Author Topic: FPGA LVCMOS vs LVTTL standards  (Read 1885 times)

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Offline hal9001Topic starter

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FPGA LVCMOS vs LVTTL standards
« on: August 29, 2021, 11:02:13 am »
Vih should be different for 3.3v cmos and ttl. Xilinx Spartan 3 has LVCMOS33 and LVTTL standards that are 3.3V both but Im assuming they have different Vih thresholds. What happens inside the hardware to allow a different Vih to be detected? Is it different set of transistors?

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Online David Hess

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Re: FPGA LVCMOS vs LVTTL standards
« Reply #1 on: August 29, 2021, 11:34:19 am »
LVTTL has the same input thresholds as TTL and they match 3.3 volt CMOS pretty well so they may be using the same receiver for both.
 
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Offline hal9001Topic starter

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Re: FPGA LVCMOS vs LVTTL standards
« Reply #2 on: August 31, 2021, 06:50:24 am »
LVTTL has the same input thresholds as TTL and they match 3.3 volt CMOS pretty well so they may be using the same receiver for both.
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