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參數(shù)資料
| 型號： | XR16L2751CMTR-F |
| 廠商： | Exar Corporation |
| 文件頁數(shù)： | 10/50頁 |
| 文件大小： | 0K |
| 描述： | IC UART FIFO 64B DUAL 48TQFP |
| 標準包裝： | 1,500 |
| 特點： | * |
| 通道數(shù)： | 2，DUART |
| FIFO's： | 64 字節(jié) |
| 規(guī)程： | RS232，RS485 |
| 電源電壓： | 2.25 V ~ 5.5 V |
| 帶自動流量控制功能： | 是 |
| 帶IrDA 編碼器/解碼器： | 是 |
| 帶故障啟動位檢測功能： | 是 |
| 帶調制解調器控制功能： | 是 |
| 帶CMOS： | 是 |
| 安裝類型： | 表面貼裝 |
| 封裝/外殼： | 48-TQFP |
| 供應商設備封裝： | 48-TQFP（7x7） |
| 包裝： | 帶卷 (TR) |
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XR16L2751
2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE
REV. 1.2.3
18
2.16
Auto Xon/Xoff (Software) Flow Control
When software flow control is enabled (See Table 16), the 2751 compares one or two sequential receive data
characters with the programmed Xon or Xoff-1,2 character value(s). If receive character(s) (RX) match the
programmed values, the 2751 will halt transmission (TX) as soon as the current character has completed
transmission. When a match occurs, the Xoff (if enabled via IER bit-5) flag will be set and the interrupt output
pin will be activated. Following a suspension due to a match of the Xoff character, the 2751 will monitor the
receive data stream for a match to the Xon-1,2 character. If a match is found, the 2751 will resume operation
and clear the flags (ISR bit-4).
Reset initially sets the contents of the Xon/Xoff 8-bit flow control registers to a logic 0. Following reset the user
can write any Xon/Xoff value desired for software flow control. Different conditions can be set to detect Xon/
Xoff characters (See Table 16) and suspend/resume transmissions. When double 8-bit Xon/Xoff characters
are selected, the 2751 compares two consecutive receive characters with two software flow control 8-bit
values (Xon1, Xon2, Xoff1, Xoff2) and controls TX transmissions accordingly. Under the above described flow
control mechanisms, flow control characters are not placed (stacked) in the user accessible RX data buffer or
FIFO.
In the event that the receive buffer is overfilling and flow control needs to be executed, the 2751 automatically
sends an Xoff message (when enabled) via the serial TX output to the remote modem. The 2751 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 2751 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 Hysteresis value in Table 14. Table 7 below explains this when Trigger Table-B (See Table 11) is
selected.
TABLE 7: 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
* 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 8-bit word length, no parity and 1 stop bit
setting.
2.17
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 2751 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 eight 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 with the LSB bit for the receive character.
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相關代理商/技術參數(shù) |
參數(shù)描述 |
|---|---|
| XR16L2751IM | 制造商:EXAR 制造商全稱:EXAR 功能描述:2.25V TO 5.5V DUART WITH 64-BYTE FIFO AND POWERSAVE |
| XR16L2751IM-F | 功能描述:UART 接口集成電路 UART RoHS:否 制造商:Texas Instruments 通道數(shù)量:2 數(shù)據(jù)速率:3 Mbps 電源電壓-最大:3.6 V 電源電壓-最小:2.7 V 電源電流:20 mA 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:LQFP-48 封裝:Reel |
| XR16L2751IMTR-F | 制造商:Exar Corporation 功能描述:UART 2-CH 64Byte FIFO 2.5V/3.3V/5V 48-Pin TQFP T/R 制造商:Exar Corporation 功能描述:XR16L2751IMTR-F |
| XR16L2752 | 制造商:EXAR 制造商全稱:EXAR 功能描述:2.25V TO 5.5V DUART WITH 64-BYTE FIFO |
| XR16L2752CJ | 制造商:EXAR 制造商全稱:EXAR 功能描述:2.25V TO 5.5V DUART WITH 64-BYTE FIFO |
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