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Large analog systems that impose many loads on the reference voltage often demand more current than a single voltage-reference IC can deliver. A common solution is to add a buffer circuit at the reference-IC output, but reference accuracy is then degraded by the buffer's offset voltage. This article presents an alternative approach to the problem.

A better solution is to put the buffer inside the feedback loop of the reference error amplifier. The buffer then has no effect on reference accuracy. That configuration is, however, possible only for reference ICs in which the loop is accessible to users. The MAX6033A voltage reference in Figure 1 provides output force and sense pins for that purpose. The device also features a SOT23 package, 0.04% initial accuracy, and a 7ppm/°C temperature coefficient.


Figure 1. Adding a transistor buffer in the error-amplifier feedback loop of this voltage-reference IC boosts the output-current capability (to 80mA, in this case) without degrading the IC's output accuracy.