博通(Broadcom)公司的BCM3545是高度集成低功耗的 QAM到NTSC单片转换器,提供SCTE-40 QAM信号接收方案.全硅方案的BCM3545最大限度地降低了元件数量,使得更容易生产.所集成的ADC和DAC简化了系统设计和成本,能直接接口到其它系统的元件如串行闪存(SPI),调谐器(I2C),按键和红外(IR)解调器.本文介绍了BCM3545的主要特性和优势,方框图以及应用系统方框图.
BCM3545 QAM Digital Receiver
The BCM3545 is a highly integrated low-power solution combining the functionality of a complete QAM-to-NTSC converter on a single chip. It provides SCTE-40 QAM signal reception, with functionality targeted at DTA specification or similar converter boxes for analog cable switch-off. This all-silicon solution minimizes part count and provides ease of manufacturing. The comprehensive integration of ADCs and DACs simplifies system design and cost and has direct interfaces to all other system components, including serial Flash (SPI), tuner (I2C), push buttons, and an Infrared (IR) demodulator. The BCM3545 has all security components to meet the DTA conditional access requirements, including ISO 7816 SmartCard interface, DVB-CSA, DVS-042, DES-ECB-CTS descramblers, 3DES key management, and bootloader ROM. Each BCM3545 will be factory OTP-programmed with its unique private password. JTAG and Broadband Studio ports may be OTP-locked at the stage of product factory test. A high-fidelity fixed 54-MHz crystal clock is used to clock in the 12-bit ADC.
The BCM3545 has an MPEG-2 Digital Video Broadcasting (DVB)- compliant transport processor with advanced section filtering capability, MPEG-2 (MP@ML profile) video decoder, a Broadcast Television Systems Committee (BTSC) audio encoder, a Dolby AC3/MPEG-2 audio decoder, a pair of analog audio outputs (L-R), and a single NTSC video encoder with analog output. The BCM3545 incorporates a complete MIPS32®-based microprocessor subsystem, including caches with bridging-to-memory and a local bus, where external peripherals can be attached. Integrated peripherals include a universal asynchronous receiver/transmitter (UART), counter/timers, general-purpose input/output (GPIO), Infrared (IR) transmit (TX)/receive (RX), Broadcom Serial Control (BSC), and Serial Peripheral Interface (SPI) controllers.
主要特性:
Complete digital-to-analog (DAC) converter System-on-a- Chip solution
SCTE-40-compliant when used with BCM3409 QAM tuner
Integrated receivers:
4–1024 QAM receiver
12-bit analog-to-digital converter (ADC) with internal AGC
All-digital clock and carrier recovery
Digital video and audio capability:
MP@ML MPEG-2 SD video decoder
Dolby® Digital (AC-3) and MPEG-2 Audio Decode
National Television Standards Committee (NTSC) SD Video Encoder
Integrated Analog Circuitry:
On-chip ADCs for IF signals
Simultaneous composite video broadcasting signal (CVBS) and S-Video output via triple video DACs
Dual-channel audio DACs for L-R audio
Dual linear voltage regulator controllers
High-quality graphics and video scaling capability
Support for EAS emergency broadcast, CEA708/608 Closed Captioning, and Parental Control (V-chip)
Channel 3/4 modulator with integrated BTSC encoder
On-chip 250-MHz 32-bit CPU
Extremely low power dissipation (<0.1W) in standby mode
Total DAC box system power less than 8W
340-PBGA optimized for two-layer PCB routing
主要优势:
Highly integrated solution combining the functionality of a complete QAM-to-NTSC converter on a single chip.
Integration of field proven QAM receivers.
Complete solution, including BCM3409 tuner, meets SCTE- 40 Receiver Performance Guidelines.
All-silicon solution minimizes parts count and provides ease of manufacturing.
Integrated security, including ISO 7816 SmartCard interface, DVB-CSA, DVS-042, DES-ECB-CTS descramblers, 3DES key management, JTAG lock, and secure bootloader ROM
Advanced graphics engine provides rich user interface environment.
Comprehensive integration of ADCs and DACs simplifies system design and cost.
Full peripheral support eliminates the need for additional components, including LED/Keypad, BSC/SPI master, IR receiver/blaster, PWM, and dual UARTs.
Broadcom-provided embedded software binary and PCB schematics for turnkey converter manufacturing.
图1. BCM3545方框图
图2. BCM3545系统方框图
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