The DC1771A is a single output synchronous buck converter featuring the LTC®3867EUF with a 24-lead 4mm × 4mm QFN package. Using the inductor’s DCR as the sense element instead of the on-board sense resistor saves cost and board space while improving full-load efficiency over 2%, though the sense resistor provides a more accurate current limit. The board has a lot of features including an internal 5V linear regulator for bias, output voltage remote sense, programmable nonlinear control to improve load tran- sient performance, programmable thermal shutdown, optional temperature compensated DCR sense circuit, a mode selector that allows the converter to run in CCM, pulse-skipping or Burst Mode® operation. Synchronization to an external clock is also possible. The input voltage range is from 4.5V to 14V. The LTC3867 data sheet gives a complete description of the part, op- eration and application information and must be read in conjunction with this demo manual for DC1771A. Design files for this circuit board are available at http://www.linear.com/demo.
The DC1771A is a demonstration circuit board configured with the LTC3867EUF synchronous buck converter. It features a single output with an optional temperature compensated DCR sense circuit, allowing for cost and space savings while improving efficiency. The board includes an internal 5V linear regulator for bias and supports programmable nonlinear control to improve load transient performance.
| Input Voltage Range | 4.5V ~ 14V |
|---|---|
| Output Voltage | 1.5V ±2% |
| Default Operating Frequency | 400kHz |
| External Clock Sync. Frequency Range | 400kHz to 780kHz |
| Typical Full-Load Efficiency | 88.3% |
Change the JP3 jumper position to select CCM, BURST, or P.S. for forced continuous conduction, burst, or pulse-skipping mode respectively.
The onboard soft-start circuit allows the soft-start ramp rate to be adjusted by changing the value of capacitor C24.