REV. 1.2.2 26 3.0 CRYSTAL OSCILLATOR / BUFFER The D158 includes an on-chip oscillator (X" />
參數(shù)資料
型號(hào): XR17D158IV-F
廠商: Exar Corporation
文件頁數(shù): 19/73頁
文件大?。?/td> 0K
描述: IC UART PCI BUS OCTAL 144LQFP
產(chǎn)品培訓(xùn)模塊: UART Product Overview
標(biāo)準(zhǔn)包裝: 60
特點(diǎn): *
通道數(shù): 8
FIFO's: 64 字節(jié)
規(guī)程: RS485
電源電壓: 3.3V,5V
帶自動(dòng)流量控制功能:
帶IrDA 編碼器/解碼器:
帶故障啟動(dòng)位檢測功能:
帶調(diào)制解調(diào)器控制功能:
安裝類型: 表面貼裝
封裝/外殼: 144-LQFP
供應(yīng)商設(shè)備封裝: 144-LQFP(20x20)
包裝: 托盤
其它名稱: 1016-1292
XR17D158
xr
UNIVERSAL (3.3V AND 5V) PCI BUS OCTAL UART
REV. 1.2.2
26
3.0 CRYSTAL OSCILLATOR / BUFFER
The D158 includes an on-chip oscillator (XTAL1 and XTAL2). The crystal oscillator provides the system clock
to the Baud Rate Generators (BRG) in each of the 8 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. See Programmable Baud Rate Generator in the UART section for programming details.
The on-chip oscillator is designed to use an industry standard microprocessor crystal (parallel resonant with
10-22 pF capacitance load, 100ppm) connected externally between the XTAL1 and XTAL2 pins (see Figure 9).
Alternatively, an external clock can be connected to the XTAL1 pin to clock the internal 8 baud rate generators
for standard or custom rates. However, for external clock frequencies greater than 24MHz, a 2K pull-up may be
necessary on the XTAL2 output (see Figure 10). Typically, the oscillator connections are shown in Figure 9.
For further reading on oscillator circuit please see application note DAN108 on EXAR’s web site.
FIGURE 9. TYPICAL OSCILLATOR CONNECTIONS
FIGURE 10. EXTERNAL CLOCK CONNECTION FOR EXTENDED DATA RATE
C1
22-47pF
C2
22-47pF
14.7456
MHz
XTAL1
XTAL2
R=300K to 400K
2K
XTAL1
XTAL2
R1
VCC
External Clock
vcc
gnd
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