Motorola buried zener
A number of older Fluke voltage references used a Motorola buried zener
device as a reference (from what I gather). Anyone know the part number
for that device, have a link to a datasheet, or have specs?
Mike S wrote:
A number of older Fluke voltage references used a Motorola buried
zener device as a reference (from what I gather). Anyone know the part
number for that device, have a link to a datasheet, or have specs?
I thought that they were 1N821 series or similar TC compensated discrete
zeners ( series stack of a zener chip plus one or more forward biased
diodes all in same hermetically sealed package)?
IIRC thats what the manual states.
I have datasheets for most of the Motorola TC zeners if thats what you need.
Bruce
At 09:03 PM 9/12/2009, Bruce Griffiths wrote...
I thought that they were 1N821 series or similar TC compensated
discrete
zeners ( series stack of a zener chip plus one or more forward biased
diodes all in same hermetically sealed package)?
IIRC thats what the manual states.
I have datasheets for most of the Motorola TC zeners if thats what you
need.
No, not the 1N82x series zeners.
These had a zener with the emitter of an NPN transistor against its
cathode (for the tempco offsetting PN junction) in the device, and were
used in the Fluke 731B, 732A, 332B/D, 335, and no doubt more. They are
4 terminal devices. Fluke "ovenized" them.
Fluke service manuals only refer to them with an internal designation.
My understanding is that these were "state of the art" prior to the
National LMx99 (which was in turn followed by the LTZ1000).
Mike S wrote:
At 09:03 PM 9/12/2009, Bruce Griffiths wrote...
I thought that they were 1N821 series or similar TC compensated discrete
zeners ( series stack of a zener chip plus one or more forward biased
diodes all in same hermetically sealed package)?
IIRC thats what the manual states.
I have datasheets for most of the Motorola TC zeners if thats what
you need.
No, not the 1N82x series zeners.
These had a zener with the emitter of an NPN transistor against its
cathode (for the tempco offsetting PN junction) in the device, and
were used in the Fluke 731B, 732A, 332B/D, 335, and no doubt more.
They are 4 terminal devices. Fluke "ovenized" them.
Fluke service manuals only refer to them with an internal designation.
My understanding is that these were "state of the art" prior to the
National LMx99 (which was in turn followed by the LTZ1000).
You mean the ancient Motorola reference amplifiers?
I should also have some data on these.
These were discrete devices in hemetic packages welded together within
an overall 4 lead metal hermetic package.
Depending on the voltage the zener may have had one or more forward
biased diodes connected in series.
Bruce
Bruce Griffiths wrote:
Mike S wrote:
At 09:03 PM 9/12/2009, Bruce Griffiths wrote...
I thought that they were 1N821 series or similar TC compensated discrete
zeners ( series stack of a zener chip plus one or more forward biased
diodes all in same hermetically sealed package)?
IIRC thats what the manual states.
I have datasheets for most of the Motorola TC zeners if thats what
you need.
No, not the 1N82x series zeners.
These had a zener with the emitter of an NPN transistor against its
cathode (for the tempco offsetting PN junction) in the device, and
were used in the Fluke 731B, 732A, 332B/D, 335, and no doubt more.
They are 4 terminal devices. Fluke "ovenized" them.
Fluke service manuals only refer to them with an internal designation.
My understanding is that these were "state of the art" prior to the
National LMx99 (which was in turn followed by the LTZ1000).
You mean the ancient Motorola reference amplifiers?
I should also have some data on these.
These were discrete devices in hemetic packages welded together within
an overall 4 lead metal hermetic package.
Depending on the voltage the zener may have had one or more forward
biased diodes connected in series.
Bruce
The reference amplifier(U2) on A4 reference board circuit in the 732A
appears to be compatible with one of the Motorola 6.8V reference
amplifiers such as the MCA1914N, MCA1924N or MCA1934N.
The only difference between these is the specified operating temperature
range.
If the oven temperature is around 50C then a selected MCA19124N is likely.
They had a maximum voltage change (Iz = 5mA) of 5mV over the 0-75C
operating temperature range.
Reference voltage was 6.8V with a 10% tolerance.
Bruce
At 10:06 PM 9/12/2009, Bruce Griffiths wrote...
The reference amplifier(U2) on A4 reference board circuit in the 732A
appears to be compatible with one of the Motorola 6.8V reference
amplifiers such as the MCA1914N, MCA1924N or MCA1934N.
The only difference between these is the specified operating
temperature
range.
If the oven temperature is around 50C then a selected MCA19124N is
likely.
They had a maximum voltage change (Iz = 5mA) of 5mV over the 0-75C
operating temperature range.
Reference voltage was 6.8V with a 10% tolerance.
That sounds right. That's about 10 ppm/C tempco. Any idea what
Motorola's spec was for long term drift? 732As had a mean drift rate of
~0.5 PPM/yr., according to Fluke (about 4x better than the LTZ1000
spec!), and a tight deviation, both much better than the newer 732Bs .
BTW, these types were used by Fluke at least through the early '90's,
in the early 732Bs, so I don't know that calling them "ancient" is
fair.
Mike S wrote:
At 10:06 PM 9/12/2009, Bruce Griffiths wrote...
The reference amplifier(U2) on A4 reference board circuit in the 732A
appears to be compatible with one of the Motorola 6.8V reference
amplifiers such as the MCA1914N, MCA1924N or MCA1934N.
The only difference between these is the specified operating temperature
range.
If the oven temperature is around 50C then a selected MCA19124N is
likely.
They had a maximum voltage change (Iz = 5mA) of 5mV over the 0-75C
operating temperature range.
Reference voltage was 6.8V with a 10% tolerance.
That sounds right. That's about 10 ppm/C tempco. Any idea what
Motorola's spec was for long term drift? 732As had a mean drift rate
of ~0.5 PPM/yr., according to Fluke (about 4x better than the LTZ1000
spec!), and a tight deviation, both much better than the newer 732Bs .
BTW, these types were used by Fluke at least through the early '90's,
in the early 732Bs, so I don't know that calling them "ancient" is fair.
They vanished from the databooks some time ago, probably in the early 90s.
As far as I can tell there were 2 versions, the original in a hermetic
metal cylindrical outer package (in 1967 zener diode hand book) and
another version with a rectangular plastic over-molded outer package (in
1974 Motorola databook).
Neither datasheet has long term drift specs.
I cant find A181 the only application note I know about on reference
amplifiers.
The only Motorola long term stability data I've seen is for the MZ600
and MZ800 series reference diodes.
The best of these had a stability of 30uV/1000 hours (for the MZ605-
6.2V reference).
The measured instability may be degraded significantly by the
measurement setup used (oil baths standard cells etc).
I would suspect that selected Motorola reference amplifiers had similar
stability.
Bruce