Demonstration circuit 518 is a positive input to negative output SLIC (Subscriber Line Interface Circuit) converter featuring the LTC3704 switching controller. DC518 converts 4.5V to 15V input to –24V and –70V output and provides over 200mA of output current from a 5V input. The converter operates at 200kHz with high efficiency of up to 92%. The DC518 is set to operate with current sense resistor RS1 and input voltages up to 15V. However, DC518 can be modified for No- RsenseTM operation with a 5V input voltage, provided that MOSFET drain voltage does not exceed 36V (main output set between 0V and -24V). The circuit features an optional soft-start circuit that can be enabled or disabled with a single jumper. DC518 has a jumper to program either continuous or Burst-Mode operation and can be synchronized to an external clock of up to 400kHz. Please refer to the LTC3704 data sheet for design details and applications information.