Ricoh Europe Semiconductor Support Centre, has launched the RP110 Low Supply Current LDO Regulator, a LDO with a newly designed constant slope circuit for an enhanced start-up sequence. The RP110 Low Supply Current LDO Regulator features 1µA current consumption and can consume even less than 1µA in the version without a CE pin.

Major improvements have been made in high output voltage accuracy, compared to previous products. The minimum input voltage capability of RP110 is measured at 1.4V, making this particular LDO highly suitable to cascade it with other power management ICs to create various supply voltages. Most current LDOs initiate the op-eration with the input voltage starting from 2.0V or more. It is preferable to use the RP110 in circuits with a power saving mode (requiring a standby voltage) as well as circuits with less demanding ripple rejection performance.

A new added feature for this device is a Constant Slope Circuit which enables a soft-start function for the LDO. When the LDO is turned on by the chip enable pin, the output voltage will increase to the desired level gradually. The constant slope circuit minimizes a large inrush current caused by output capacitors, and prevents an over-shoot of the output voltage during the start-up period. No additional external parts are required for this soft-start function, saving valuable circuit board space.

The soft-start delay time and the start-up slope angle are fixed internally. The level of the soft-start period depends on the output capacitor specifications – for capacitors above 4.7µF the current limit circuit will cause a longer start-up period. The RP110 has an embedded fold back current limit circuit, which contributes to the decrease of the output current to the level of 50mA when a short circuit occurs, pro-tecting the LDO as well as other electronic parts from possible damage.

Small ceramic capacitors with low ESR and a minimum value of 1µF are used to ensure stable operation. Optional features include an auto-discharge function which secures the fast discharge of the output capacitor once the LDO is disabled, removing any possible phenomena of the application such as random graphics shown on the display or strange sounds from the speaker during the power down sequence.

The RP110 is available in regular packages: SOT23-5 and SC-88A, as well as in re-markably small DFN1010-4 and the new ultra tiny DFN(PLP)0808-4, which are con-venient to use on high density or small circuit boards.