DC POWER SOURCE DETERMINATION CIRCUITRY FOR USE WITH AN ADAPTER

摘要

An adapter device includes a DC/DC adapter to receive DC power from a DC pow er source, and output a regulated DC voltage (V out). A source determination circuitry receives the DC power from the DC power source and compares a magnitude of a voltage of t he DC power with a reference magnitude of a reference voltage (V ref). When the magnitud e of the voltage of the DC power is greater than the reference magnitude, a data signal (V data) having a first value is output. When the magnitude of the voltage of the DC power is less than the reference magnitude, the V data signal having a second value is output. The V data signal is received by control circuitry of an electronic device. When the V data signal has the first value, the electronic device operates in a first mode where battery charging circuitry is disabled . When the V data signal has the second value, the battery charging circuitry is enabled.