Technical Information Site of Power Supply Design

Product Key Points

Nano Cap™ Technology Enabling Stable Control with Nano-order Output Capacitances

Realization of a Linear Regulator that Effectively Eliminates Output Capacitors

  • No need for a linear regulator output capacitor
  • Stable control with an output capacitance of 100 nF (0.1 µF)
  • 1/10 or less
  • ±3.6% for Nano Cap equipped device
  • Exceptional load transient response of ±3.6%
  • Stable operation without an output capacitor

"Nano Cap™" is a proprietary ROHM power supply technology that achieves stable control even when the output capacitance of a power supply circuit is on the order of nanofarads (nF). In an example of a linear regulator provided with Nano Cap technology, stable control is made possible with an output capacitance of 100 nF (0.1 μF), so that if a bypass capacitor (generally 100 nF) is present at the power supply pin of an ordinary load (a microcontroller or other IC), the need for a linear regulator output capacitor is effectively eliminated.

< Features of Linear Regulators Provided with Nano Cap Technology >

  • ・No need for a linear regulator output capacitor. (For cases in which there is a 100 nF (0.1 μF) capacitor on the load side)
  • ・Load transient response characteristic is dramatically improved compared with conventional products featuring low output capacitances
  • ・Elimination of an output capacitor contributes to smaller footprints, reduced costs
  • ・Hereafter Nano Cap technology will be expanded for use in other analog ICs such as op-amps and LED drivers (some samples are currently being shipped)

Nano Cap Technology Eliminates the Need for a Linear Regulator Output Capacitor

Nano Cap is a power supply technology that combines three ROHM techniques for analog circuits in the areas of circuit design, layout, and processes. Through improvement of response performance in analog circuits and by eliminating to the extent possible parasitic components in internal circuits due to internal wiring, amplifiers and the like, output capacitor values can be reduced to 1/10 or less those in conventional devices.

For example, when the power supply for a microcontroller (MCU) is supplied by a linear regulator, normally a 1 μF output capacitor is connected to the output of a conventional linear regulator and a 100 nF (0.1 μF) bypass capacitor is connected at (close to) the power supply pin of the MCU. In contrast, when using a linear regulator provided with Nano Cap, only the 100 nF bypass capacitor on the MCU side is needed for stable operation.

Load Transient Response Dramatically Improved Even with a 100nF Output Capacitance

Shown below is a comparison of the load transient responses for a linear regulator equipped with Nano Cap and a conventional linear regulator supporting a 100 nF output capacitance. Characteristics are compared for output capacitors of 1 μF and 100 nF given an output voltage of 5 V and load fluctuation of 50 mA.

With an output capacitor of 100 nF, whereas the output voltage fluctuation of the conventional linear regulator was ±15.6%, the linear regulator provided with Nano Cap exhibited an exceptional load transient response of ±3.6%. The standard requirement for load transient response is held to be ±5%, and it is seen that this requirement is easily satisfied. Hence if a 100 nF capacitor is added on the load side, a linear regulator provided with Nano Cap is effectively capable of stable operation without an output capacitor.

Power Supply Design Technical Materials Free Download

Power Supply Design Technical Materials Free Download

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