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EPM240 数据表(PDF) 52 Page - Altera Corporation |
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EPM240 数据表(HTML) 52 Page - Altera Corporation |
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52 / 88 page  4–2 Chapter 4: Hot Socketing and Power-On Reset in MAX II Devices Hot Socketing Feature Implementation in MAX II Devices MAX II Device Handbook © October 2008 Altera Corporation I/O Pins Remain Tri-Stated during Power-Up A device that does not support hot-socketing may interrupt system operation or cause contention by driving out before or during power-up. In a hot socketing situation, the MAX II device’s output buffers are turned off during system power-up. MAX II devices do not drive out until the device attains proper operating conditions and is fully configured. Refer to “Power-On Reset Circuitry” on page 4–5 for information about turn-on voltages. Signal Pins Do Not Drive the V CCIO or VCCINT Power Supplies MAX II devices do not have a current path from I/O pins or GCLK[3..0] pins to the V CCIO or VCCINT pins before or during power-up. A MAX II device may be inserted into (or removed from) a system board that was powered up without damaging or interfering with system-board operation. When hot socketing, MAX II devices may have a minimal effect on the signal integrity of the backplane. AC and DC Specifications You can power up or power down the V CCIO and VCCINT pins in any sequence. During hot socketing, the I/O pin capacitance is less than 8 pF. MAX II devices meet the following hot socketing specifications: ■ The hot socketing DC specification is: | I IOPIN | < 300 A. ■ The hot socketing AC specification is: | I IOPIN | < 8 mA for 10 ns or less. 1 MAX II devices are immune to latch-up when hot socketing. If the TCK JTAG input pin is driven high during hot socketing, the current on that pin might exceed the specifications above. I IOPIN is the current at any user I/O pin on the device. The AC specification applies when the device is being powered up or powered down. This specification takes into account the pin capacitance but not board trace and external loading capacitance. Additional capacitance for trace, connector, and loading must be taken into consideration separately. The peak current duration due to power-up transients is 10 ns or less. The DC specification applies when all V CC supplies to the device are stable in the powered-up or powered-down conditions. Hot Socketing Feature Implementation in MAX II Devices The hot socketing feature turns off (tri-states) the output buffer during the power-up event (either V CCINT or VCCIO supplies) or power-down event. The hot-socket circuit generates an internal HOTSCKT signal when either V CCINT or VCCIO is below the threshold voltage during power-up or power-down. The HOTSCKT signal cuts off the output buffer to make sure that no DC current (except for weak pull-up leaking) leaks through the pin. When V CC ramps up very slowly during power-up, VCC may still be relatively low even after the power-on reset (POR) signal is released and device configuration is complete. |
类似零件编号 - EPM240 |
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类似说明 - EPM240 |
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