linear technology corp (LLTC) Key Developments
Linear Technology Unveils LTM4634 Step-Down µmodule Regulator
Sep 3 14
Linear Technology Corporation has introduced the LTM4634, a triple output step-down µModule, or micromodule, regulator in a 15mm x 15mm x 5.01mm ball grid array, or BGA, package with integrated heat sink. The thermally efficient package enables the LTM4634 to deliver full current on all three outputs (5A, 5A, and 4A), more than 70W of output power at 65°C ambient with 200LFM airflow. Combined with only 13 ceramic capacitors and three resistors, the LTM4634 solution fits within 4.5cm² on a dual-sided PCB. The LTM4634 includes three DC/DC controllers, power switches, inductors and compensation in a single package. The regulated output voltage for channels 1 and 2 is adjustable between 0.8V to 5.5V, with the third channel from 0.8V to 13.5V, each with ±1.5% accuracy over line, load and temperature. The combination of wide output voltage range, a thermally efficient package, tight regulation accuracy and small solution size makes the LTM4634 well suited to regulate common intermediate power buses such as 12V, 5V and 3.3V in instrumentation, communications and industrial applications. The LTM4634's three switchers operate from an input voltage from 4.75V to 28V. Separate input power pins for each switcher enables channel one and/or channel two to be supplied from a 12.5V, 50W intermediate bus generated from channel three. The three switchers, operating from the same internal or optional external clock signal, are internally phase shifted by 120° to minimize input ripple. For loads in excess of 5A, channels 1 and 2 can be paralleled to support up to 10A. Output overvoltage and over current fault protection are included in the regulator. The LTM4634's internal temperature can be observed via two internal temperature diode monitors located next to the power stages. The LTM4634 is available in the -40°C to +125°C internal operating temperature grade for immediate delivery from stock.
Linear Technology Introduces LTC4231 Hot Swap Controller
Sep 2 14
Linear Technology Corporation has introduced the LTC4231, an ultralow quiescent current IQ Hot Swap controller, reportedly enabling safe board or battery insertion and extraction from 2.7V to 36V systems. The LTC4231 controls an external N-channel MOSFET to gently power up board capacitors, avoiding sparks, connector damage and system glitches. Device quiescent current is a mere 4 microampere during normal operation, dropping to 0.3A in shutdown mode. To ensure low current operation, the under voltage and overvoltage resistive dividers are connected to a strobed ground, lowering their average current draw by 50x. The LTC4231 provides a compact and rugged micropower solution for hot plugging and battery protection, especially in energy conscious applications utilizing solar power or energy harvesting. The LTC4231 survives and also protects downstream circuitry from reversed batteries up to -40V by controlling back-to-back N-channel MOSFETs. Undervoltage protection cuts off low voltage batteries to prevent deep discharge, while adjustable hysteresis avoids oscillations from battery recovery after load removal. Dual level overcurrent protection is provided by a timed circuit breaker and fast current limit. The 2.7V to 36V operating range accommodates a wide range of battery chemistries including lead-acid, Li-Ion and stacked NiCd. The LTC4231 is available in two options: the LTC4231-1 remains off after an overcurrent fault, whereas the LTC4231-2 automatically attempts to turn on after a 500ms cooldown period. Specified over the 0°C to 70°C commercial and -40°C to 85°C industrial temperature ranges, the LTC4231 is offered in 12-pin MSOP and 3mm x 3mm QFN packages. 1,000-piece pricing starts at $2.25 each. Device samples and evaluation circuit boards are available online or from your local Linear Technology sales office.
Linear Technology Introduces LT8310 Controller
Sep 1 14
Linear Technology Corporation has introduced the LT8310, a primary-side synchronous forward controller. The LT8310 operates over an input voltage range of 6V to 100V, is targeted for power levels up to 200W and provides a drive signal for secondary-side synchronous rectification to improve efficiency. Output voltage regulation of +/-8% can be attained without the use of an opto-coupler. When an opto-coupler is used, +/-1.5% regulation can be realized. A programmable volt-second clamp provides a safeguard for transformer reset that prevents saturation and protects the MOSFET. This function optimizes the transformer and MOSFET, reducing solution size. The LT8310 computes the duty cycle required to create a constant VOUT in open loop applications, thereby simplifying the design. In closed loop applications, the LT8310 limits maximum VOUT if the opto-coupler path breaks open. Additional features include programmable overcurrent protection, adjustable input undervoltage, overvoltage lockout and built-in thermal shutdown. The LT8310 has a programmable 100kHz to 500kHz operating switching frequency and can be synchronized to an external clock, enabling the use of a wide range of output inductor values and transformer sizes. The LT8310 is available in a TSSOP-20 package with several pins removed for high voltage spacing. The LT8310 E- and I-grade versions operate from a -40Â°C to 125Â°C junction temperature. The LT8310 H grade is guaranteed to operate from a -40Â°C to 150Â°C operating junction temperature. The LT8310 MP grade is guaranteed to operate from -55Â°C to 150Â°C operating junction temperature.
Linear Technology Corporation Introduces LTC3807 Synchronous Step-Down Controller
Sep 1 14
Linear Technology Corporation announced that it has introduced the LTC3807, a low quiescent current synchronous step-down DC/DC controller that draws only 50 microampere in standby mode with the output voltage in regulation. The 4V to 38V input supply range is designed to protect against high voltage transients, continue operation during automotive cold crank and cover a broad range of input sources and battery chemistries. The output voltage can be set from 0.8V to 24V at output currents up to 25 amps with efficiencies as high as 95%, making it well suited for automotive, heavy equipment, industrial and robotic applications. The LTC3807 has powerful 1.1 Ohm on-chip MOSFET gate drivers. It operates with a selectable fixed frequency between 50kHz and 900kHz and is synchronizable to an external clock ranging from 75kHz to 850kHz. The user can select from continuous operation, pulse skipping and low ripple Burst Mode operation during light loads. Its current-mode architecture provides easy loop compensation, fast transient response and excellent line regulation. Output current sensing is accomplished by measuring the voltage drop across the output inductor (DCR) for the high efficiency or by using an optional sense resistor. Current foldback limits MOSFET heat dissipation during overload conditions. Additional features include a low 95ns minimum on-time for high step-down ratios, up to 99% duty cycle for low voltage dropout, an internal LDO that powers the gate drivers and a power good signal. The LTC3807 is available in 20-pin 3mm x 4mm QFN and 20-lead TSSOP thermally enhanced packages. Four temperature grades are available, with operation from -40 to 125°C for the extended and industrial grades, a high temp automotive range of -40°C to 150°C and a military grade of -55°C to 150EC.
Linear Technology Corporation Introduces LTC2645 Digital-To-Analog Converter
Aug 21 14
Linear Technology Corporation has introduced the LTC2645, a quad-channel 12-bit/10-bit/8-bit PWM-to-voltage output digital-to-analog converter, or DAC, with 10ppm/Â°C reference. These parts convert PWM input signals to 12-bit accurate, stable, buffered voltage outputs in less than 8Âµs, eliminating the ripple and delay typically associated with analog filters. The LTC2645 provides a simple bolt-on solution to accurately set and adjust four voltages without a single line of code required. Offered in a small 16-lead MSOP package, the LTC2645 is ideal for biasing, calibration, level setting, power supply adjustment, and to enable opto-isolated communications in applications such as industrial automation, 4-20mA process control, instrumentation, test equipment and optical modules. A dual version, the LTC2644, is available in a 12-lead MSOP package. The LTC2645 measures the period and pulse width of the PWM input signals and updates the DACs after each PWM input rising edge, accepting PWM input frequencies from 30Hz up to 100kHz. An IDLSEL pin provides flexibility to set the outputs to idle at zero- or full-scale, power-down with high-impedance output, or hold the previous state indefinitely in response to an idle PWM input. This convenient mode has the advantage over analog filter implementations, which require the PWM to run continuously. Each rail-to-rail DAC output is capable of sourcing or sinking 5mA (3V) or 10mA (5V), and offers a full-scale output of 2.5V using the internal 10ppm/Â°C reference or a full-scale output equal to the external reference. The LTC2645 operates from a single 2.7V to 5.5V supply, and supports PWM input voltages from 1.71V to 5.5V.