- on Miscellaneous Electronics
- Published in issue 12/2003 on page 0
Constant Current Sink
The precision current sink shown in Figure 1, which uses a Si4936 DY dual MOSFET (IC1) as a controlled load resistance, is very energy-efficient and thus particularly suitable for use in battery-powered equipment. The voltage drop across current-sense resistor R4 should be approximately 85 mV. IC2 and R4 form the actual current sink, which has a very low dropout voltage. The supply voltage can be reduced to as low as the operating voltage of the load. If the supply voltage is greater than this, transistor T1 in IC2 regulates the supply current.