Analog Devices Inc./Maxim Integrated

The LT3472 dual channel switching regulator generates positive and negative outputs for biasing CCD imagers. The device delivers up to –8V at 50mA and 15V at 20mA from a lithium-ion cell, providing bias for many popular CCD imagers. Switching at 1.1MHz, the LT3472 uses tiny, low profile capacitors and inductors and generates low noise outputs that are easy to filter. Schottky diodes are internal and the output voltages are set with one resistor per channel, reducing external component count. The entire solution is less than 1mm profile and occupies just 50mm2.Internal sequencing circuitry disables the negative channel until the positive channel has reached 88% of its final value, ensuring that the sum of the two outputs is always positive. Separate soft-start capacitors for each output allow the ramp of each output to be independently controlled.The LT3472 is available in a low profile (0.75mm) 10-pin 3mm × 3mm DFN package.ApplicationsCCD BiasTFT LCD BiasOLED Bias± Rail Generation for Op Amps

The LT3473/LT3473A are micropower step-up DC/DC converters with integrated Schottky diode and output disconnect circuitry in low profile DFN packages. The small package size, high level of integration and the use of tiny SMT components yield a solution size of less than 50mm2. The internal 1A switch allows the device to deliver 25V at up to 80mA from a Li-Ion cell, while automatic Burst Mode operation maintains efficiency at light load. An auxiliary reference input (CTRL) allows the user to override the internal 1.25V feedback reference with any lower value, allowing full control of the output voltage during operation. APGOODpin sinks current when the output voltage reaches 90% of final value.The LT3473A includes two NPN transistors for generating intermediate bias voltages from the output and is offered in a 12-lead (4mm × 3mm) DFN package. The LT3473 does not include these NPNs and is offered in an 8-lead (3mm × 3mm) package.The rugged 36V switch and output disconnect circuitry allow outputs up to 34V to be easily generated in a simple boost topology.ApplicationsOLED BiasCCD Bias

The LT3477 is a current mode, 3A DC/DC step-up converter with dual rail-to-rail current sense amplifiers and an internal 3A, 42V switch. It combines a traditional voltage feedback loop and two unique current feedback loops to operate as a constant-current, constant-voltage source. Both current sense voltages are set at 100mV and can be adjusted independently using the IADJ1and IADJ2pins. Efficiency of up to 93% can be achieved in typical applications. The LT3477 features a programmable soft-start function to limit inductor current during start-up. Both inputs of the error amplifier are available externally allowing positive and negative output voltages (boost, inverting, SEPIC, Flyback). The switching frequency is programmable from 200kHz to 3.5MHz through an external resistor.Available in thermally enhanced 20-pin (4mm × 4mm) QFN and 20-pin TSSOP packages, the LT3477 provides a complete solution for both constant-voltage and constantcurrent applications.ApplicationsHigh Power LED DriverDSL ModemsDistributed PowerInput/Output Current Limited Boost, SEPIC, Inverting, Flyback ConvertersConstant-Voltage, Constant-Current Source

The LT3478/LT3478-1 are 4.5A step-up DC/DC converters designed to drive LEDs with a constant current over a wide programmable range. Series connection of the LEDs provides identical LED currents for uniform brightness without the need for ballast resistors and expensive factory calibration.The LT3478-1 reduces external component count and cost by integrating the LED current sense resistor. The LT3478 uses an external sense resistor to extend the maximum programmable LED current beyond 1A and also to achieve greater accuracy when programming low LED currents. Operating frequency can be set with an external resistor from 200kHz up to 2.25MHz. Unique circuitry allows a PWM dimming range up to 3000:1 while maintaining constant LED color. The LT3478/LT3478-1 are ideal for high power LED driver applications such as automotive TFT LCD backlights, courtesy lighting and heads-up displays. One of two CTRL pins can be used to program maximum LED current. The other CTRL pin can be used to program a reduction in maximum LED current vs temperature to maximize LED usage and improve reliability.Additional features include inrush current protection, programmable open LED protection and programmable soft-start. Each part is available in a 16-pin thermally enhanced TSSOP Package.ApplicationsHigh Power LED DriverAutomotive Lighting