XR16V794IV-0B-EVB Exar Corporation, XR16V794IV-0B-EVB Datasheet - Page 7

• Manufacturer Part Number: XR16V794IV-0B-EVB
• Description: Supports V794 64 Ld TQFP,ISA Interface
• Manufacturer: Exar Corporation

Specifications of XR16V794IV-0B-EVB

• Design Resources: XR17V798/794 Eval Board Schematic
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

REV. 1.0.1
The INT# interrupt output changes according to the operating mode and enhanced features setup.
and 3
The 794 includes an on-chip oscillator. The crystal oscillator provides the system clock to the Baud Rate
Generators (BRG) in each of the 4 UARTs, the 16-bit general purpose timer/counter and internal logics. XTAL1
is the input to the oscillator or external clock buffer input with XTAL2 pin being the output. For programming
details, see
The on-chip oscillator is designed to use an industry standard microprocessor crystal (parallel resonant,
fundamental frequency with 10-22 pF capacitance load, ESR of 20-120 ohms and 100ppm frequency
tolerance) connected externally between the XTAL1 and XTAL2 pins (see
clock can be connected to the XTAL1 pin to clock the internal 4 baud rate generators for standard or custom
rates. The typical oscillator connections are shown in
see application note DAN108 on EXAR’s web site.
2.4
2.5
summarize the operating behavior for the transmitter and receiver.
INT# Ouput
CRYSTAL OSCILLATOR / BUFFER
Auto RS485
“Section 2.6, Programmable Baud Rate Generator with Fractional Divisor” on page
Mode
YES
NO
HIGH = no data
LOW = 1 byte
HIGH PERFORMANCE 2.25V TO 3.6V QUAD UART WITH FRACTIONAL BAUD RATE
HIGH = a byte in THR
LOW = THR empty
HIGH = a byte in THR
LOW = transmitter empty
(FIFO D
FCR B
(FIFO D
F
FCR B
IGURE
T
ABLE
T
IT
ISABLED
ABLE
-0 = 0
IT
ISABLED
3. T
-0 = 0
2: INT# P
3: INT# P
YPICAL OSCILLATOR CONNECTIONS
)
22-47pF
XTAL1
)
C1
IN
R=300K to 400K
HIGH = FIFO above trigger level
LOW = FIFO below trigger level or FIFO empty
HIGH = FIFO above trigger level
LOW = FIFO below trigger level or transmitter empty
HIGH = FIFO below trigger level
LOW = FIFO above trigger level
IN
O
24 MHz
O
PERATION FOR
PERATION
Figure
7
3. For further reading on oscillator circuit please
(FIFO E
22-47pF
FCR B
XTAL2
F
C2
OR
T
RANSMITTER
R
(FIFO E
FCR B
IT
NABLED
ECEIVER
-0 = 1
Figure
IT
NABLED
)
-0 = 1
)
3). Alternatively, an external
XR16V794
8.
Table 2