Power management system for active stylus

A stylus, comprising:

• one or more electrodes and one or more computer-readable non-transitory storage media embodying first logic for transmitting signals wirelessly to a device through a touch-sensor of the device;
• the stylus having:
• a first power mode in which components of the stylus for receiving signals from or transmitting signals to the device are powered off;
• a second power mode in which components of the stylus for receiving drive signals transmitted by drive electrodes of the device are periodically powered on and components of the stylus for transmitting signals to the device are powered off;
• and
• a third power mode in which components of the stylus for transmitting signals to the device are powered on at least periodically;
• wherein the media further embodies second logic for transitioning the stylus from one of the first, second, and third power modes to another one of the first, second, and third power modes, and for transitioning the stylus from the second mode to the third mode when the drive signals transmitted by the drive electrodes from the device are detected.