Linear Technology

LT3724: High Input Voltage DC/DC Controller for Step-Down, Step-Up, Inverting &

Mon, 13 Oct 2008 00:00:00 -0700

The LT3724 is a DC/DC controller used for medium power, low part count, low cost, high efficiency supplies. It offers a wide 4V-60V input range (7.5V minimum startup voltage) and can implement step-down, step-up, inverting and SEPIC topologies.The LT3724 includes Burst Mode operation, which reduces quiescent current below 100µA and maintains high efficiency at light loads. An internal high voltage bias regulator allows for simple biasing and can be back driven to increase efficiency.Additional features include fixed frequency current mode control for fast line and load transient response; a gate driver capable of driving large N-channel MOSFETs; a precision undervoltage lockout function; 10µA shutdown current; short-circuit protection; and a programmable soft-start function that directly controls output voltage slew rates at startup which limits inrush current, minimizes overshoot and facilitates supply sequencing.The LT3724 is available in a 16-lead thermally enhanced TSSOP package.

LT3513: 2MHz, Five Output Regulator for TFT-LCD Panels

Tue, 07 Oct 2008 00:00:00 -0700

The LT3513 5-output adjustable switching regulator provides power for large TFT-LCD panels. The 38-pin 5mm × 7mm QFN device can generate a 3.3V or 5V logic supply along with the triple output supply required for the TFT-LCD panel. A lower voltage secondary logic supply may also be generated with the addition of an external NPN driven by the internal linear regulator. A step-down regulator provides a low voltage output, VLOGIC, with up to 1.2A of current while capable of operating from a wide input range of 4.5V to 30V. A high power step-up converter, a lower power step-up converter and an inverting converter provide the three independent output voltages: AVDD, VON and VOFF required by the LCD panel. A high-side PNP provides delayed turn-on of the VON signal and can handle up to 30mA. Protection circuitry ensures that VON is disabled if any of the four outputs are more than 10% below the programmed voltage.

LT3085: Surface Mount 500mA LDO Is Easily Paralleled Without Hot Spots

Mon, 06 Oct 2008 00:00:00 -0700

The LT®3085 is a 500mA low dropout linear regulator that can be paralleled to increase output current or spread heat on surface mounted boards. Designed as a precision current source and voltage follower, this new regulator finds use in many applications requiring high current, adjustability to zero, and no heat sink. The device also brings out the collector of the pass transistor to allow low dropout operation—down to 275mV—when used with a second supply.A key feature of the LT3085 is the capability to supply a wide output voltage range. By using a reference current through a single resistor, the output voltage is programmed to any level between zero and 36V. The LT3085 is stable with 2.2μF of capacitance on the output, and the IC uses small ceramic capacitors that do not require additional ESR as is common with other regulators.Internal protection circuitry includes current limiting and thermal limiting. The LT3085 is offered in the 8-lead MSOP and a low profile (0.75mm) 6-lead 2mm × 3mm DFN package (both with an Exposed Pad for better thermal characteristics).

LT3972: 33VIN, 3.5A(IOUT), 2.4MHz Step-Down DC/DC Converter Draws Only

Thu, 02 Oct 2008 00:00:00 -0700

The LT®3972 is an adjustable frequency (200kHz to 2.4MHz) monolithic buck switching regulator that accepts input voltages up to 33V (62V Maximum). A high efficiency 95mΩ switch is included on the die along with a boost Schottky diode and the necessary oscillator, control, and logic circuitry. Current mode topology is used for fast transient response and good loop stability. Low ripple Burst Mode operation maintains high efficiency at low output currents while keeping output ripple below 15mV in a typical application. In addition, the LT3972 can further enhance low output current efficiency by drawing bias current from the output when VOUT is above 3V Shutdown reduces input supply current to less than 1μA while a resistor and capacitor on the RUN/SS pin provide a controlled output voltage ramp (soft-start). A power good flag signals when VOUT reaches 91% of the programmed output voltage. The LT3972 is available in 10-Pin MSOP and 3mm × 3mm DFN packages with exposed pads for low thermal resistance.

LT5581: 10MHz to 6GHz Low Power RMS Detector with 40dB Dynamic Range Provides

Wed, 01 Oct 2008 00:00:00 -0700

The LT5581 is a 10MHz to 6GHz, low power monolithic precision RMS power detector. The RMS detector uses a proprietary technique to accurately measure the RF power from –34dBm to +6dBm (at 2.14GHz) of modulated signals with a crest factor as high as 12dB. It outputs a DC voltage in linear scale proportional to an RF input signal power in dBm. The LT5581 is suitable for precision power measurement and control for a wide variety of RF standards, including GSM/EDGE, CDMA, CDMA2000, W-CDMA, TD-SCDMA, UMTS, LTE and WiMAX, etc. The ﬁnal DC output is connected in series with an on-chip 300Ω resistor, which enables further ﬁltering of the output modulation ripple with just a single off-chip capacitor.

LT3756: 100V, Full Featured LED Controller for Boost, Buck or

Wed, 24 Sep 2008 00:00:00 -0700

The LT3756 and LT3756-1 are DC/DC controllers designed to operate as a constant-current source for driving high current LEDs. They drive a low side external N-channel power MOSFET from an internal regulated 7V supply. The fixed frequency, current-mode architecture results in stable operation over a wide range of supply and output voltages. A ground referenced voltage FB pin serves as the input for several LED protection features, and also makes it possible for the converter to operate as a constant-voltage source. A frequency adjust pin allows the user to program the frequency from 100kHz to 1MHz to optimize efficiency, performance or external component size.The LT3756/LT3756-1 sense output current at the high side of the LED string. High side current sensing is the most flexible scheme for driving LEDs, allowing boost, buck mode or buck-boost mode configuration. The PWM input provides LED dimming ratios of up to 3000:1, and the CTRL input provides additional analog dimming capability. Both parts are available in the 16-lead QFN (3mm x 3mm) and MSOP packages.

LT3587: Dual Boost Plus Inverting DC/DC Converter for

Tue, 23 Sep 2008 00:00:00 -0700

The LT®3587 provides a one-chip solution for applications requiring two positive and one negative high voltage supplies.The LT3587 input voltage range of 2.5V to 6V makes it ideal for various battery-powered systems.A single resistor programs each of the three output voltage levels and the output current of Boost3. The intelligent softstart allows for sequential soft-start of the Boost1 output followed by the negative output with a single capacitor. Internal sequencing circuitry also disables the inverter until the Boost1 output has reached 87% of its final value.The LT3587 integrates all the power switches, soft-start, and output-disconnect circuits into a small 3mm x 3mm QFN package. This high level of integration combined with small external components makes the LT3587 ideal for space constrained applications.

LTC6802: High Voltage Battery Stack Monitor Supports

Mon, 22 Sep 2008 00:00:00 -0700

The LTC6802-1 is a complete battery monitoring IC that includes a 12-bit ADC, a precision voltage reference, a high voltage input multiplexer and a serial interface. Each LTC6802-1 can measure up to 12 series connected battery cells with an input common mode voltage up to 60V. Using a unique level-shifting serial interface, multiple LTC6802-1 devices can be connected in series, without optocouplers or isolators, allowing for monitoring of every cell in a long string of series-connected batteries.When multiple LTC6802-1 devices are connected in series they can operate simultaneously, permitting all cell voltages in the stack to be measured within 13ms.To minimize power, the LTC6802-1 offers a measure mode to monitor each cell for overvoltage and undervoltage conditions. A standby mode is also provided.Each cell input has an associated MOSFET switch for discharging overcharged cells.The related LTC6802-2 offers an individually addressable serial interface.

LTC3576: Switching Power Manager with USB On-The-Go & Overvoltage

Thu, 11 Sep 2008 00:00:00 -0700

The LTC®3576/LTC3576-1 are highly integrated power management and battery charger ICs for Li-Ion/Polymer battery applications. They each include a high efficiency, bidirectional switching PowerPath™ manager with automatic load prioritization, a battery charger, an ideal diode, a controller for an external high voltage switching regulator and three general purpose step-down switching regulators with I2C adjustable output voltages. The internal switching regulators automatically limit input current for USB compatibility and can also generate 5V at 500mA for USB on-the-go applications when powered from the battery. Both the USB and external switching regulator power paths feature Bat-Track optimized charging to provide maximum power to the application from supplies as high as 38V. An overvoltage circuit protects the LTC3576/LTC3576-1 from damage due to high voltage on the VBUS or WALL pins with just two external components. The LTC3576/LTC3576-1 are available in a low profile 38-pin (4mm × 6mm × 0.75mm) QFN package.

LTC3853: Triple Output Synchronous Step-Down DC/DC Controller

Wed, 10 Sep 2008 00:00:00 -0700

The LTC®3853 is a high performance triple output stepdown switching regulator controller that drives all N-channel synchronous power MOSFET stages. Power loss and supply noise are minimized by operating the output stages out of phase. The part can be configured as a dual phase controller plus a single phase controller if needed. The part can also be configured to provide a single 3-phase output for even higher output currents.A wide 4.5V to 24V (28V maximum) input voltage supply range encompasses most battery chemistries and intermediate bus voltages. Phase 3 can regulate output voltages up to 13.5V. A constant frequency current mode architecture allows for a phase-lockable frequency up to 750kHz.Independent TK/SS pins for each output ramps the output voltages and can be configured for coincident or ratiometric tracking. Current foldback limits MOSFET heat dissipation during short-circuit conditions. The MODE/PLLIN pin selects among Burst Mode® operation, pulse-skipping or continuous inductor current modes.