CD74HC74: CD74HC74 Failure Mode

Phil Baxter

Part Number: CD74HC74
Other Parts Discussed in Thread: SN74LVC1G80

I have a query regarding a possible failure mode of the CD74HC74M D-Type Flip-Flop.

It is proposed to use the flip-flop on the output of a 16MHz Crystal Oscillator to reduce the clock frequency to 8MHz.

However, there is a concern regarding potential failure modes of the CD74HC74M, namely a short circuit between CLK input and the output Q, resulting in an undesirable clock speed.

Do you have any information on the possible failure modes of this device, and specifically whether the short circuit failure described above is feasible? If so, is there an associated failure rate / probability?

Any information you could provide would be greatly appreciated.

over 4 years ago

0 Clemens Ladisch over 4 years ago

Guru 326880 points

It is not possible to make any guarantees about failure modes.

However, typical failures are shorting of input or outputs pins to V_CC or ground. I do not see how it could be possible for only the isolation between CLK and /Q to break down without damage to lots of other internal traces/components. The only plausible failure modes are a 0 Hz output, or a 8 MHz output with a weaker signal.

(The SN74LVC1G80 would be cheaper and smaller.)

0 Phil Baxter over 4 years ago in reply to Clemens Ladisch

Prodigy 10 points

Thanks, this answers my query. Much appreciated.

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CD74HC74: CD74HC74 Failure Mode