Sunpower Inc. CryoTel
MT Operating Instructions version 4
18
XI. LED and 5 Pin Connector Summary
The two LED s, shown in figure 13, indicate whether the cooler has reached its set point
temperature or if the cooler is still in cool down mode. The red LED will be on as long as the
cooler is in cool down mode. When the cooler reaches its set point temperature within 0.5K the
green LED will turn on.
The 5-pin connector is connected to an optocoupler circuit as shown in Figure 15. When the
green LED is on, current is able to flow from pin 1 to pin 5 through the Darlington
Phototransistor. When the green LED is off, the current flow through the phototransistor is
blocked. This would be useful if the user wanted switch an externally powered indicator light
or control system input on when the cooler reaches the set point temperature. Pins 2, 3, and 4
on the 5 pin connector are not used.
Figure 14: Controller LED s and 5 pin Connector
Figure 15: Optocoupler Circuit.
Phototransistor is on when green LED is on.
PIN 1
PIN 5
Red LED
Green LED
5 pin connector
LED s
LED
PIN 1
PIN 5
Darlington
Phototransistor
(MOCD223)
