Product News I Power Management
Synchronous step-down DC/DC controller delivers 95% efficiency
Linear Technology has introduced the LTC3839, a high frequency controlled on-time single output dual phase synchronous step- down DC/DC controller that can achieve up to 95% efficiency with a 25A output when operating at 2MHz. The operating frequency is selectable from 200kHz to 2MHz or can be synchronized to an external clock. A low 30ns minimum on-time allows for a high step-down ratio at very high operating frequencies. The controlled on-time,
valley current-mode architecture and Detect Transient Release feature provide a very fast transient response by increasing operating frequency during a transient event, enabling the output voltage to recover in only a few clock cycles. Up to 12 phases can be paralleled and clocked out of phase for high current applications (up to 250A).
The device operates over a 4.5V to 38V input voltage range, encompassing a wide variety of applications including most intermediate bus voltages. Strong onboard N-channel MOSFET gate drivers allow the use of high power external MOSFETs for output currents up to 50A, at output voltages ranging from 0.6V to 5.5V, making the device ideal for point-of-load requirements. The LTC3839’s differential amplifier provides true remote output voltage sensing of both the positive and negative terminals, enabling high accuracy regulation independent
of PCB IR losses (up to ±500mV). The output current is monitored by sensing the voltage drop across the output inductor (DCR) for highest efficiency or by using a sense resistor for extra precision. Additional features include an onboard bias voltage LDO, soft-start or tracking, adjustable current limit, overvoltage protection, current limit foldback and external VCC control. The LTC3839 offers total regulation accuracy and is specified to account for all error sources including line, load and differential sensing. Total output voltage accuracy is +/-0.25% at 25°C, +/- 0.67% from 0ºC to 85ºC, and ±1% maximum DC error over the full -40°C to 125°C operating junction temperature range and the LTC3839 is available in a thermally enhanced 5mm x 5mm QFN-32 package.
Linear Technology |
www.linear.com
XP Power extends line-up of miniature board mounted LED drivers
XP Power has extended its LDU series of PCB mount DC input constant current LED drivers. Comprising four models offering power outputs of 5, 7, 14 and 20 Watts, these efficient LED drivers have a typical efficiency of 93% for the 5 – 14 Watt models and 95% for the 20 Watt devices.
The LDU20 series provides up to 700 mA output current, and the LDU05, 07 and 14 series has a maximum output of 1000 mA. The drivers can accommodate a very wide range of input voltage from 7 – 30 VDC, which needs to be at least 2 V higher than the output. Dimming options include two analogue methods (voltage or resistance) and a pulse width modulation (PWM) input signal. The PWM approach has a maximum operating frequency of 1 kHz, with a minimum 200 ns on/off time. When using an analogue dimming method the output current range can be adjusted from 25% to 100% of nominal current. A remote on/off control input provides the
New converters from Powersolve feature high power density
New from Powersolve the THL-20WI series of DC/DC converters have been designed to provide 20W from a metal package measuring just 25.4 x 25.4mm with the industry standard pinout. Height off the board is just 10.2mm. With an ultra-wide 4:1 input voltage range of either 9-36VDC or 18-75VDC, the Traco Power THL-20WI series features adjustable output voltages from 3.3 to 15V and an operating temperature range of -40ºC to +75ºC
The new DC/DC converters feature short
circuit protection, remote on/off, input/output- isolation specified to 1500VDC and an input filter which meets EN 55022, class A.
Powersolve Electronics |
www.powersolve.co.uk
designer the ability to control the output or sequence the start-up. All models provide protection in the event of a short or open circuit of the LED device.
The LDU series suit a broad range of indoor,
outdoor, underwater and automotive LED lighting application and are also suitable for battery powered applications.
XP Power |
www.xppower.com
www.cieonline.co.uk
Components in Electronics
February 2012 41
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