XR17V258IV-F Exar Corporation, XR17V258IV-F Datasheet - Page 35

• Manufacturer Part Number: XR17V258IV-F
• Description: IC UART PCI BUS OCTAL 144LQFP
• Manufacturer: Exar Corporation
• Type: Octal UARTr

Specifications of XR17V258IV-F

• Number Of Channels: 8
• Package / Case: 144-LQFP
• Features: *
• Fifo's: 64 Byte
• Protocol: RS485
• Voltage - Supply: 3.3V, 5V
• With Auto Flow Control: Yes
• With Irda Encoder/decoder: Yes
• With False Start Bit Detection: Yes
• With Modem Control: Yes
• Mounting Type: Surface Mount
• Data Rate: 8 Mbps
• Supply Voltage (max): 3.6 V
• Supply Voltage (min): 3 V
• Supply Current: 4 mA
• Maximum Operating Temperature: + 85 C
• Minimum Operating Temperature: - 45 C
• Mounting Style: SMD/SMT
• Operating Supply Voltage: 3 V to 3.6 V
• No. Of Channels: 8
• Uart Features: Tx/Rx FIFO Counters
• Supply Voltage Range: 3V To 3.6V
• Operating Temperature Range: -40°C To +85°C
• Digital Ic Case Style: LQFP
• No. Of Pins: 144
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant, Lead free / RoHS Compliant

XR17V258
66MHZ PCI BUS OCTAL UART WITH POWER MANAGEMENT SUPPORT
REV. 1.0.2
4.2
Automatic Hardware (RTS/CTS or DTR/DSR) Flow Control Operation
Automatic hardware or RTS/DTR and CTS/DSR flow control is used to prevent data overrun to the local
receiver FIFO and remote receiver FIFO. The RTS#/DTR# output pin is used to request remote unit to
suspend/restart data transmission while the CTS#/DSR# input pin is monitored to suspend/restart local
transmitter. The auto RTS/DTR and auto CTS/DSR flow control features are individually selected to fit specific
application requirement and enabled through EFR bit[7:6] and MCR bit [2] for either RTS/CTS or DTR/DSR
control signals. The auto RTS/DTR function must be started by asserting RTS/DTR# output pin (MCR bit [0] or
bit [1] to logic 1) after it is enabled.
Figure 12
below explains how it works.
Two interrupts associated with RTS/DTR and CTS/DSR flow control have been added to give indication when
RTS/DTR# pin or CTS/DSR# pin is de-asserted during operation. The RTS/DTR and CTS/DSR interrupts must
be first enabled by EFR bit [4], and then enabled individually by IER bits [7:6], and chosen with MCR bit [2].
Automatic hardware flow control is selected by setting bits [7 (CTS): 6 (RTS)] of the EFR register to logic 1. If
CTS# pin transitions from LOW to HIGH indicating a flow control request, ISR bit [5] will be set to logic 1, (if
enabled via IER bit [7:6]), and the UART will suspend TX transmissions as soon as the stop bit of the character
in process is shifted out. Transmission is resumed after the CTS# input returns to LOW, indicating more data
may be sent.
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