programmable 16-bit counter/timers
• 1MHz 16x mode operation
• 10ns data bus release time
• “Watch Dog” timer for each receiver
ORDERING INFORMATION
INDUSTRIAL
PACKAGES
V
CC
= +5 V ±10 %,
T
A
= –40 °C to +85 °C
DWG #
52-Pin Plastic Leaded Chip Carrier (PLCC) Package SC28C94A1A SOT238-2
