SBVS020C September 2000 – February 2020 REF200
Applications for the REF200 are limitless. Application Bulletin AB-165 (SBOA046) shows additional REF200 circuits as well as other related current source techniques. In this section, a collection of circuits are shown to illustrate some techniques.
If the current sources are subjected to reverse voltage, a protection diode may be required. A reverse voltage circuit model of the REF200 is shown in Figure 6. If reverse voltage is limited to less than 6 V or reverse current is limited to less than 350 µA, then no protection circuitry is required. A parallel diode (see (a) in Figure 17) protects the device by limiting the reverse voltage across the current source to approximately 0.7 V. In some applications, a series diode may be preferable (see (b) in Figure 17), because it allows no reverse current. This configuration, however, reduces the compliance voltage range by one diode drop.