Linear Technology LTC3833 step-down DC/DC controller

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Linear Technology has introduced the LTC3833, a high-frequency controlled, on-time synchronous step-down DC/DC controller with differential output voltage sensing and clock synchronisation.

The controlled on-time, valley current-mode architecture forces a fast transient response by increasing its operating frequency during a transient event, allowing it to recover from a large load step in only a few cycles.

Its 4.5 to 38 V input range encompasses 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 high load current, up to 25 A in applications with output voltages ranging from 0.6 to 5.5, making it suitable for point-of-load requirements.

The device’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 ±500 mV) in trace runs, vias and interconnects. A low 20 ns minimum on time allows for a high step-down ratio power supply at high-frequency operation.

The operating frequency is selectable from 200 kHz to 2 MHz or can be synchronised to an external clock. The output current is monitored by sensing the voltage drop across the output inductor for highest efficiency or by using a sense resistor.

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 controller offers total differential regulation accuracy and is specified to account for all error sources, including line, load and differential sensing. Its total differential output voltage accuracy is ±0.25% at 25°C, ±0.67% from 0 to 85°C and ±1% over the full -40 to 125°C operating junction temperature range.