XR16C854 Datasheet, PDF (10/51 Pages) Exar Corporation – QUAD UART WITH RX/TX FIFO COUNTERS,128-BYTE FIFO

XR16C854
SYMBOL DESCRIPTION
Symbol
Pin
Signal
68 100 64 type
Pin Description
sets provide both the combined wire “or’ed” output and
individual channel TXRDY-A-D outputs. TXRDY A-D is
discussed in a following paragraph For 64/68 pin packages,
individual channel TX status can be read by examining
individual internal registers via -CS and A0-A4 pin func-
tions.
-TXRDY A-B
-TXRDY C-D
- 5,25
- 56,81 -
O This function is associated with 100 pin packages only.
These outputs provide the TX FIFO/THR status for indi-
vidual transmit channels (A-D). As such, an individual
channel’s -TXRDY A-D buffer ready status is indicated by
logic 0, i.e., at least one location is empty and available in
the FIFO or THR. This pin goes to a logic 1 when there are
no more empty locations in the FIFO or THR.
VCC
VCC
13 10 4,21
47,64 61,86 35,52 I
Power supply inputs.
XTAL1
35 40 25
I Crystal or External Clock Input - Functions as a crystal input
or as an external clock input. A crystal can be connected
between this pin and XTAL2 to form an internal oscillator
circuit (see figure 8). Alternatively, an external clock can be
connected to this pin to provide custom data rates (see
Baud Rate Generator Programming and optional MIDCLK).
XTAL2
36
41
26
O Output of the Crystal Oscillator or Buffered Clock - (See also
XTAL1). Crystal oscillator output or buffered clock output.
-CD A-B
-CD C-D
9,27 99,32 64,18
43,61 49,83 31,49 I Carrier Detect (active low) - These inputs are associated
with individual UART channels A through D. A logic 0 on this
pin indicates that a carrier has been detected by the modem
for that channel.
-CTS A-B
-CTS C-D
11,25 8,22 2,16
45,59 59,73 33,47 I Clear to Send (active low) - These inputs are associated with
individual UART channels, A through D. A logic 0 on the -
CTS pin indicates the modem or data set is ready to accept
transmit data from the 854. Status can be tested by reading
Rev. 1.00P
10