Linear Technology

LTC3412A: 4MHz, 3A Synchronous Step-Down Regulator Now Offered in High Reliability, MP-Grade Temperature Range

Thu, 02 Jul 2009 15:01:29 -0700

The LTC3412 is a high efficiency monolithic synchronous, step-down DC/DC converter utilizing a constant frequency, current mode architecture. It operates from an input voltage range of 2.625V to 5.5V and provides an adjustable regulated output voltage from 0.8V to 5V while delivering up to 2.5A of output current. The internal synchronous power switch with 85mOhm on-resistance increases efficiency and eliminates the need for an external Schottky diode. Switching frequency is set by an external resistor or can be sychronized to an external clock. 100% duty cycle provides low dropout operation extending battery life in portable systems. OPTI-LOOP® compensation allows the transient response to be optimized over a wide range of loads and output capacitors. The LTC3412 can be configured for either Burst Mode® operation or forced continuous operation. Forced continuous operation reduces noise and RF interference while Burst Mode operation provides high efficiency by reducing gate charge losses at light loads. In Burst Mode operation, external control of the burst clamp level allows the output voltage ripple to be adjusted according to the requirements of the application. To further maximize battery life, the P-channel MOSFET is turned on continuously in dropout (100% duty cycle).

LTC4269: High Power PD Controllers with Built-In Switchers Address IEEE 802.3at PoE+ Standard

Tue, 30 Jun 2009 16:13:14 -0700

The LTC4269-2 is an integrated Powered Device (PD) interface and power supply controller featuring 2-event classification signaling, flexible auxiliary power options, and a power supply controller suitable for synchronously rectified forward supplies. These features make the LTC4269-2 ideally suited for an IEEE802.3 at PD application. The PD controller features a 100V MOSFET that isolates the power supply during detection and classification, and provides 100mA inrush current limit. Also included are power good outputs, an undervoltage/overvoltage lockout and thermal protection. The current mode forward controller allows for synchronous rectification, resulting in an extremely high efficiency, green product. Soft-start for controlled output voltage start-up and fault recovery is included. Programmable frequency over 100kHz to 500kHz allows flexibility in efficiency vs size and low EMI.

LTC2656: 16-Bit Octal SPI DAC Achieves ±4LSB INL (Max)

Tue, 30 Jun 2009 08:30:49 -0700

The LTC2656 is a family of octal 16-/12-bit rail-to-rail DACs with a precision integrated reference. The DACs have built-in high performance, rail-to-rail, output buffers and are guaranteed monotonic.The LTC2656-L has a full-scale output of 2.5V with the integrated 10ppm/°C reference and operates from a single 2.7V to 5.5V supply. The LTC2656-H has a full-scale output of 4.096V with the integrated reference and operates from a 4.5V to 5.5V supply. Each DAC can also operate with an external reference, which sets the DAC full-scale output to two times the external reference voltage. These DACs communicate via a SPI/MICROWIRE™ compatible 4-wire serial interface which operates at clock rates up to 50MHz. The LTC2656 incorporates a power-on reset circuit that is controlled by the PORSEL pin. If PORSEL is tied to GND the DACs reset to zero-scale. If PORSEL is tied to VCC, the DACs reset to mid-scale.

LTC2463: 16-Bit I2C ADC Integrates 2ppm/°C Reference in 3mm x 3mm Package

Thu, 25 Jun 2009 09:18:03 -0700

The LTC2461/LTC2463 are ultra tiny, 16-Bit analog to digital converters with an integrated precision reference. They use a single 2.7V to 5.5V supply and communicate through an I2C Interface. The LTC2461 is single-ended with a 0V to 1.25V input range and the LTC2463 is differential with a 1.25V input range. Both ADCs include a 1.25V integrated reference with 2ppm/°C drift performance and 0.1% initial accuracy. The converters are available in a 12-pin 3mm × 3mm DFN package or an MSOP-12 package. They include an integrated oscillator and perform conversions with no latency for multiplexed applications. The LTC2461/LTC2463 include a proprietary input sampling scheme that reduces the average input current several orders of magnitude when compared to conventional delta sigma converters. Following a single conversion, the LTC2461/LTC2463 automatically power down the converter and can also be confi gured to power down the reference. When both the ADC and reference are powered down, the supply current is reduced to 200nA. The LTC2461/LTC2463 can sample at 60 conversions per second and, due to the very large oversampling ratio, have extremely relaxed antialiasing requirements. Both include continuous internal offset and fullscale calibration algorithms which are transparent to the user, ensuring accuracy over time and the operating temperature range.

LTC2754-16:16-Bit Quad SPI DAC Achieves ±1LSB INL & DNL with Software-Programmable Unipolar & Bipolar Outputs

Tue, 23 Jun 2009 10:50:15 -0700

The LTC2754 is a family of quad 12- and 16-bit multiplying serial-input, current-output digital-to-analog converters. They operate from a single 3V to 5V supply and are guaranteed monotonic over temperature. The LTC2754A-16 provides full 16-bit performance (±1LSB INL and DNL, max) over temperature without any adjustments. These SoftSpan DACs offer six output ranges (up to ±10V) that can be programmed through the 3-wire SPI serial interface, or pinstrapped for operation in a single range. The content of any on-chip register (including DAC output- range settings) can be verified in just one instruction cycle; and if you change any register, that register will be automatically read back during the next instruction cycle. Voltage-controlled offset and gain adjustments are also provided; and the power-on reset circuit and CLR pin both reset the DAC outputs to 0V regardless of output range.

LTC3803H-3: Flyback Controller Operates at 150°C Junction Temperature

Mon, 22 Jun 2009 16:02:57 -0700

The LTC3803 is a constant frequency current mode flyback controller optimized for driving 6V-rated N-channel MOSFETs in high input voltage applications. Constant frequency operation is maintained down to very light loads, resulting in less low frequency noise generation over a wide range of load currents. Slope compensation can be programmed with an external resistor. The LTC3803 provides ±1.5% output voltage accuracy and consumes only 240µA of quiescent current. Ground referenced current sensing allows LTC3803-based converters to accept input supplies beyond the LTC3803’s absolute maximum VCC. A micropower hysteretic start-up feature allows efficient operation at high input voltages. For simplicity, the LTC3803 can also be powered from a high VIN through a resistor, due to its internal 9.4V shunt regulator. An internal undervoltage lockout shuts down the LTC3803 when the input voltage falls below 4.6V, guaranteeing at least 4.6V of gate drive to the external MOSFET. The LTC3803 is available in a low profile (1mm) 6-lead SOT-23 (ThinSOT™) package.

LT3650-4.1/4.2: 32V Monolithic Li-Ion/Polymer Battery Chargers Deliver up to 2A in Compact 9mm2 Package

Mon, 22 Jun 2009 15:30:51 -0700

The LT3650 is a complete monolithic single-cell Li-Ion/ Polymer battery charger that operates over a 4.75V to 32V input voltage range (7.5V minimum start-up voltage). The LT3650 provides a constant-current/constant-voltage charge characteristic, with maximum charge current externally programmable up to 2A, set using an external current sense resistor. A precondition feature trickle charges a low voltage battery, and bad battery detection provides a signal and suspends charging if a battery does not respond to preconditioning. The LT3650 can be configured to terminate charging when charge current falls to C/10, or one-tenth the programmed maximum current. Once charging is terminated, the LT3650 enters a low current (85μA) standby mode. An auto-restart feature starts a new charging cycle if the battery voltage drops 2.5% from the fl oat voltage, or if a new battery is inserted into a charging system. The LT3650 contains a user-programmable internal safety timer (typically set to a three hour full cycle time). The IC can be configured to use this internal timer if a time-based termination scheme is desired in which charging can continue below C/10 until a desired time is reached. The LT3650 is available in a low profile (0.75mm) 3mm × 3mm 12-pin DFN package.

LTM9002: Dual-Channel uModule Receiver Subsystem Combines High-Speed ADCs & Drivers in Compact Package

Tue, 09 Jun 2009 16:55:04 -0700

The LTM9002 is a 14-bit dual-channel IF receiver subsystem. Utilizing an integrated system in a package (SiP) technology, it includes a dual high-speed 14-bit A/D converter, matching network, anti-aliasing filter and two low noise, differential amplifiers. It is designed for digitizing wide dynamic range signals with an intermediate frequency (IF) up to 300MHz. The amplifiers allow either AC- or DCcoupled input drive. Lowpass or bandpass filter networks can be implemented with various bandwidths. Contact Linear Technology regarding customization. The LTM9002 is perfect for demanding communications applications, with AC performance that includes 66dB SNR and 76dB spurious free dynamic range (SFDR). Auxiliary DACs allow gain balancing between channels. A single 3V supply allows low power operation. A separate output supply allows the outputs to drive 0.5V to 3.3V logic. An optional multiplexer allows both channels to share a digital output bus. Two single-ended CLK inputs can be driven together or independently. An optional clock duty cycle stabilizer allows high performance at full speed for a wide range of clock duty cycles.

LTC4012: 4A Multicell/Chemistry Battery Charger Controllers in Compact 16mm2 Package Require No Blocking Diode

Mon, 08 Jun 2009 14:13:49 -0700

The LTC4012 is a constant-current/constant-voltage battery charger controller. It uses a synchronous quasi-constant frequency PWM control architecture that will not generate audible noise with ceramic bulk capacitors. Charge current is set by external resistors and can be monitored as an output voltage. With no built-in termination, the LTC4012 family charges a wide range of batteries under external control. The LTC4012 features fully adjustable output voltage, while the LTC4012-1 and LTC4012-2 can be pin-programmed for Lithium-Ion/Polymer battery packs of 1-, 2-, 3- or 4-series cells. The LTC4012-1 provides output voltage of 4.1V/cell and the LTC4012-2 is a 4.2V/cell version. The device includes AC adapter input current limiting, which maximizes charge rate for a fixed input power level. An external sense resistor programs the input current limit, and the ICL status pin indicates reduced charge current as a result of AC adapter current limiting. Ideal diode control at the adaptor input improves charger efficiency. The CHRG status pin is active during all charging modes, including special indication for low charge current.

LTC3554: USB Power Manager & Dual Buck PMIC Optimized for Ultralow IQ

Thu, 04 Jun 2009 16:35:18 -0700

The LTC3554 is a micropower, highly integrated power management and battery charger IC for single-cell Li-Ion/Polymer battery applications. It includes a PowerPath manager with automatic load prioritization, a battery charger, an ideal diode and numerous internal protection features. Designed specifically for USB applications, the LTC3554 power manager automatically limits input current to a maximum of either 100mA or 500mA. Battery charge current is automatically reduced such that the sum of the load current and the charge current does not exceed the selected input current limit. The LTC3554 also includes two synchronous step-down switching regulators as well as a pushbutton controller. With all supplies enabled in standby mode, the quiescent current drawn from the battery is only 10μA. The LTC3554 is available in a 3mm × 3mm × 0.55mm 20-pin UTQFN package.