A6986F datasheet(25/72 Pages) STMICROELECTRONICS

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A6986F

Functional description

5.5

Light-load operation

The MLF pinstrapping during the power-up phase determines the light-load operation (refer

to Table 7 on page 11 and Table 8 on page 12).

5.5.1

Low noise mode (LNM)

The low noise mode implements a forced PWM operation over the different loading

conditions. The LNM features a constant switching frequency to minimize the noise in the

final application and a constant voltage ripple at fixed VIN. The regulator in steady loading

condition never skip pulses and it operates in continuous conduction mode (CCM) over the

different loading conditions.

Figure 13. Low noise mode operation

Typical applications for the LNM operation are car audio and sensors.

5.5.2

Low consumption mode (LCM)

The low consumption mode maximizes the efficiency at light-load. The regulator prevents

the switching activity whenever the switch peak current request is lower than the ISKIP

threshold. As a consequence the A6986F device works in bursts and it minimizes the

quiescent current request in the meantime between the switching operation.

In LCM operation, the pin SYNCH/ISKIP level dynamically defines the ISKIP current

threshold (see Table 5 on page 8) as shown in Table 11.

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