ADP1047ARQZ-R7 datasheet(20/84 Pages) AD

20 / 84 page

ADP1047/ADP1048

Data Sheet

Rev. 0 | Page 20 of 84

LINE FAULT PROTECTIONS AND SOFT START SEQUENCING

PSON OPERATION

To comply with PMBus standards, the PFC circuit controlled

by the ADP1047/ADP1048 can be turned on and off 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 ADP1047/ADP1048 are capable of detecting several

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.

•

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)

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.

VAC AVERAGE

(REG 0xFE26)

VAC

THRESHOLD

(REG 0xFE25)

HALF AC

LINE PERIOD

Figure 17. AC Line Period Detection

ADP1047ARQZ-R7 数据表(PDF) 20 Page - Analog Devices

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