GB Feeler for the Solarfire MCU controlled TEC/LD drivers
Just a heads up on the upcoming TEC/LD-drivers.
It was a long road from a TEC-controller for a beer-keg cooler to these.
Anyone who may be interested, state your interest here. Prices will be posted as soon as the manufacture replies to my price quote request. Of course pricing will greatly depend on demand. I’m not out to get rich here I’m just looking to maybe break even on my development costs and a little something for admin. I don’t know about you all, but I’ve spent a lot of time searching for affordable H-Bridge TEC drivers which could only do a fraction of what these here have to offer. So what do you do when you can't find anything? Build your own. I tried to keep this design as versatile as possible and they perfectly meet up to my needs. I’m always open to suggestions and constructive criticism to make these drivers the best they can be in their class.
For those which may be scared off by the term PID, read this, it will explain and enlighten in a down to earth way. http://igor.chudov.com/manuals/Servo...hout-a-PhD.pdf
A couple of words of wisdom gathered during the development process of these TEC drivers. Even the best drivers in the world will only be as good as their implementation. Mainly meaning, the best placement of the thermal source to be regulated, the placement of the thermal sensor and the placement of the TEC. These three components should be placed as close to one another as possible and equally distanced to one another in order to keep response time and possible thermal oscillation to a minimum. If possible aluminum or copper should be used for the diode mount material; these materials have a low thermal resistance and therefore allow a relative fast extraction/insertion of heat. Keep the mass of the diode mount to a minimum, this keeps the latency of the thermal control loop low and also allows the use of smaller TECs with less thermal energy needed to regulate the thermal loop. Turn your diode so the die carrier will be closest to the TEC. Against what all others may say or do, don’t pump the heat being generated by the TEC into any optic carrying components like the baseplate of your Laser module or Projector. In the short or long run you’re just asking for alignment issues (expanding, contracting, expanding, contracting it's just not good). Put the TEC on top of the diode mount cooling side down with a heat sink on top of the TEC and for god’s sake transport heat away from the rest of the system instead of into it!
Please get the technical details out of the preliminary users guide in the attachment, there are just too many details to post here. It’s just a draft so far, so give me a break.
Offered will be:
1.) Dual channel TEC driver with dual channel fan control and low side LD driver. Board size (96mm x 55mm)
2.) Single channel TEC driver with single channel fan control and low side LD driver. Board size (72mm x 55mm)
3.) Single channel TEC driver. Board size (58mm x 55mm)
4.) Single channel low side LD driver. Board size 31.5mm x 30mm)
5.) 3.3V DPSS version > 20A Dual channel TEC driver with dual channel fan control and low side LD driver. Board size (96mm x 55mm)
Here’s a quick rundown of the specs.
TEC-Driver specs:
PIC18F45K22 (PIC18F46K22) Processor @ 64MHz,
RS232 Interface to GUI,
Single/dual channel PID controlled TEC/LD-Driver,
Independent PSU supply connections for each TEC channel, 12VDC/3500mA + up to 1500mA
for the fan channel @ 12VDC.
Single/dual PID controlled full H-Bridge(s) with 12VDC/±3000mA @ 250kHz with no more than 200mV ripple on the output of each bridge @ 50% duty cycle.
User definable TEC current limiting,
Temperature range 30.0°C – 0.0°C temperature stability of up to ±0.05°C depending on build!
Large temperature transition settling time (full range 30.0°C to 0.0°C and 0.0°C to 30.0°C) 20-40 seconds, depending on build!
All parameters set via user GUI.
LD-Driver specs:
Type: Low side (high side version is coming)
Supply: 6-24VDC/max5A (with standard 3W current-sense resistor), up to 15A with an external sense-resistor 10-25W. FET can dissipate 45W.
Ultra linear up to 300+kHz on 1-20 Ohm loads.
Supply DPSS version: 6-12VDC/max200mA and 3.3VDC max 30A.
Linear up to 100+kHz on a 0.12Ohm load.
Analog/TTL modulation (Analog is single ended)
LD-Output inhibit via user definable Temperature tolerance and settling time parameters.
GUIs:
Main, Presets, Error-management and Data-logging
Individual activation/deactivation of the TEC-Driver channels A/B
Individual activation/deactivation of the Fan-Driver channels A/B
Monitoring of Temperature, TEC current, heating/cooling, H-Bridge temperature flags, TEC current limiting, Laser diode current, Laser diode power via Laser Bee II (Jerry hope you don’t mind) and PWM duty cycle.
User adjustable parameters:
All parameters except LD-Current and bias (next version LD-current and bias will be controlled via digital pots) are set via the Main GUI. Temperature, TEC Current limit, Invert heating/cooling, PID gains and windup limiting, Temperatures for fan on/off (next version PWM controlled), temperature tolerance for LD-Inhibit, temperature settling time for LD-Inhibit.
All user adjustable parameters can be saved as presets to the integrated SQL database. No limit to the number of presets which can be saved.
Service mode for manual control of output settings.
Error-management with error-text output. Errors are stored to EEPROM memory until acknowledged and cleared. Monitored are things like open circuit and short circuit of the thermistors, calibration fail, Bridge temperature flags. Some errors will force shutdown like thermistor failure or exceeding of the user defined settling time.
Individually user selectable data logging of all variables. Logged data can be saved to the integrated SQL database with export to Excel possibility. Adjustable sample rate from 10/s up to 5/h. Data accumulation can be monitored real-time on the integrated dynamic chart or in the Excel chart if opened before log begin.
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Originally Posted by edison
