Wolfson WM8351单片多媒体系统解决方案

Wolfson公司的 WM8351是手提音频和多媒体系统单片解决方案. WM8351集成了包括有四个可编程DC/DC转换器,四个LDO稳压器和限流开关的音频和电源管理系统以及音频CODEC系统. WM8351的系统控制支持2线或3/4线控制接口.它还集成了LED驱动器和电池充电器.其它特性还包括”常开”的带叫醒告警的RTC,看门狗定时器,多达13个可配置的GPIO引脚,以及晶体振荡器和RC振荡器与支持宽范围输入时钟的低功耗FLL.本文介绍了WM8351的主要特性,方框图以及应用和评估板WM8351-6143-EB129-M-REV1的详细电路图,包括控制部分, CODEC部分, 稳压电源部分, PIC初始化部分电路图和评估板材料清单(BOM).

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 AudioPlusTM series of audio and power management solutions.
WM8351主要特性:
Stereo Hi-Fi CODEC
DAC SNR 98dB (‘A’ weighted @ 48kHz), THD –84dB
ADC SNR 95dB (‘A’ weighted @ 48kHz), THD –80dB
40mW on-chip headphone driver with ‘capless’ option
16Ω headphone load: THD -70dB, 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  
1 x DC-DC Buck Converter (0.85V - 3.4V, Up to 1A)
2 x DC-DC Buck Converters (0.85V - 3.4V, Up to 500mA)
1 x DC-DC Boost Converter (5V - 20V, 40 to 200mA)
4 x LDO voltage regulators (0.9V - 3.3V, 150mA)
LED Drivers  
Programmable constant-current sink, 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





图1.WM8351方框图



图2.WM8351典型应用

WM8351-6143-EB129-M-REV1评估板



图3.WM8351评估板电路图(控制部分)



图4.WM8351评估板电路图(CODEC部分)



图5.WM8351评估板电路图(稳压电源部分)



图6.WM8351评估板电路图(PIC初始化部分)



图7.WM8351评估板电路图(连接器部分)



图8.WM8351评估板电路图(测试点部分)

WM8351评估板材料清单(BOM):