In addition to previously launched (manual) 3-Mode and Seamless LDOs, Ricoh has developed another unique alternative solution to save power consumption in order to extend the battery life of an application. With basic LDOs one can only choose between either low power or low noise types. By using the Automatic Mode Shift LDO, one can take advantage of both basic LDO features without the need for additional control pins and software to switch between operating modes. An embedded detection circuit monitors the output current demand of the application. The 3-Mode feature is particularly interesting for applications with various operating modes, such as mobile communication or other battery operated devices. 

Below you can find an example of how to obtain 3 operating modes: 
1. Output current increases above 3 mA; the LDO is set to Fast Transient Mode.
2. Output current decreases below 0.6 mA; the LDO is set to Low Power Mode.
3. Controlling the CE pin sets the LDO to Off Mode for minimum power 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 R5326x 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 R5326x is already prepared for that as the output voltage setting ranges from 0.8 V to 4.2 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 a low ESR value in a range from 1.0 µF to 3.3 µF can be used. The capacitor value depends on input and output voltage conditions. The R5326x is available in a SOT23-6 or PLP1820-6 package. When a small circuit board area is important, the R5326x also comes in a convenient, ultra tiny WL-CSP-6 package. A single version of the Automatic Mode Shift LDO is currently under development. 

R5326 features (VR1, VR2):