Demo circuit 2637A features four LT3045EDD-1s in parallel, generating an ultralow noise, ultrahigh power supply rejection ratio (PSRR) low dropout (LDO) regulator with programmable current limit. DC2637A operates over an input range of 3.8V to 20V, and is capable of delivering up to 2A output current by paralleling four LT3045EDD-1s with only 20mΩ ballast resistors.
The VIOC tracking function of the LT3045EDD-1 controls an upstream switching converter to maintain a constant voltage across the regulator and hence minimize power dissipation. In the parallel configuration, connect the VIOC pin of only one IC to the switching converter, while the VIOC pins of the other ICs are left floating. The power good feedback (PGFB) pin is used to set a programmable power good threshold, and also activates the fast start-up circuitry. The PGFB is set on only one IC when they are paralleled. LT3045-1 also offers programmable current limit functionality by connecting a resistor from ILIM to GND on each device. Current monitoring is also achieved by sensing the ILIM pin voltage.
Built-in protection includes reverse battery protection, reverse current protection, internal current limit with fold-back, and thermal limit with hysteresis.
The LT3045-1 data sheet gives a complete description of the device, operation and applications information. The data sheet must be read in conjunction with this demo manual for demonstration circuit 2637A. The LT3045EDD-1 is assembled in a 12-lead (3mm × 3mm) plastic DFN package with an exposed pad on the bottom-side of the IC. Proper board layout is essential for maximum thermal performance.