What's the need for voltage detector ICs for batteries/supercapacitors?

In low-cost microcontrollers, like those used in most versions of the Arduino, there is no separate pin or internal circuit that supplies an analog reference voltage. Instead, the power supply voltage is used as a reference. So, the analog-to-digital converter always measures the input voltage as a fraction of the supply voltage.

Therefore, you can't measure the supply voltage directly. The supply voltage is always 100% of the supply voltage.

1 Votes

Elliot Alderson
August 13, 2019 19:29 PM

Reliability: When you need to detect a supply voltage drop and need to turn of e.g. all the machinery, then you don't want to rely on a microcontroller which might already be misbehaving because of undervoltage.

Also, especially the KA75XX are from a time where microcontrollers even lacked basic things like brownout detection and couldn't reset themselves. That's why they needed external circuitry to do that.

2 Votes

Marcus Müller
August 13, 2019 19:32 PM