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LDO Linear RegulatorsDC/DC Switching RegulatorsHow to use
LDO's supply current is an operating current for the LDO itself. It does not include the current supplied to or driving other devices.
As for the input current, 100% load current also flows from input power source. In a CMOS-based linear regulator, as shown in the figure 1, the supply current is flowing to the LDO controlling circuit, equal to input curret minus load current.
Figure 1. Supply current of IC itself
Figure 2. RP109 series Block Diagram
On the other hand, generally, LDO has an individual pin for control On and Off of the LDO. As shown in the Figure 2, CE is the chip enable pin and control On and Off of the LDO. Standby current is the current at shutdown. (At shut down, LDO turns off by CE control).
At the standby state, the controlling circuit becomes off, so the output voltage also becomes 0 V (OFF).
If output discharge function is included in the LDO, output voltage is pulled down to GND by the discharge transistor and discharged by the load. Otherwise, the output voltage is pulled down with LDO's internal high divider resistors and discharged by the load.