How to read datasheets
What is the main reason standby current is specified per temperature, such as "typ 0.5 µA at 25 °C, max 10 µA at 85 °C"?
- ABecause wiring resistance increases with temperature, causing correspondingly more current to flow
- BBecause transistor leakage current increases sharply as temperature rises
- CBecause the internal clock frequency automatically increases at high temperature
Show answer and explanation
Answer: B. Because transistor leakage current increases sharply as temperature rises
In standby the clock is stopped, and most of the current consumption is transistor subthreshold leakage and junction leakage. These increase exponentially with temperature, and it is not unusual for them to grow several to several tens of times from 25 °C to 85 °C. For battery-powered equipment, battery life must be estimated using the value at the upper end of the operating temperature range. Increased wiring resistance would, if anything, reduce current, so it is not the reason.