88EM8010/88EM8011
Datasheet
Figure 19: Internal Block for Zero-cross Detection, Brown-out Protection
88EM8010
Brown-Out
Protection
/8011
Vline _ pk
AC
IN
Predictive
Sinusoidal
AC Voltage
Phase (
)
φ
Ra
Rb
Zero
Crossing
VIN
Peak
detecting
pulse
Rc
Power Limit
Threshold
Selection
To get a proper sinusoidal AC voltage, UVLO, and peak voltage detection, we need to choose the
right value for the sensing resistors: Ra, Rb, and Rc (See Figure 19). If the value is too small there
will be higher power loss and if the value is too big the resistor will not properly work due to the
picking noise of the VIN signal. The recommended values are shown below:
Ra + Rb
100 1.8MΩ
=
=
Rc
1
18kΩ
Equation (1)
For the input voltage resistor divider, the appropriate combination based on the voltage / power
rating of the resistors should also be considered.
Doc. No. MV-S104861-01 Rev. –
Page 28
Copyright © 2009 Marvell
September 30, 2009, 2.00
Document Classification: Proprietary
MARVELL [ MARVELL TECHNOLOGY GROUP LTD. ]
