In summary, the Linear Technology LT8709 is a negative input synchronous multi-topology DC/DC controller that can be used for negative-to-negative or negative-to-positive DC/DC power conversion. Capable of being configured in buck, boost, buck-boost, and inverting topologies, the LT8709 operates over a -4.5V to -80V input voltage range and produces an output voltage from -0.1V to 60V or -1.4V to -80V. A high efficiency P-channel MOSFET replaces the output diode in synchronous operation, increasing efficiency and allowing for a higher output current. The LT8709 features rail-to-rail output current monitor and control which enables the device to be configured as a current source. An EN/FBIN circuit is supported for slowly varying input signals and can be used for input voltage regulation with a high impedance supply. The LT8709 is available in a 20-lead TSSOP package.