Figure 12. External Burst-Mode (EBM) function – circuit details

During the external burst-mode condition (FB < VFB_FF/EBM), the system application should guarantee VCC >

VCC_OFF to minimize the power consumption. In fact, in case the VCC pin voltage approaches the device turn-off

threshold the internal HV-startup is turned on to bring VCC voltage to the turn-on threshold VCC_ON.

Figure 13. External Burst-Mode (EBM) function – timing

5.8

Disable operation (DISABLE function)

Forcing the COMP pin lower than the internal threshold VCOMP_DIS (0.7 V typ.), the device stops the operation

and enters into low power consumption. The Error Amplifier is turned off and a weak internal pull-up current

ICOMP_DIS (10 µA typ.) is activated. De-bounce time TCOMP_DIS_DB (50 µs typ.) is provided to avoid false

triggering.

Referring to Figure 14, releasing the external pull-down the internal pull-up current ICOMP_DIS charges the

compensation network connected between COMP pin and ground and the COMP voltage starts to increase.

As soon as the COMP pin reaches the enable threshold VCOMP_EN (0.9V typ.), the device turns on the internal

HV-startup current generator to bring VCC voltage to the turn-on threshold VCC_ON and restarts the operation

implementing the soft-start .

L4985

Disable operation (DISABLE function)

DS13769 - Rev 3

page 16/27