參數資料
| 型號： | XR16C854IQ-F |
| 廠商： | Exar Corporation |
| 文件頁數： | 5/53頁 |
| 文件大?。?/td> | 0K |
| 描述： | IC UART FIFO 128B QUAD 100QFP |
| 標準包裝： | 66 |
| 特點： | * |
| 通道數： | 4，QUART |
| FIFO's： | 128 字節(jié) |
| 規(guī)程： | RS232，RS485 |
| 電源電壓： | 2.97 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： | 100-BQFP |
| 供應商設備封裝： | 100-QFP（14x20） |
| 包裝： | 托盤 |
| 其它名稱： | 1016-1652 XR16C854IQ-F-ND |
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XR16C854/854D
13
REV. 3.1.0
2.97V TO 5.5V QUAD UART WITH 128-BYTE FIFO
2.9
Crystal Oscillator or External Clock Input
The 854 includes an on-chip oscillator (XTAL1 and XTAL2) to produce a clock for all four UART sections in the
device. The CPU data bus does not require this clock for bus operation. The crystal oscillator provides a
system clock to the Baud Rate Generators (BRG) section found in each of the UART. XTAL1 is the input to the
oscillator or external clock buffer input with XTAL2 pin being the output. For programming details, see
“Programmable Baud Rate Generator.”
FIGURE 5. TYPICAL OSCILATOR CONNECTIONSL
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 Figure 5). Typical standard crystal
frequencies are: 1.8432, 3.6864, 7.3728, 14.7456, 18.432, and 22.1184 MHz. Alternatively, an external clock
can be connected to the XTAL1 pin to clock the internal baud rate generator for standard or custom rates.
Typical oscillator connections are shown in Figure 5. For further reading on oscillator circuit please see
application note DAN108 on EXAR’s web site.
2.10
Programmable Baud Rate Generator
Each UART has its own Baud Rate Generator (BRG) with a prescaler. The prescaler is controlled by a
software bit in the MCR register. The MCR register bit-7 sets the prescaler to divide the input crystal or external
clock by 1 or 4. The clock output of the prescaler goes to the BRG. The BRG further divides this clock by a
programmable divisor between 1 and (216 -1) to obtain a 16X sampling rate clock of the serial data rate. The
sampling rate clock is used by the transmitter for data bit shifting and receiver for data sampling.
Table 6 shows the standard data rates available with a 14.7456 MHz crystal or external clock at 16X sampling
rate. When using a non-standard frequency crystal or external clock, the divisor value can be calculated for
DLL/DLM with the following equation.
TABLE 5: TXRDY# AND RXRDY# OUTPUTS IN FIFO AND DMA MODE FOR CHANNELS A-D
PINS
FCR BIT-0=0
(FIFO DISABLED)
FCR BIT-0=1 (FIFO ENABLED)
FCR Bit-3 = 0
(DMA Mode Disabled)
FCR Bit-3 = 1
(DMA Mode Enabled)
RXRDY#
0 = 1 byte
1 = no data
0 = at least 1 byte in FIFO
1 = FIFO empty
1 to 0 transition when FIFO reaches the trigger
level, or timeout occurs.
0 to 1 transition when FIFO empties.
TXRDY#
0 = THR empty
1 = byte in THR
0 = FIFO empty
1 = at least 1 byte in FIFO
0 = FIFO has at least 1 empty location.
1 = FIFO is full.
divisor (decimal) = (XTAL1 clock frequency / prescaler) / (serial data rate x 16)
C 1
2 2 -47 p F
C 2
2 2 -4 7 pF
1 4 .7 45 6
M H z
X T A L1
X T A L2
R = 30 0 K to 40 0 K
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相關代理商/技術參數 |
參數描述 |
|---|---|
| XR16C854IQTR-F | 功能描述:UART 接口集成電路 UART RoHS:否 制造商:Texas Instruments 通道數量:2 數據速率: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 |
| XR16C854IV | 制造商:Exar Corporation 功能描述: |
| XR16C854IV-F | 功能描述:UART 接口集成電路 UART RoHS:否 制造商:Texas Instruments 通道數量:2 數據速率: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 |
| XR16C854IV-F | 制造商:Exar Corporation 功能描述:IC QUAD UART 2MBPS 5.5V 64-LQFP |
| XR16C854IVTR-F | 功能描述:UART 接口集成電路 UART RoHS:否 制造商:Texas Instruments 通道數量:2 數據速率: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 |
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