In terms of on-resistance/dropout voltage value, these two new LDOs have an excellent performance: only 0.18 Ω on-resistance respectively and 180 mV dropout voltage at 1,000 mA output current. They extend battery life especially for battery operated applications and prevent high heat dissipation or large heat sinks on the circuit board.

Another remarkable feature is the ability to operate at very low input voltages, which can be important, if, for example, multiple supply voltages are required in an application for either a single or individual circuits. In case output voltages below 2.0 V are required, it becomes difficult to combine multiple power management ICs connected in series, since most other competitive LDOs start to operate from around 2.0 V. The R1172x and R1173x can operate in a range from 1.4 V to 6.0 V and the power supply can be designed in the most efficient way by connecting the LDO input directly to an output of another power management IC, thus avoiding large differential voltages between LDO input and output and causing more heat dissipation at a reasonable output current.

Throughout the years there has been a decreasing trend for the supply voltage level requirement of processors; most likely, supply voltages of 1.0 V and below might be required soon for the next processor generation. The R1172x and R1173x are already prepared for that: any fixed output voltage setting from 0.8 V up to 5.0 V is possible and can be ordered in a 0.1 V increment, even an adjustable version is available. 

The new LDOs offer a high ripple rejection performance of 70 dB in combination with a low supply current level of 60 µA. Also the excellent load regulation is typical: only -3 mV and maximum ±20 mV at a load of 1,000 mA. Various protection features are embedded, protecting the LDO and other electronic parts of the application. A fold-back current limit circuit decreases the output current in case of a short circuit down to ±50 mA, thermal protection prevents overheating and the in-rush suppression circuit limits the output current to 500 mA during power-up.

3 versions are available depending on the preference of the CE pin active level or the requirement of an additional auto-discharge transistor connected to the LDO output. This feature discharges the LDO output capacitor rapidly when it is turned off and avoids odd behaviour of the application during the power down period.

R1172x and R1173x Features