Jon Titus
User Rank
Re: Part V: Tricks With PIC: Using the Trusty PIC Microcontroller
Jon Titus   1/20/2012 5:36:05 PM
Q: What would be your recommendation for measuring Battery voltage thru a micro A/D, say a 9-volt battery?  Simply using a voltage divider causes current draw while the micro is shut down.


A:  Yes, if you use two resistors to create a voltage divider you continue to draw current all the time.  Use a small NPN transistor between the resistors and ground and turn it on with an output pin at logic 0.  Then current will flow through the resistors and you can measure the voltage.  Just account for the voltage drop across the NPN transistor when you calculate the resistor values needed to get a voltage you can measure.

Partner Zone
Latest Analysis
Days after a massive, distributed denial-of-service attack took down dozens of major websites around the country, ARM Holdings plc is rolling out a pair of new processor architectures aimed at shoring up IoT security.
Dow Chemical and several other companies have launched a program in Omaha, Neb. to divert about 36 tons of plastics from landfills in its first phase, and convert it into energy used for cement production.
Both traditional automation companies and startups are developing technologies to improve processes on the factory floor, while smart sensors and other IoT-related technologies are improving how products are handled during transport and across the supply chain.
Remote monitoring now looks beyond the individual motor or conveyor and instead views the process from end to end.
BASF is partnering with Hyundai on a high-performance concept car that showcases both eco-friendly, sustainable materials and materials to enable lighter weight cars.
Quick Poll
The Continuing Education Center offers engineers an entirely new way to get the education they need to formulate next-generation solutions.
Oct 10 - 14, Embedded System Design Techniques™: Getting Started Developing Professional Embedded Software
SEMESTERS: 1  |  2  |  3  |  4  |  5  |  6 |  7 | 8 | 9 | 10

Focus on Fundamentals consists of 45-minute on-line classes that cover a host of technologies. You learn without leaving the comfort of your desk. All classes are taught by subject-matter experts and all are archived. So if you can't attend live, attend at your convenience.
Next Course September 27-29:
Sponsored by 3M
Learn More   |   Login   |   Archived Classes
Twitter Feed
Design News Twitter Feed
Like Us on Facebook

Technology Marketplace

Copyright © 2016 UBM Canon, A UBM company, All rights reserved. Privacy Policy | Terms of Service