Demo circuit DC2952A features the LT3093, an ultralow noise, ultrahigh power supply rejection ratio (PSRR) negative low dropout (LDO) regulator. DC2952A operates over an input range of –3.8V to –20V, and can deliver up to 200mA output current. It features ultralow noise (0.8µVRMS from 10Hz to 100kHz) and very high PSRR (73dB at 1MHz).
The EN/UVLO of LT3093 is bidirectional and can be switched with either a positive or a negative voltage. LT3093 also offers programmable current limit functionality by connecting a resistor from ILIM to GND. The VIOC tracking function controls an up-stream switching converter to maintain a constant voltage across the regulator and hence minimize power dissipation. The power good feedback (PGFB) pin is used to set a programmable power good threshold, and activates the fast start-up circuitry. To use the power good function, connect an external voltage source at VEXT. If power good and fast start-up functionality are not needed, tie PGFB to IN.
Built-in protection includes internal current limit with foldback and thermal limit with hysteresis.
The LT3093 datasheet gives a complete description of the part, operation and applications information. The datasheet must be read in conjunction with this Demo Manual for demonstration circuit DC2952A. The LT3093 is assembled in 12-lead MSOP and 3mm x 3mm DFN packages with an exposed pad on the bottom-side of the IC. Proper board layout is essential for maximum thermal performance.