Analog Devices Inc./Maxim Integrated

The MAX753/MAX754 drive cold-cathode fluorescent lamps (CCFLs) and provide the LCD backplane bias (contrast) power for color or monochrome LCD panels. These ICs are designed specifically for backlit notebook-computer applications.Both the backplane bias and the CCFL supply can be shut down independently. When both sections are shut down, supply current drops to 25µA. The LCD contrast and CCFL brightness can be adjusted by clocking separate digital inputs or using external potentiometers. LCD contrast and backlight brightness settings are preserved in their respective counters while in shutdown. On power-up, the LCD contrast counter and CCFL brightness counter are set to one-half scale.The ICs are powered from a regulated 5V supply. The magnetics are connected directly to the battery, for maximum power efficiency.The CCFL driver uses a Royer-type resonant architecture. It can provide from 100mW to 6W of power to one or two tubes. The MAX753 provides a negative LCD bias voltage; the MAX754 provides a positive LCD bias voltage.ApplicationsNotebook ComputersPalmtop ComputersPDAs and Other Handheld DevicesPen-Based Data SystemsPortable Data-Collection Terminals

The MAX750A/MAX758A are adjustable-output, CMOS, step-down, DC-DC switching regulators. The MAX758A accepts inputs from 4V to 16V and delivers 750mA, while the MAX750A accepts inputs from 4V to 11V and delivers 450mA. Typical efficiencies are 85% to 90%. Typical quiescent current is 1.7mA, or only 6µA in shutdown mode. The output does not exhibit any ripple at subharmonics of the switching frequency over its specified range.Pulse-width-modulation (PWM) current-mode control provides precise output regulation and excellent transient responses. Output voltage accuracy is guaranteed to be ±4.5% plus feedback-resistor tolerance over line, load, and temperature variations. Fixed-frequency switching and absence of subharmonic ripple allows easy filtering of output ripple and noise, as well as the use of small external components. These regulators require only a single inductor value to work in most applications, so no inductor design is necessary.ApplicationsCell PhonesComputer PeripheralsPortable Communications EquipmentPortable Instrumentation

The MAX750A/MAX758A are adjustable-output, CMOS, step-down, DC-DC switching regulators. The MAX758A accepts inputs from 4V to 16V and delivers 750mA, while the MAX750A accepts inputs from 4V to 11V and delivers 450mA. Typical efficiencies are 85% to 90%. Typical quiescent current is 1.7mA, or only 6µA in shutdown mode. The output does not exhibit any ripple at subharmonics of the switching frequency over its specified range.Pulse-width-modulation (PWM) current-mode control provides precise output regulation and excellent transient responses. Output voltage accuracy is guaranteed to be ±4.5% plus feedback-resistor tolerance over line, load, and temperature variations. Fixed-frequency switching and absence of subharmonic ripple allows easy filtering of output ripple and noise, as well as the use of small external components. These regulators require only a single inductor value to work in most applications, so no inductor design is necessary.ApplicationsCell PhonesComputer PeripheralsPortable Communications EquipmentPortable Instrumentation

-12V, Inverting, PWM, Current-Mode DC-DC Converter