ADP1048 Analog Devices, ADP1048 Datasheet - Page 21

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

Data Sheet
AC Line Value Detection
To operate, the controller must detect the ac line value. At
startup, the controller waits for the PSON signal (hardware
PSON, software PSON, or both, depending on how the part
is programmed).
When the PSON signal is present, the controller looks for the
ac line period and value (see Figure 18).
The start-up value for the ac line used by the controller to
initiate the start-up procedure is stored in the VIN_ON register
(Register 0x35). This value is the minimum rms value of the ac
line required for the system to start up. The controller measures
the value of VAC at every half line cycle and compares it with
VIN_ON. If VAC is larger than the value in the VIN_ON register,
the soft start procedure is initiated and the BROWN_OUT flag
is reset.
AC Line Early Fault Detection
After the VIN_ON limit is crossed and the system starts up, the
controller constantly monitors the condition of the ac line (see
Figure 19).
BROWN_OUT FLAG
(REG 0xFE80[2])
VAC
Figure 18. VAC Detection for Startup
VIN_ON (REG 0x35)
ADC INPUT RANGE = 1.6V
HIGH LINE LIMIT (VAC
LOW LINE LIMIT (VAC
VIN_OV_FAULT_LIMIT = 270V
VIN_UV_FAULT_LIMIT = 70V
VIN_UV_WARN_LIMIT = 80V
VIN_OFF = 70V
VIN_ON = 85V
Figure 20. Input Voltage Limits
TH
TH
AC
AC
) = 150V (REG 0xFE36)
) = 180V (REG 0xFE35)
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(REG 0x35)
(REG 0x36)
AC
AC
AC
(REG 0x58)
(REG 0x59)
(REG 0x55)
VIN_LOW FLAG
To provide early detection of ac line faults, the instantaneous
value of VAC is compared to the VIN_OFF value in Register
0x36. If VAC remains below the VIN_OFF threshold for a time
longer than the programmed period, the VIN_LOW flag is set
in Register 0x7C. The programmed period can be either a frac-
tion of the detected ac line period (one-quarter or one-half) or
it can be an absolute time (2 ms or 4 ms); the value is set in
Register 0xFE2E.
The controller does not take any action, but the VIN_LOW
signal can be used to set the AC_OK signal and to trigger
immediate actions in the power system.
The VIN_OFF threshold is intended solely to provide early
warning of problems on the ac line; it is not used to shut down
the power supply. The VIN_UV_FAULT_LIMIT register
(Register 0x59) is used for that purpose.
(REG 0x7C[3])
VAC
VAC
VAC
MAX
MIN
Figure 19. AC Line Early Fault Detection
= 90V
= 265V
HYSTERESIS
AC
AC
ZONE
TIMER
1/4
ADP1047/ADP1048
TIMER
1/4
VIN_OFF (REG 0x36)