ADP1048 Analog Devices, ADP1048 Datasheet - Page 20

• Manufacturer Part Number: ADP1048
• Description: Digital Power Factor Correction Controller with accurate AC Power Metering
• Manufacturer: Analog Devices

ADP1047/ADP1048
LINE FAULT PROTECTIONS AND SOFT START SEQUENCING
PSON OPERATION
To comply with PMBus standards, the PFC circuit controlled
by the
hardware PSON pin and/or the software PSON command. The
setting of Bit 2 in Register 0x02 determines whether the PSON
pin and/or the PSON command is used. If the PSON pin is used,
the pin can be configured to be either active high or active low
(see Table 18).
AC LINE DETECTION
The
parameters of the ac line input voltage and taking the appro-
priate programmed actions when necessary. The detection is
a combination of time and voltage measurements and is
implemented via the VAC pin, which detects the rectified ac
input voltage. This allows early detection of ac line faults and
early warning for the host system, thereby increasing reliability.
Five main parameters are related to ac line detection.
•
•
•
•
•
(REG 0xFE25)
THRESHOLD
ADP1047/ADP1048
VAC_LINE_PERIOD (Register 0xFE85)
VAC_THRESHOLD_SET (Register 0xFE25)
VAC_THRESHOLD_READ (Register 0xFE26)
MIN_AC_PERIOD_SET (Register 0xFE27)
MAX_AC_PERIOD_SET (Register 0xFE28)
ADP1047/ADP1048
VAC
are capable of detecting several
can be turned on and off by the
Figure 17. AC Line Period Detection
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A
LINE PERIOD
AC Line Period and Zero Crossing
The input ac line period is measured every half period of the ac
line cycle and is reported in the VAC_LINE_PERIOD register
(Register 0xFE85).
During the first 40 ms, the ac line period is measured between
two consecutive falling crossings of the threshold value, which
is set in the VAC_THRESHOLD_SET register (Register 0xFE25,
Bits[6:0]). The ac line period is then measured between two
consecutive falling crossings and compared to the average value
of the input line voltage, which is calculated during each half line
period. The VAC average reading can be found in the VAC_
THRESHOLD_READ register (Register 0xFE26, Bits[6:0]).
If the measured period is larger than MAX_AC_PERIOD_SET
or smaller than MIN_AC_PERIOD_SET, the default, MAX_AC_
PERIOD_SET, is used as the value of the period.
As shown in Figure 17, the two consecutive crossing points,
B and C, are used to determine the zero-crossing point of the
ac line. The middle point between B and C is calculated as the
zero-crossing point.
This information is used by the control loop, as well as the
power metering block.
HALF AC
B
C
Data Sheet
VAC AVERAGE
(REG 0xFE26)