True Current Mode Control featuring sub-mΩ DCR Sensing Capability

February 15, 2012 – Linear Technology Korea (CEO Hong Sa-gwak) announced the launch of a current mode synchronous step-down DC/DC controller (product name: LTC3866). This product utilizes a new DCR sensing architecture to enable the use of very low DC resistance power inductors, thereby improving the signal-to-noise ratio of current sensing signals. With a power inductor DC resistance as low as 0.17mΩ, it can be utilized to maximize converter efficiency and increase power density. This new DCR sensing technology significantly reduces switching jitter commonly associated with low DCR resistance applications. The DCR temperature compensation function maintains consistent and accurate current limit thresholds across a wide temperature range.
The LTC3866 operates over an input voltage range of 4.5V to 38V, enabling its use in a wide range of applications including most intermediate bus voltages and battery voltages. The powerful onboard N-channel MOSFET gate driver can accommodate high-power external MOSFETs, DrMOS devices, or power blocks to deliver up to 40A of output current with output voltages from 0.6V to 5V. The LTC3866 can be paralleled for high-power multiphase applications. The onboard differential amplifier provides remote output voltage sensing for both positive and negative terminals, implementing precision regulation regardless of IR losses in trace runs (up to ±500mV). Low current sensing threshold is selectable in the range of 10mV to 30mV. Fixed operating frequency is adjustable from 250kHz to 770kHz or can be synchronized with an external clock. Additional features include an internal bias voltage regulator, soft-start or tracking, overvoltage protection, soft short-circuit recovery, current limit foldback, thermal shutdown, and external VCC control functions.
The LTC3866 operates over a junction temperature range of -40°C to 125°C and is available in 4mm x 4mm QFN-24 and TSSOP-24E packages with enhanced thermal performance. Pricing for this product starts at $2.71 per unit based on quantities of 1,000 pieces. For detailed information, refer to www.linear.com/product/LTC3866.
Photo caption: Sub-mΩ DCR Sensing Step-Down DC/DC Controller

Product Features: LTC3866

• Sub-mΩ Resistance DCR Current Sensing – Provides very low jitter at 0.17mΩ level
• New DCR Sensing Current Mode Control Function
• DCR Temperature Compensation
• Support for Discrete, DrMOS, and Power Block Power Stages
• High-Speed Differential Remote VOUT Sensing Amplifier
• Wide Input Voltage Range: 4.5V to 38V
• Output Voltage Range: 0.6V to 5V
• Current Sensing Threshold Adjustment Range: 10mV to 30mV
• Fixed Operating Frequency Selectable from 250kHz to 770kHz
• Soft-Start with Output Voltage Tracking or Programmable Capability
• Overvoltage Protection and Thermal Shutdown Functions
• Soft Short-Circuit Recovery Function