While I was waiting for the parts for LTZ1000 references I had the time to draw circuit and board file for the "LM399 PWM DAC reference" based on the "ION" MickleT. presented over here as a representitive of the russian forum (radiokot.ru).
As far as I understood the original design came from Sergei and is available here:The original design comes from
adver, but sources can be found on
Sergei's google drive.
You can find the source code for two versions:
- 8bit + 14bit fractional
- 8bit + 16bit fractional
and lot's of pictures.
I made some minor changes and put some additional parts into the circuit:
- LT1763 voltage regulator for voltage reference (12V) as well as microcontroller (5V)
- additional resistor divider feedback (for testing purpose at first glance)
- output buffer (LTC2057)
- NTC temperature sensor on one of the ADC pins, to add a temperature compensation scheme
- optical transmitter (TORX1952 or SFH752V) for galvanically insulated data transfer of temperature data and pwm setting to develope temperature compensation algorithm
The board does fit, what a miracle, into a Hammond 1455C801 case.
The boards have been ordered at Elecrow and will arrive soon. In case someone wants to duplicate it and contribute to this reference, attached are the design files (Gerber data). Eagle files on request.
-branadic-