解决方案ID: 1394
最后修改: 2006 年3 月09 日
产品类别: 器件
产品领域: 配置(FPGA)
产品子领域: 配置管脚
器件系列: CONFIGURATION DEVICE,FLEX 10K

标题

Can I use an EPC1 to configure two FLEX 10K devices with one FLEX 10K device's VCCIO at 3.3 V and the other FLEX 10K device's VCCIO at 5.0 V?

说明

Yes. You can use an EPC1 to configure two FLEX 10K devices with differing VCCIO (e.g., 5.0 V and 3.3 V). There are two ways to implement this design:

The best approach is to connect VCC of the EPC1 to 5.0 V, and connect the nSTATUS and CONF_DONE pullup resistors to 5.0 V. The FLEX devices are 5.0-V tolerant, and pulling the nSTATUS and CONF_DONE pins to the 5.0-V power supply reduces current consumption in the input buffers.
Connect VCC of the EPC1 to 3.3 V, and connect the nSTATUS and CONF_DONE pullup resistors to 3.3 V. This approach works because 5.0-V signals are not driven to the EPC1 device. However, the current consumption will be slightly higher because the nSTATUS and CONF_DONE inputs are not pulled to the 5.0-V power supply. Because the EPC1 is not 5.0-V tolerant when connected to 3.3-V VCC, Altera does not recommend connecting the EPC1 to 3.3 V and pulling up the signals to 5.0 V.

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