LDO Regulator Application Note
The 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
|With ECO Function
|Typ. 1µA||Low Power Mode : Typ. 1.5µA
Fast Response Mode : Typ. 55µA
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 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.