Wolfson WM8352 AudioPlus立体声CODEC方案

Wolfson公司的WM8352是有功率管理的AudioPlus立体声CODEC子系统,集成了高质立体声录音和播放所需的所有功能,可编程的片上放大器可直接连接到耳机放大器和麦克风.片中DAC的SNR为95dB,THD为-81dB,ADC的SNR为95dB,THD为-83dB,能向16欧姆的耳机提供THD=-72dB的输出功率20mW,主要应用在手提音频和媒体播放器,手提导航设备和其它手提系统.本文介绍了WM8352主要特性,方框图,系统方框图以及典型应用电路.

WM8352: Wolfson AudioPlus™ Stereo CODEC with Power Management

The WM8352 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 WM8352 includes six 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 WM8352 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.

Two programmable constant-current sinks are 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 WM8352 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 WM8352 to be independently powered down through the control interface. The WM8352 forms part of the Wolfson AudioPlusTM series of audio and power management solutions.

WM8352主要特性:

Stereo Hi-Fi CODEC

DAC SNR 95dB (‘A’ weighted @ 48kHz), THD –81dB

ADC SNR 95dB (‘A’ weighted @ 48kHz), THD –83dB

40mW on-chip headphone driver with ‘capless’ option

16Ω headphone load: THD -72dB, Po = 20mW

2 differential microphone inputs with low-noise bias voltage and programmable preamps

Programmable high-pass filter for ADC

Microphone and Headphone detection

Auxiliary inputs for analogue signals

Sample rates: 8, 11.025, 16, 22.05, 24, 32, 44.1 or 48kHz

System Control

Support for 2-wire or 3-/4-wire Control Interface

Handles power sequencing, reset signals and fault conditions

Autonomous power source selection (battery, wall adaptor or USB bus)

Total current drawn from USB bus is limited to comply with USB 2.0 standard and USB OTG supplement

Supply Generation

2 x DC-DC Buck Converters (0.85V - 3.4V, Up to 1A)

2 x DC-DC Buck Converters (0.85V - 3.4V, Up to 500mA)

2 x DC-DC Boost Converters (5V - 20V, 40 to 200mA)

4 x LDO voltage regulators (0.9V - 3.3V, 150mA)

LED Drivers

2 programmable constant-current sinks, suitable for screen backlight or white LED photo flash

3 open-drain outputs for RGB LEDs

Battery Charger

Single-cell Li-Ion / Li-Pol battery charger

Thermal protection for charge control; temperature monitoring available for thermal regulation

LED outputs to indicate charge status and fault conditions

Additional Features

“Always on” RTC with wake-up alarm

Watchdog timer

Up to 13 configurable GPIO pins

On-chip crystal oscillator and internal RC oscillator

Low power FLL supporting wide range of input clocks

7x7mm, 129 BGA package, 0.5mm ball pitch

WM8352应用:

Portable Audio and Media players

Portable Navigation Devices

Portable systems powered by single-cell lithium batteries

图1.WM8352方框图


图2.WM8352系统方框图(1)

图3.WM8352系统方框图(2)

图5.WM8352典型应用连接图