Tesla MAB399 and MAC01 voltage references review and teardown



Tesla MAB399, MAE299, MAC199 ovenized voltage references

One of EEVBlog members, Gyro, provided photo of LM399 die in this thread, so we can compare both. They are very similar, but not exact clone.

These references were produced by Tesla, a national semiconductor and electronics manufacturer in former Czechoslovakia, Roznov pod Radhostem (It was a company with very long history – established in 1946). Unfortunately, MAC199/MAB399 production didn’t last for long – probably only a couple of years around 1989, then an economic collapse came to Eastern Europe (triggered by collapse of USSR).

The semiconductor fab in Roznov was shut down and it seemed to be the end of production of semiconductors in Czechoslovakia. Hopefully, shortly after the shut down, Tesla semiconductor division was bought by Motorola. The reason was obvious: manufacturing costs were ridiculously low, yet quality was good. Next milestone came in 1999, when Motorola semiconductor division split into two companies – Freescale and On Semiconductor. Both companies are still present in Roznov, although only On Semiconductor has manufacturing facilities there (both silicon wafers and ICs are manufactured in Roznov).

Back to references: I have several pieces of MAC199/MAB399 and there is a difference: MAC199 got a little bit better care since it has gold plated legs.

Schematics of MAB399/MAC199:

For comparison, schematics of LM199/399 from Linear datasheet:

Tesla MAC01 10V voltage reference

MAC01 is a clone of Analog Devices REF01 .

Tesla MAC01


Test results and initial data

var dsvw = d3.dsv(";", "text/plain");
dsvw("/datashort/scan_2002_ref10_nplc10.csv", function(error, data) {
    data.forEach(function(d) {
        d.date = parseDate(d.date);
        d.temp = +(d.ch1 / 0.0002) - 273.15;
        d.ch2 = +(d.ch2 - 6.9241967 ) * 1E6;
        d.ch3 = +(d.ch3 - 6.8754749 ) * 1E6;
        d.ch4 = +(d.ch4 - 7.1905522 ) * 1E6;
        d.ch5 = +(d.ch5 - 7.2799687 ) * 1E6;
        d.ch6 = +(d.ch6 - 7.3355209 ) * 1E6;
        d.ch7 = +(d.ch7 - 7.2061466 ) * 1E6;
        d.ch8 = +(d.ch8 - 7.2229355 ) * 1E6;
        d.ch9 = +(d.ch9 - 7.3331865 ) * 1E6;
        d.ch10= +(d.ch10 - 7.184060) * 1E6;

As code fragment above shows, data is normalized using simple subtract math with reading at 21/04/2016-06:19:26, to show offsets of each reference output in microvolts scale.

Author: Illya Tsemenko
Published: March 25, 2016, 5:20 p.m.
Modified: Oct. 4, 2016, 12:56 p.m.