Video and digital camera applications have a variety of power management challenges created by the lack of standardization of battery sources. Both single cell Li-Ion/Polymer and two series connected NiMH are in use today, which creates the need for LCD display LED backlighting, LCD biasing and RGB indicator lamps, in addition to high efficiency step-up and step-down converters. Due to the differing charging characteristics of the two battery types, input port protection is especially critical to avoid catastrophic failures.
Buck and Boost Converters
Video and digital cameras need high efficiency power conversion to create regulated voltage rails from their battery source supply to maximize operating times between charge cycles.
Point of load voltage regulators provide a local supply rail with high efficiency
Single output high efficiency DC/DC switching regulators can provide either a step-up or step-down voltage output.
Video and digital cameras utilize color LCD displays for the image viewfinder as well as displaying camera functions and controls. Color LCD displays use white LED backlighting that require backlight power management solutions to provide high power conversion efficiency with flexible dimming control to maximize battery life between charge cycles.
LEDs are normally connected in series and therefore require a compliance voltage significantly higher than the battery voltage.
Panel size and resolution determine the number of white LEDs (WLED) required to produce the necessary screen brightness
Dimming techniques to control the brightness can range from simple linear LED brightness control to sophisticated high efficiency PWM control to achieve contrast ratios of typically 20,000:1
High accuracy current sinks to provide uniform backlight across larger panel sizes
High efficiency boost power conversion required to minimize demands on battery power consumption and maximize the battery life between charge cycles
Multiple series/parallel strings of WLED drivers to match the display panel needs
Multiple programming options from simple PWM signal control to full-featured I2C interfaces.
Advanced design, low drop-out current sinks with tight linearity characteristics to maintain constant LED current accuracy over all battery voltage extremes
High efficiency boost converters with integrated protection against LED open and short-circuit conditions
2-Channel LCD Panel Bias Supply with Single Inductor
Overvoltage and Surge Protection ICs
Input power port protection is a paramount concern in video and digital still camera design, as multiple power sources may be used.
Over-voltage, and surge protected load switches protect battery charge management and operating handset circuits, by breaking the connection between the power source and the internal circuitry, in the event the device is connected to a faulty power source or subjected to an abnormal stress condition.
Programmable and fixed over-voltage protection (OVP) shutdown thresholds.
Wrong adapter up to +40V
Reverse voltage down to -6V
Transient voltage protection up to 200V, compliant to IEC61000-4-2 (Level 4)
ESD protection compliant to ±8kV contact, ±15kV air gap and ±2kV human body model.
Single or dual devices with Uni or Bi-directional blocking
Integrated load switches provide internal power switching and are controlled by simple GPIO logic.
Eliminate the need for bias and level shift circuits associated with discrete MOSFET switches
Provides slew-rate limited turn-on with reverse current blocking and output discharge mode to de-select functions when not required to extend battery life.