On a single monolithic chip, the REF200 combines three circuit building blocks: two 100-A current sources and a current mirror. Because the parts are dielectrically isolated, they are totally self-contained. The current sources can also be utilised as current sinks because they are two-terminal devices.
Burr-Brown’s REF200 provides in independent 8-pin DIL package two independent current sources, either of which can supply 100 NA and a 1:1 current. mirror. The pinout of the device is shown in Fig. 1. Note that there are no pins for connecting a supply voltage. The correct operation of the current. sources are, however, guaranteed when the potential across the source is not less than 2.5 V. The average drift with temperature is only 25 p. p.m. K–1. The output impedance is not less than 100 MQ. The operating voltage must not exceed 40 V. The two sources and the mirror make possible a number of configurations, some of which are shown in Fig. 2. That in Fig. 2a is a 50 µA current source whose output voltage may vary between 0 and the positive supply voltage minus 2.5 V. In Fig. 2b, all parts of the IC form a floating 300 current source. Finally, Fig. 2c shows a bi-directional 100 source.
- Features
• Completely floating: no power supply or ground connections
• High accuracy: 100 µA ±0.5%
• Low-temperature coefficient: ±25 ppm/°C
• Wide voltage compliance: 2.5 V to 40 V
• Includes current mirror
The REF200 combines three circuit building blocks on a single monolithic chip: two 100-µA current sources and a current mirror. The sections are dielectrically isolated, making them completely independent. Also, because the current sources are two-terminal devices, they can be used equally well as current sinks. The performance of each section is individually measured and laser-trimmed to achieve high accuracy at a low cost.
The sections can be pin-strapped for currents of 50 µA, 100 µA, 200 µA, 300 µA, or 400 µA. External circuitry can obtain virtually any current. The REF200 is available in plastic 8-pin mini-DIP and SOIC packages
Applications
- Sensor Excitation
- Biasing Circuitry
- Offsetting Current Loops
- Low Voltage References
- Charge-pump Circuitry
- Hybrid Microcircuits
