L6985F datasheet(28/65 Pages) STMICROELECTRONICS

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Functional description

L6985F

28/65

DocID027836 Rev 2

Figure 20. The regulator works in CCM

4.6

Switchover feature

The switchover maximizes the efficiency at the light-load that is crucial for LCM applications.

4.6.1

LCM

The LCM operation satisfies the high efficiency requirements of the battery powered

applications. In order to minimize the regulator quiescent current request from the input

voltage, the VBIAS pin can be connected to an external voltage source in the range

3 V < VBIAS < 5.5 V (see Section 4.1: Power supply and voltage reference on page 13).

In case the VBIAS pin is connected to the regulated output voltage (VOUT), the total current

drawn from the input voltage can be calculated as:

Equation 14

where IQ OP VIN, IQ OP VBIAS are defined in Table 5: Electrical characteristics on page 8 and

L6985F is the efficiency of the conversion in the working point.

4.6.2

LNM

Equation 14 is also valid when the device works in LNM and it can increase the efficiency at

the medium load since the regulator always operates in the continuous conduction mode.

IQVIN

IQOPVIN



L6985F

--------------------

VBIAS

VIN

--------------- IQOPVBIAS



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