L6984 datasheet(19/34 Pages) STMICROELECTRONICS

19 / 34 page

DocID025378 Rev 3

19/34

L6984

Device description

Figure 12. The regulator works in CCM

3.5

Switchover feature

The switch over maximizes the efficiency at the light load that is crucial for LCM

applications.

The main switching controller is supplied by the VCC pin regulator

An integrated LDO regulates VCC = 3.3 V if VBIAS voltage is < 2.4 V.

VCC is connected to VBIAS through a MOSFET switch if VBIAS > 3.2 V and the embedded

LDO is disabled to increase the light load efficiency.

3.5.1

LCM

The LCM operation satisfies the requirements of battery powered applications where it is

crucial to increase the efficiency at the light load.

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.

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 11

where IQ OP VIN, IQ OP VBIAS are defined in Table 5: Electrical characteristics on page 7 and

L6984 is the efficiency of the conversion in the working point.

IQ VIN

IQ OP VIN



L6984

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

VBIAS

VIN

-------------- IQ OP VBIAS



L6984 Datenblatt(PDF) 19 Page - STMicroelectronics