Operates with power blocks and DrMOS devices

February 8, 2012 – Linear Technology Korea (CEO Hong Sa-kwak) announced the release of the dual-output synchronous step-down DC/DC controller (Product Name: LTC3861), featuring multiphase operation, differential output voltage sensing, and high-frequency operation. This controller enables more flexible design configurations by integrating with external powertrain devices, such as power blocks and DrMOS, as well as discrete N-channel MOSFETs and associated gate drivers. Up to 12 phases can be connected in parallel and reverse-phase clocked to minimize I/O filtering to meet very high current requirements (up to 300A). Key applications include high-current power distribution and industrial systems, as well as DSP and ASIC supplies.
The LTC3861's current sharing loop enables precise current sharing by pacing multiple ICs, even during DC and load transients. The device's voltage mode control architecture allows for selectable fixed operating frequencies from 250 kHz to 2.25 MHz and can be synchronized within the same range using a phased-lock loop (PLL). The differential amplifier enables true remote output voltage sensing for both the VOUT and ground terminals, allowing for high-precision regulation. The LTC3861 operates with VCC voltages ranging from 3 V to 5.5 V and VIN voltages (drain voltages for high-side MOSFETs) from 3 V to 24 V, generating output voltages from 0.6 V to 5 V. Output current sensing is achieved by monitoring the voltage drop (DCR) across the output inductor or by using a sense resistor for maximum efficiency. The current limiting function is adjustable and can be configured for very low sensing voltage (up to 50mV) to minimize power loss.
Other features include adjustable soft start or tracking, output voltage protection, and two Power Good output signals. In addition, this product can maintain a reference voltage accuracy of 1% over an operating temperature range of -40°C to 125°C.
The LTC3861 is available in a 36-pin 5mm x 6mm QFN package and is available for immediate purchase. Pricing starts at $2.88 per unit for orders of 1,000. For more information, please visit www.linear.com/product/LTC3861 .

Image caption: Dual synchronous step-down DC/DC controller

Product Features: LTC3861
• Can be used with power blocks and DrMOS devices
• Multi-phase operation function with precise current sharing (up to 12 phases)
• Differential amplifier for remote voltage sensing
• VCC Range: 3V ~ 5.5V
• VIN Range: 3V ~ 24V
• Very fast transient response speed
• Fixed operating frequency with phase locking capability from 250kHz to 2.25MHz
• DCR or RSENSE output current sensing
• Adjustable current limit
• Voltage mode control
• Dynamic current sharing between faces
• Adjustable soft start or tracking
• ±1% reference voltage accuracy in the range of -40°C to +125°C
• Powerful output