Today's portable and wearable devices basically have recording and audio playback capabilities, which greatly enhances the consumer experience. However, as functionality continues to increase, consumers are demanding that these devices be lighter, thinner, shorter, smaller, and provide longer battery life. This trend is facing more stringent design challenges for electronic component engineers: Achieve high quality, advanced digital signal processing (DSP) algorithms that save space and power. To this end, ON Semiconductor introduced the LC823450 ultra-low-power single-chip solution that provides high-resolution sound processing and integrates the functions required for audio applications while reducing costs.
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Overview of LC823450
The LC823450 is an audio processing system LSI that powers the energy-efficient ARM® Cortex®-M3 core and 32-bit/192 kHz audio processing engine supporting hardware-based MP3 encoding/decoding and wireless audio. Improve performance and power efficiency. With its abundant on-chip SRAM (1656 kbytes), the LC823450 provides a large amount of memory for audio processing and application tasks without the need for an auxiliary memory chip. Designers can also take advantage of a rich set of integrated audio peripherals such as analog/digital converters, phase-locked loops, and class D amplifiers. In addition, industry standard interfaces such as SPI, I2C, SDCard, and UART enable product designers to have built-in universal connections.
Figure 1: Low Power, High Resolution Audio Processing System LSI - LC823450
Advantages of the LC823450
Ultra low power consumption
The LC823450 uses ultra-low power technology, which is widely used in tape recorders (voice, music recording), mobile music phones and portable memory players to provide the longest battery life on the market. After benchmarking, the LC823450 has 70% more playback time than competing devices.
2. Small size
The LC823450 has integrated analog functionality, which reduces PCB space. Especially when using the WLCSP package, the package size is only 5.52mm x 5.33mm, which is about 50% smaller than the competitor's similar devices, which is in line with the trend of slimmer wearable applications.
3. Software modules and DSP algorithms
To accelerate software design and minimize development costs, ON Semiconductor offers a one-stop software service that includes a large library of digital signal processing (DSP) code libraries that are free of royalty and license-free fees, and development services based on customer requirements. Includes advanced features such as noise cancellers, and low frequency intelligent virtual excitation (S-Live) for enhanced low frequency playback. In mobile devices, a small speaker is often used to reduce the size and weight of the device. However, small speakers cannot play low frequencies and the sound quality will drop. S-Live uses ON Semiconductor's patented psychoacoustic bass enhancement algorithm to virtually play bass signals. Noise cancellers are available for non-stationary noise cancellation in audio applications.
Characteristics of LC823450
Figure 2: Block diagram of LC823450
1. Cortex-M3 dual core, AMBA® (AHB/APB) system
· Internal SRAM (1.5Mbytes)
· Internal ROM (256 bytes)
· SDRAM controller
64M to 256M bit SDRAM / mobile SDRAM
· External memory controller
Support NOR Flash, SRAM, ROM, and 8/16-bit LCD controller interface
Internal ROM boot and external storage boot available
· DMA controller (8ch)
· Interrupt controller (external 90ch, internal 82ch)
· Serial Peripheral Interface SPI (1ch)
· Serial Flash interface (1ch)
Four-wire serial peripheral interface, cache memory (16kbytes, 4-way set associative, 128-line) function
1.8 V dedicated power supply
· UART (3ch)
UART1: Flow Control (Clear Send, Request Send)
UART0, UART2: Flow Control
· I2C (2ch) single host
· GPIO (90ch)
· Plain Timer / Watchdog Timer (1ch x 3)
· Multiple timers (2ch x 4)
· 10-bit ADC (6ch)
· SD card interface (3ch)
SD0: Support eSD/eMMC boot (built-in ROM Boot function), 1.8 V dedicated power supply
SD1: Multi-channel memory module interface, 1.8 V dedicated power supply
SD2: 1.8 V dedicated power supply
· USB2.0 host (high speed / full speed / low speed) controller, device (high speed / full speed) controller. USB function requires integrated physical layer Xtal (XT1)
48 MHz for the host, 12/20/24/48 MHz for the device OTG function, the host and device share the integrated physical layer
· Real Time Clock (RTC)
Available in both universal RTC and KeyInt RTC modes, KeyInt RTC enables power-up
· Support Serial Wire Debug (SWD) as a debug interface
Supports Serial Line Viewer (SWV) as a tracking interface that tracks only one Cortex-M3 core
2. Hardware-based MP3 encoder/decoder : MP3 MPEG1, MPEG2, MPEG2.5
3. LPDSP32 system
· Internal SRAM (120k bytes)
· Internal ROM (220k bytes)
· WMA (Microsoft WMA Decoder Profile)
· AAC (MPEG4 LC-AAC)
· Variable speed control playback (0.5 to 4 times speed)
Up to 2x speed when playing with WMA and AAC
Up to 4 times faster when playing in PCM
Up to 4x speed when playing with hardware-based MP3
· Noise canceller
4. Can provide Bluetooth protocol stack
5. Other audio functions
· 6-band equalizer (EQ3)
· Volume, mute
· Noise meter
· Audio Timer / Interrupt Generator
· 16/24/32 bit 192 kHz PCM interface (2ch x 2)
· Synchronous Sampling Frequency Converter (SSRC)
· Asynchronous Sampling Frequency Converter (ASRC): Reduce jitter to support USB audio and Bluetooth streaming
· Beep generator
· Digital microphone interface (2ch x 1)
· 16-bit audio DAC (2ch)
Class D amplifiers are used for headphones (2ch). Requires an external LC low pass filter
6. Audio clock generator
· Dedicated phase-locked loop for audio
· Optional phase-locked loop reference clock
to sum up
With its advanced integration and high power efficiency, ON Semiconductor's advanced audio processing single-chip solution, the LC823450, provides a superior experience for mobile devices such as portable and wearables, and high-resolution audio takes hearing enjoyment to the next level. Rich integration features, hardware acceleration and simple software terms simplify product designers, reduce development costs, and speed time to market.
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