Monolithic synchronous step-down regulator
10 January 2012
24V, 15A monolithic synchronous step-down regulator with differential output sensing and clock synchronisation.
Linear Technology’s LTC3613 is a high frequency controlled on-time synchronous step-down DC/DC converter with differential output voltage sensing and clock synchronisation. The controlled on time, valley current mode architecture enables a very fast transient response by increasing its operating frequency during a transient event, allowing the LTC3613 to recover from a large load step in only a few clock cycles.
Its 4.5V to 24V input range supports a variety of applications, including most intermediate bus voltages. Integrated N-channel MOSFETs can deliver continuous load currents as high as 15A at output voltages ranging from 0.6V to 5.5V, making it ideal for point-of-load applications.
The LTC3613’s differential amplifier provides true remote output voltage sensing of both the positive and negative terminals, enabling high accuracy regulation independent of IR losses (up to ±500mV) in trace runs, vias and interconnects. A low 65ns minimum on time allows for a high step-down ratio power supply at high frequency operation. The operating frequency is selectable from 200kHz to 1MHz and can be synchronised to an external clock. The output current is monitored by sensing the voltage drop across the output inductor’s DCR for highest efficiency or by using a sense resistor. Additional features include an onboard bias voltage LDO, soft-start or tracking, overvoltage protection, current limit foldback and external VCC control.
The LTC3613 offers superior total differential output regulation accuracy and is specified to account for all error sources including line, load and differential sensing. The LTC3613’s total differential output voltage accuracy is +/-0.25% at 25°C, +/-0.67% from 0ºC to 85ºC and ±1% over the full -40°C to 125°C operating junction temperature range. The LTC3613EWKH is available in a thermally enhanced 7mm x 9mm QFN-56 package. An industrial temperature grade version, the LTC3613IWKH, is also available.
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