Nearly all of the current and future released handheld devices are required to charge from USB sources and AC wall adapters. This presents several challenges for battery charging. In this article we will discuss features that simplify USB charging: Which features assist the user in designing a USB-compliant application? How does the design support both USB and AC adapter inputs?

This article will discuss quiescent currents, input-voltage dynamic power management (VIN-DPM), and input-current limits, and the impact of the Chinese charger specification. The bq2407x series of ICs is used as examples to show these features. It is presented in two parts in pdf format (no registration required):

• Part 1 covers input-current limits and USB startup concerns, click here.
• Part 2 covers weak-battery threshold, input-voltage-based dynamic power management, and the Chinese charger standard, click here.

About the Author
Will Hadden is a Systems Engineer at Texas Instruments for the Battery Charge Management Group within Power Management. He has many years of experience with battery charger and analog power supply integrated circuits, and can be reached at ti_willhadden@list.ti.com.