DESCRIPTION

The WM8351 is an integrated audio and power management subsystem which provides a cost effective, single-chip solution for portable audio and multimedia systems.

The integrated audio CODEC provides all the necessary functions for high-quality stereo recording and playback. Programmable on-chip amplifiers allow for the direct connection of headphones and microphones with a minimum of external components. A programmable low-noise bias voltage is available to feed one or more electret microphones. Additional audio features include programmable high-pass filter in the ADC input path.

The WM8351 includes four programmable DC-DC converters, four low-dropout (LDO) regulators and a current limit switch to generate suitable supply voltages for each part of the system, including the integrated audio CODEC as well as off-chip components such as a digital core and I/O supplies, and LED lighting. An additional on-chip regulator maintains the backup power for always-on functions. The WM8351 can be powered by a lithium battery, by a wall adaptor or USB.

An on-chip battery charger supports both trickle charging and fast (constant current, constant voltage) charging of single-cell lithium batteries. The charge current, termination voltage, and charger time-out are programmable to suit different types of batteries.

Internal power management circuitry controls the start-up and shutdown sequencing of clocks and supply voltages. It also detects and handles conditions such as under-voltage, extreme temperatures, and deeply discharged or defective batteries, with a minimum of software involvement.
A programmable constant-current sink is available for driving LED strings, e.g. for display backlights or photo-flash applications, in a highly power-efficient way. Additional RGB LEDs can be driven through GPIO pins.

The WM8351 includes a 32.768kHz crystal oscillator, an internal RC oscillator, a real time clock (RTC) and an alarm function capable of waking up the system. Internal circuitry can generate all clock signals required to start up the device. The master clock for the audio CODEC can be input directly, or may be generated internally using an integrated, low power Frequency Locked Loop (FLL).

To extend battery life, fine-grained power management enables each function in the WM8351 to be independently powered down through the control interface. The WM8351 forms part of the Wolfson AudioPlus^TM series of audio and power management solutions.