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LDO Regulator Application Note

The ECO Function

ECO Function

An ECO Function is a function developed by the concept of realizing a High-performance Type Regulator and a Low Supply Current Type Regulator integrated in a single chip. This is a function for a mobile phone for example which has three operating modes instead of only two; Talk mode, Standby mode and an Off mode.
The LDO regulator with ECO function is able to switch between a fast response mode (high-performance) and a low power mode (low supply current), additionally it can be switched to the Off mode by the CE pin.
The regulator with ECO function has the advantage of combining features of both a High-performance Type and a Low Supply Current Type which reduces the number of parts on the board space.

Comparison of Supply Current

The electrical characteristics of the supply current of a Low Supply Current Type Regulator, a Regulator with ECO Function and a High-performance Type Regulator are shown in below table.

Low Supply Current Type RP110x	With ECO Function RP201x	High-performance Type RP112x
Typ. 1µA	Low Power Mode : Typ. 1.5µA Fast Response Mode : Typ. 55µA	Typ. 75µA

Comparison of Ripple Rejection Ratio

The ripple rejection ratio graph of a Low Supply Current Type Regulator, a Regulator with ECO Function and High-performance Type Regulator. (Since the measurement conditions may be slightly different, please consider below graphs as a reference)

Comparison of Ripple Rejection Ratio

Comparison of Load Transient Response

The load transient response graph of a Low Supply Current Type Regulator, a Regulator with ECO Function and High-performance Type Regulator. (Since the measurement conditions may be slightly different, please consider below graphs as a reference)
Please note that the scale of the horizontal-axis for Low Supply Current Type and a Low Power Mode are in "ms", while those of a High-performance Type and a Fast Response Mode are in "µs", the load transient response is more than 100 times faster and output voltage variations are suppressed to 1/10.

Comparison of Load Transient Response