User:Chotee/constantCurrentSink

Constant Current Sink

Goal: Will sink a constant current independent of the input voltage.

Range: 1mA to 5000mA. Max Vin 30V.

Ref 1 Build Notes

Adjustment

1. RV5 (reference voltage adjust) to 5V. Test point at P3.
2. Set SW_A1 to non-EXT value
3. RV1 (100mV voltage) to 100mV. Set SW2_B1 to bottom value, Set SW1_B1 to 1x gain (top pin). Use P1 as test point.
4. RV2 (10mV voltage) to 10mV. Set SW2_B1 next to bottom, Set SW1_B1 to 1x gain. Use P1 as test point.
5. RV3 (2x gain) to 100mV/10mV. Set SW1_B1 to 2x gain. Adjust until 200mV/20mV on P1

Errata

• R5 @ 1k8: wrong value. Cannot get 2x gain with 1k8+5k pot. Change to 6k8+5k pot to get 2x gain.
• R15 @ 10K: Doesn't give enough current to the LM336Z5.0. Switch to a lower resistance, 3k9 works for 9v input but. If 9v battery is used, voltage will droop till 7v during battery life. R15=1k5 will give stable reference 5V with a Vbat of 9V5 to 7V. Quiescent current does go up, but usable battery life will still be longer.

Links

• http://www.ti.com/lit/ds/symlink/lm136-5.0.pdf
• http://ww2.duracell.com/media/en-US/pdf/gtcl/Product_Data_Sheet/NA_DATASHEETS/MN1604_6LR61_US_CT.pdf