How to convert levels in DSP system design?

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How to convert levels in DSP system design? [Copy link]

1) It is inevitable that there is a 5V/3.3V mixed power supply phenomenon in the DSP system; 2) For DSPs with 3.3V I/O power supply, the input signal level is not allowed to exceed the power supply voltage of 3.3V; 3) The high level of the output signal of a 5V device can reach 4.4V; 4) Long-term abnormal operation will damage the DSP device; 5) The output signal level generally does not need to be changed Methods of level conversion 1, Bus Transceiver: Common devices: SN74LVTH245A (8-bit), SN74LVTH16245A (16-bit) Features: 3.3V power supply, direction control required, delay: 3.5ns, drive: -32/64mA, input tolerance: 5V Application: drive of data, address and control bus 2.Bus Switch Common devices: SN74CBTD3384 (10 bits), SN74CBTD16210 (20 bits) Features: 5V power supply, no direction control required, delay: 0.25ns, no increase in driving capability Application: Suitable for applications with flexible signal direction and single load, such as level conversion of peripheral signals such as McBSP 3.2-to-1 switcher (1 of 2 Multiplexer) Common devices: SN74CBT3257 (4-bit), SN74CBT16292 (12-bit) Features: 2-to-1, 5V power supply, no direction control required, delay: 0.25ns, no increase in driving capability Application: Suitable for applications with multi-channel switching signals and level conversion, such as dual-channel multiplexed McBSP 4, CPLD 3.3V power supply, but the input tolerance is 5V, and the delay is large: >7ns, suitable for a small number of input signals with low delay requirements 5, resistor voltage divider 10KΩ and 20KΩ series voltage divider, 5V×20÷(10+20)≈3.3V