Circuit function
Battery-powered electronic circuits must use low power. For the amplifier circuit, it is only necessary to use a low power OP amplifier. However, it is cumbersome to achieve low power consumption of the reference voltage source. If the normal Zener diode reduces the bias current, the performance will deteriorate, so there should be a few MA operating current.
This circuit is a low-power reference voltage circuit using a low-power reference IC (LM385) that can be biased by 30 UA.
Circuit working principle
There is nothing special about the circuit configuration. It is the same as the circuit of "temperature-compensated Zener diode + 10V reference voltage generation circuit", but a low-power OP amplifier is selected, and the confidence resistor uses a high resistance value to minimize the current consumption.
If the bias current IS of the reference diode is 30 UA, R1 = (VO - VZ) / IZ = 83K, R2 is determined by the current IS flowing through the resistor divider circuit. If IB is small, 1 UA, then R2 = (VO- VZ) / IB = 25K. R3+VR1 depends on VZ/IB. If the variation range is ±5%, then R3≤(VS/IB)*0.95=237K, VR1≥(VX/IB)*0.1=25K. The resistance of 220K, 50K is relatively easy to obtain, so the resistance value is chosen.
The power consumed by the OP amplifier accounts for a large proportion, the TL060's IOO=150UA, the TLC27L7's 10UA, and some low-power OP amplifiers. Can be selected according to the use requirements.
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