AN4163 datasheet(22/33 Pages) STMICROELECTRONICS

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Test results and significant waveforms

AN4163

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DocID023658 Rev 2

case of light load and to minimize the no-load input consumption. Should the residual

consumption of the chip be an issue, it is also possible to cut down the supply voltage.

Interface circuits like those are shown in Figure 41. Needless to say, this operation assumes

that the cascaded DC-DC converter stage works as the master and the PFC stage as the

slave or, in other words, that the DC-DC stage starts first, it powers both controllers and

enables/disables the operation of the PFC stage.

Figure 41. Interface circuits that let DC-DC converter’s controller IC disable the L4984D

Table 1 summarizes all the operating conditions that cause the device to stop working.

AM13426v1

L4984D

L6591

L6699

PFC_STOP

PFC_OK

Table 1. Summary of L4984D idle states

Condition

Caused or revealed by

IC behavior

Restart condition

Typical IC

consumption

activation

UVLO

Vcc < VccOff

Disabled

Vcc > VccOn

65 µA

Yes

Standby

VPFC_OK < VPFC_OK_D

Stop switching

VPFC_OK > VPFC_OK_E

2.2 mA

AC brownout

VVFF < VDIS

Stop switching

VVFF > VEN

1.5 mA

Yes

OVP

VPFC_OK > VPFC_OK_S

Stop switching VPFC_OK < VPFC_OK_R

2.2 mA

Feedback

failure

VPFC_OK > VPFC_OK_S

and

VINV < 1.66 V

Latched-off

Vcc < Vccrestart

then

Vcc > VccOn

180 µA

Yes

Low

consumption

VCOMP < 2.4V

Burst mode

VCOMP > 2.4V

2.2 mA

Saturated

boost inductor

Vcs > VCS_th

Stop switching

Auto restart after 300 s

4 mA

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