High-Efficiency, Low-Output-Ripple Power Supply Reference Design for Imaging Applications
The point-of-load power-tree for video surveillance systems can be optimized with the TIDA-01579 reference design from Texas Instruments. This reference design delivers high performance on key parameters such as output voltage accuracy, voltage ripple, and thermal dissipation. This performance is delivered with a small board area and low BOM cost.
The design operates from a 5-V supply commonly found in video doorbells, IP network cameras, and wireless cameras.
Video surveillance products such as a video doorbell or Wi-Fi® camera typically consist of a power processor interfacing with high-speed image sensor and video encoder. The processor also interfaces with SD ram, audio codec supporting two-way audio communication, lens driver with IR cut filter sub circuitry.
From a power perspective, many different supply rails need to be generated to drive core voltage, I/O rail, and for the previously-mentioned peripherals.
Summary of features:
- 1% Typical output voltage accuracy
- High system efficiency to 90% at full load
- Voltage ripple < 60-µV, useful for noise-critical peripherals
- Thermal hot spot is < 45°C at full load current
- Small PCB real estate
- Low BOM cost
TIDA-01579 reference design block diagram.
Video doorbells provide a set of features common to many traditional video surveillance devices. This distinguishing feature demands a unique power design to ensure trouble-free operation from the ubiquitous, but widely-varying, ac doorbell supply. To fully utilize an ac source that presents a substantial bottleneck, the power design should be as efficient as possible. This design uses TI's new synchronous buck converters and LDOs providing a complete and customizable supply optimized for video doorbells.
TI's newest converters in QFN and SOT-563 packages allow for a supply design that requires minimal board space and has a low thermal impact—both of which are needed for smaller form factor electronics. For better compatibility, sequencing is possible for all rails.
IP network cameras have increasing image resolution, processing, and illumination requirements while still fitting in small enclosures. After stepping down from a mid- to high-voltage dc power source such as plugin power or PoE, the system demands point-of-load conversion with high efficiency and a small footprint. Both efficiency and footprint are important to accommodate small enclosures with, typically, less-than adequate ventilation.
This design is optimized for both efficiency and footprint while also providing the flexibility to tailor to more advanced, power-demanding loads, such as a dedicated image recognition processor or 4K video processor.
Wireless or battery-powered cameras require high efficiency at both full loads and light loads. These cameras typically employ motion detection, human interface, or wireless communications monitoring, or any combination of the three, to minimize time spent in power-hungry states quiescent currents and shutdown currents of subsystems are very important as these standby currents can have significant impact on overall battery life.
The TIDA-01579 reference design has been optimized for this application by utilizing TI's low-power converters featuring both light load efficiency and shutdown with low Iq. Converter shutdown and low-Iq load switches can be used to cut power to subsystems with less-than-desirable standby consumption—saving cost and extending battery life.
