参数资料
| 型号： | XR16V798IQ-F |
| 厂商： | Exar Corporation |
| 文件页数： | 9/56页 |
| 文件大小： | 0K |
| 描述： | IC UART FIFO 64B OCTAL 100QFP |
| 标准包装： | 66 |
| 特点： | * |
| 通道数： | 8 |
| FIFO's： | 64 字节 |
| 规程： | RS485 |
| 电源电压： | 2.25 V ~ 3.6 V |
| 带自动流量控制功能： | 是 |
| 带IrDA 编码器/解码器： | 是 |
| 带故障启动位检测功能： | 是 |
| 带调制解调器控制功能： | 是 |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 100-BQFP |
| 供应商设备封装： | 100-QFP（14x20） |
| 包装： | 托盘 |
| 其它名称： | 1016-1647 XR16V798IQ-F-ND |
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XR16V798
17
REV. 1.0.1
HIGH PERFORMANCE 2.25V TO 3.6V OCTAL UART WITH FRACTIONAL BAUD RATE
In the event that the receive buffer is overfilling and flow control needs to be executed, the 798 automatically
sends an Xoff message (when enabled) via the serial TX output to the remote modem. The 798 sends the Xoff-
1,2 characters two character times (= time taken to send two characters at the programmed baud rate) after
the receive FIFO crosses the programmed trigger level (for all trigger tables A-D). To clear this condition, the
798 will transmit the programmed Xon-1,2 characters as soon as receive FIFO is less than one trigger level
below the programmed trigger level (for Trigger Tables A, B, and C) or when receive FIFO is less than the
trigger level minus the hysteresis value (for Trigger Table D). This hysteresis value is the same as the Auto
RTS/DTR Hysteresis value in Table 17. Table 6 below explains this when Trigger Table-B (See Table 14) is
selected.
* After the trigger level is reached, an xoff character is sent after a short span of time (= time required to send 2 characters);
for example, after 2.083ms has elapsed for 9600 baud and 10-bit word length setting.
2.12
Special Character Detect
A special character detect feature is provided to detect an 8-bit character when bit-5 is set in the Enhanced
Feature Register (EFR). When this character (Xoff2) is detected, it will be placed in the FIFO along with normal
incoming RX data. The 798 compares each incoming receive character with Xoff-2 data. If a match exists, the
received data will be transferred to FIFO and ISR bit-4 will be set to indicate detection of special character.
Although the Internal Register Table shows Xon, Xoff Registers with 8 bits of character information, the actual
number of bits is dependent on the programmed word length. Line Control Register (LCR) bits 0-1 defines the
number of character bits, i.e., either 5 bits, 6 bits, 7 bits, or 8 bits. The word length selected by LCR bits 0-1
also determines the number of bits that will be used for the special character comparison. Bit-0 in the Xon, Xoff
Registers corresponds to the LSB bit for the receive character.
2.13
Auto RS485 Half-duplex Control
The auto RS485 half-duplex direction control changes the behavior of the transmitter when enabled by FCTR
bit-5. It asserts RTS# or DTR# (LOW) after a specified delay indicated in MSR[7:4] following the last stop bit of
the last character that has been transmitted. This helps in turning around the transceiver to receive the remote
station’s response. The delay optimizes the time needed for the last transmission to reach the farthest station
on a long cable network before switching off the line driver. This delay prevents undesirable line signal
disturbance that causes signal degradation. When the host is ready to transmit next polling data packet again,
it only has to load data bytes to the transmit FIFO. The transmitter automatically de-asserts RTS# or DTR#
output (HIGH) prior to sending the data. The auto RS485 half-duplex direction control also changes the
transmitter empty interrupt to TSR empty instead of THR empty.
2.14
Infrared Mode
Each UART in the 798 includes the infrared encoder and decoder compatible to the IrDA (Infrared Data
Association) version 1.0. The input pin ENIR conveniently activates all 8 UART channels to start up in the
infrared mode. Note that the ENIR pin is sampled when the RST# input is de-asserted. This global control pin
enables the MCR bit-6 function in every UART channel register. After power up or a reset, the software can
overwrite MCR bit-6 if so desired. ENIR and MCR bit-6 also disable the receiver while the transmitter is
sending data. This prevents echoed data from reaching the receiver. The global activation ENIR pin prevents
the infrared emitter from turning on and drawing large amount of current while the system is starting up. When
the infrared feature is enabled, the transmit data outputs, TX[7:0], would idle at logic zero level. Likewise, the
RX [7:0] inputs assume an idle level of logic zero.
TABLE 6: AUTO XON/XOFF (SOFTWARE) FLOW CONTROL
RX TRIGGER LEVEL
INT PIN ACTIVATION
XOFF CHARACTER(S) SENT
(CHARACTERS IN RX FIFO)
XON CHARACTER(S) SENT
(CHARACTERS IN RX FIFO)
8
8*
0
16
16*
8
24
24*
16
28
28*
24
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相关代理商/技术参数 |
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|---|---|
| XR16V798IQTR-F | 制造商:Exar Corporation 功能描述:UART 8-CH 64Byte FIFO 2.5V/3.3V 100-Pin PQFP T/R |
| XR-1790 | 制造商:未知厂家 制造商全称:未知厂家 功能描述:Audio Schematic |
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| XR17C152CM-0A-EVB | 功能描述:UART 接口集成电路 Supports C152 100 ld TQFP, PCI Interface RoHS:否 制造商:Texas Instruments 通道数量:2 数据速率:3 Mbps 电源电压-最大:3.6 V 电源电压-最小:2.7 V 电源电流:20 mA 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:LQFP-48 封装:Reel |
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