Choosing equivalent zener diodes from Renesas HZ series

[foxie]

I am trying to find modern equivalents for HZ6A1L and HZ162L zener diodes and I would appreciate it if someone could help me find suitable replacements.

According to the datasheet I found, the HZ6A1L has values of VZmin = 5.2V and VZmax = 5.5V. The closest ones I found for that one are BZX55C5V1 and BZX55C5V6 zeners. Which one would be a better fit?

The HZ162L has values between 15.7V and 16.5V. The closest one I found for that one is BZX55C16.

I'd also appreciate it if someone could explain the ranges in voltage ranges in zener diodes and how they impact the choosing of equivalents.

 

[rayma]

Can you post the circuit they are used in?
HZ6A1L is a 5.35V, 2.8%, 0.4W Zener diode.

Typical Vz are 5.1V and 5.6V, as you found.
Generally you should keep the same power rating
so the operating point will be similar.

 

[foxie]

The circuit I am replacing the diodes is from a Japanese class A amplifier, Accuphase P-266.

 

[rayma]

Appears to be a simple clamp circuit, so it won't be too critical.
I would use a 5.1V 400mW or 500mW type. A 5% tolerance should be ok.

Why do you want to replace the Zener diodes?
Or are you building a copy?

 

[foxie]

Thanks! Could you explain what would happen if I used a 500mW 5.1V zener instead of a 400mW? Why is the power of the zener critical? I always assumed that as long as it is greater than the previous voltage it would be fine.

I recently acquired the amplifier with a broken channel, and I am trying to repair/restore it and learn as much as possible about the design.

 

[rayma]

The power rating sets the maximum current.
For a 5.1V 400mW diode, the maximum allowed current is 0.4/5.1 = 0.078A.