Analog ICs that Complete the System

After integrating everything except the kitchen sink, the most complex microprocessors, microcontrollers, and digital signal processors rely on analog integrated circuits (ICs) to perform those functions that would be either prohibitively expensive or impossible to integrate in the digital portion. Analog IC makers continue to design these system—completing circuits with higher levels of integration and more features into more efficient, heat-dissipating packages. Examples of I/O expander, back light controller, power switching, and LED driver demonstrate the type of circuits built using analog IC technology.

WHITE LED DRIVER IC

Vishay Intertechnology Inc. (VSH) developed two white LED drivers that deliver up to 80 percent efficiency for compact handheld and battery-operated electronics such as digital cameras and cell phones. The SiP12401 and SiP12501 boost controllers provide controlled brightness for series connected LEDs using a double-cell NiMH or Alkaline and Lithium ion battery without the need for ballast resistors and operate over an input voltage range of 1.8 to 5.0V. Both units use a voltage-mode PWM design with internal frequency compensation to reduce system components and weight. The two LED drivers are available in a lead-free, 6-pin PowerPAK MLP33 package and are rated for operation over the industrial temperature range of 40 to 85C. For more information on Vishay LED driver ICs, go tohttp://rbi.ims.ca/ 4416-509.

I/O EXPANDERS

Microchip Technology developed two 16-bit I/O expanders, the MCP23X17 and MCP23S17, which increases port availability on a microcontroller. The expanders use existing serial ports—reducing cost and saving development time by eliminating a complete system design with a higher I/O microcontroller. The 16-bit I/O expander supports standard (100 kHz), fast (400 kHz) and high-speed (up to 1.7 MHz) I2C communications. For higher throughput applications, the MCP23S17 features SPI clock speeds up to 10 MHz. Both the MCP23017 and MCP23S17 have a standby mode that draws less than 2 µA and can operate down to 1.8V. Lead-free packaging includes 28-pin PDIP, SOIC, SSOP, and 6x6-mm QFN options. For more information on Microchip's 16-bit I/O expanders, go tohttp://rbi.ims.ca/4416-506.

FULL-BRIDGE LCD BACKLIGHT CONTROLLER

Fairchild Semiconductor's FAN7310 series parallel resonant converter provides high efficiency single stage power conversion for backlighting control. With a pulse width modulation (PWM) controller to develop a supply voltage, units can operate between 30 kHz and 250 kHz based on transformer's and Cold Cathode Fluorescent Lamp (CCFL) characteristics. The FAN7310 has synchronizable switching frequency with an external signal, soft start function, and a zero voltage switching full-bridge topology. Units incorporate a precision voltage reference trimmed to 2 percent, provide back light lamp ballast and soft dimming functions, and operate over an input voltage range from 5 to 24V. The FAN7310 offers both analog and burst dimming functions as well as open lamp protection and regulation in a 20-pin SSOP package. For more information on Fairchild's FAN7310, go to http://rbi.ims.ca/4416-507.

FOUR-CHANNEL, HIGH-SIDE POWER IC

Infineon has developed a new multi-channel high-side series of SMART5 PROFET switch ICs. Designed for automotive body and comfort applications, the power ICs provide an alternative to relay, fuse and discrete components. The BTS 5441G is a four-channel high-side SMART5 PROFET with several protection and diagnostic functions. Built-in protection includes ReverSave where channels switch on when reverse polarity is applied, reverse battery protection, over-load protection, short circuit protection, multi-step current limit, thermal shutdown with restart, and thermal restart at reduced current limits. Using four 25 mO N-channel vertical power MOSFETs with charge pump, the self-diagnosing chips can be driven directly by a microcontroller offering greater flexibility and lower cost. The SMART5 intelligent switches are ideal for automotive lighting applications such as daylight running lamps. For more information on Infineon's high current PROFETs, go tohttp://rbi.ims.ca/4416-508.