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CD82C85 数据表(PDF) 5 Page - Intersil Corporation |
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CD82C85 数据表(HTML) 5 Page - Intersil Corporation |
5 / 21 page 301 until the oscillator signal amplitude reaches the X1 Schmitt trigger input threshold voltage and 8192 cycles of the crystal oscillator output are counted by an internal counter. After this count is complete, the stopped outputs (CLK, CLK50, PCLK, and OSC) start cleanly with the proper phase rela- tionships. Typically, any input signal which meets the START input tim- ing requirements can be used to start the 82C85. In many cases, this would be the INT output from an 82C59A CMOS Priority Interrupt Controller (See Figure 1). This output, which is active high, can be connected to both the 82C85 START pin and to the appropriate interrupt request input on the microprocessor. When the INT output becomes active, the oscillator/clock cir- cuit on the 82C85 will restart. Upon completion of the appro- priate restart sequence, the CLK signal to the CPU will become active. The CPU can then respond to the still pend- ing interrupt request. If the 82C59A/82C85 restart combination is used in conjunc- tion with an 82C55A STOP control, the 82C55A must be ini- tialized prior to the 82C59A after reset. The 82C59A interrupt output is driven high at reset, causing the 82C85 to remain in the START mode regardless of the state of the S2/STOP input. This will avoid stopping the 82C85 due to negative transitions on the S2/STOP input which may occur during a mode change on the 82C55A or during the opera- tion of any peripheral I/O device prior to initialization. Another method of insuring proper operation of the START function upon reset or system initialization is to bias the S2/STOP input low with an external pull-down resistor. The S2/STOP input will remain low until driven high by the 82C55A port pin or by external logic. This insures that the 82C85 STOP command (HHH prior to LHH requirement on the status inputs) will not be satisfied. To minimize power dissipation in this case (using a pulldown resistor), the S2/STOP input should be normally LOW and pulsed HIGH to develop the necessary HHH-to-LHH STOP sequence. In this manner, the output driving the S2/STOP input will be normally LOW and will not be driving to the opposite state of the pull-down resistor. Fast Mode The most common operating mode for a system is the FAST mode. In this mode, the 82C85 operates at the maximum fre- quency determined by the main oscillator or EFI frequency. 82C59A 82C85 START CLK S0 S1 S2/STOP SLO/FST 80C86/88 INTR CLK PA0 PA1 82C55A INT VCC FIGURE 1. CMOS PERIPHERAL CONTROL OF 82C85 STOP, START AND SLOW/FAST OPERATIONS TABLE 2. TYPICAL SYSTEM POWER SUPPLY CURRENT FOR STATIC CMOS OPERATING MODES FAST SLOW STOP-CLOCK STOP-OSC CPU Frequency 5MHz 20 KHz DC DC XTAL Frequency 15MHz 15MHz 15MHz DC ICC 82C85 24.7mA 16.9mA 14.1mA 24.4mA 80C88 23.8mA 173.0mA 106.6mA 106.6mA 82C82 1.7mA 6.5mA 1.0mA 1.0mA 82C86 1.4mA 14.0mA 1.0mA 1.0mA 82C88 3.5mA 14.3mA 3.8mA 3.8mA 82C52 151.2mA 72.0mA 1.0mA 1.0mA 82C54 943.0mA 915.0mA 3.5mA 1.0mA 82C55A 3.2mA 1.2mA 1.0mA 1.0mA 82C59A 580.0mA 520.0mA 1.0mA 1.0mA 74HCXX + other 2.9mA 10.0mA 90.0mA 90.0mA HM-6516 820.0mA 32.0mA 1.9mA 1.9mA HM-6616 6.3mA 52.5mA 12.0mA 12.0mA Total 66.8mA 18.9mA 14.3mA 244.7mA All measurements taken at room temperature, VCC = +5.0V. Power supply current levels will be dependent upon system configuration and frequency of operation. 82C85 |
类似零件编号 - CD82C85 |
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类似说明 - CD82C85 |
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