In addition to the successful, earlier launched single 3-Mode LDO R1160 series, Ricoh has developed a dual version called R5328K. With basic LDOs, one can only choose between either low power or low noise types. By using a 3-Mode LDO with ECO pin, one can take advantage of both basic LDO features. This feature is particularly interesting for applications with various operating modes, such as mobile communication or other battery operated devices. 

Below you can find and example of how to obtain 3 operating modes:
1. ECO pin high; LDO in Fast Transient Mode (high ripple rejection / high supply current).
2. ECO pin low; LDO in Low Power Mode (moderate ripple rejection / low supply current).
3. CE pin low; LDO in Off Mode (minimum current consumption).

Another remarkable feature is the LDO’s ability to operate at very low input voltages. This can be important when multiple supply voltages are required in an application. In case output voltages below 2.0 V are required, it might become difficult to combine multiple power management ICs connected in series, since older generation LDOs have a minimum operating voltage of approximately 2.0 V. The R5328K can operate in a range from 1.4 V to 6.0 V and a solution such as connecting the input to a 1.8 V supply and providing an output voltage of 1.2 V or even lower is possible. 

The next processor generation can require low supply voltages of 1.0 V or even lower. The R5328K is already prepared for that as the output voltage setting ranges from 0.8 V to 4.0 V. As for protection, an embedded fold-back current limit circuit decreases the output current in case of a short circuit to approximately 50 mA. This protects the LDO and other electronic parts of the application from damage. An optional feature is the auto discharge function, which discharges the output capacitor fast once the LDO is disabled. This avoids odd behaviour of the application, such as random graphics on the display or odd sounds from the speaker, during the power down sequence. For stable operation, small ceramic capacitors with low ESR and a minimum value of 1.0 µF can be used. The R5328K is available in a PLP2020-8 package only and is convenient to use on high density and small circuit boards.

R5328K features (VR1, VR2):