PFS7323-7329
Normal Range for
‘Efficiency Mode’
R = 49.9 kΩ
Normal Range for
‘Full Mode’
R = 24.9 kΩ
I
V
< ~48
µA
IC-OFF
25
μA
20
μA
30
μA
IC-OFF
50
μA
40
μA
IC-OFF
60
μA
PI-6701-030212
I
OCP
I
V
> ~59
µA
V
IN
~140 VAC
~170 VAC
PI-6863-050313
Figure 12. REFERENCE Pin Current Operating Range.
D. Once the start-up sequence check has passed and the
converter goes into soft-start and if PGT is shorted to
SIGNAL GROUND pin, then the PG signal will toggle to the
low state (internal MOSFET is ‘on’) when the output voltage
reaches 85-100% of the set regulation threshold and will
remain in this state until the output voltage reaches zero volt
or conditions in A, B or C occur.
E. Once the start-up sequence check has passed and the
converter goes into soft-start and if PGT is open, then the
PG signal will remain in the high-impedance state (internal
MOSFET is ‘off’).
Reference and Selectable Power Limit
Besides the internal current reference source, the precision
resistor on the REFERENCE pin also allows user selection
between ‘full’ and ‘efficiency’ power limit for each device. The
efficiency power mode will permit user selection of a larger
device for a given output power requirement for increased
conversion efficiency.
In ‘full’ power mode the REFERENCE pin resistor is 24.9 kW
±1%
and the ‘Efficiency’ power limit mode is selected with a
49.9 kW
±1%
resistor.
If the REFERENCE pin is shorted (to GROUND pin) or open
circuited the IC will initiate a fast soft-shutdown and disable the
power MOSFET and remain disabled until all the conditions for
the start-up sequence are satisfied.
The REFERENCE pin resistor value and power mode is latched
at start-up.
Protection Modes
VOLTAGE MONITOR (V) Pin Shutdown
The VOLTAGE MONITOR pin features a shutdown protection
mode which can be used with the VOLTAGE MONITOR pin
resistor or external circuitry to cover system faults. During
start-up (1 V < VFB < 5.8 V) in the event the current through the
VOLTAGE MONITOR pin exceeds the I
V(OFF)
threshold for a
duration exceeding approximately (1
ms),
the IC disables the
internal MOSFET for the entire duration that the VOLTAGE
MONITOR pin current is above I
V(OFF)
. In normal operation, if the
current through the VOLTAGE MONITOR pin exceeds the I
V(OFF)
threshold for a duration exceeding t
V(OFF)
, the IC will re-initiate the
start-up sequence.
Figure 13. Line Dependent OCP.
Brown-In Protection (I
UV+
)
The VOLTAGE MONITOR pin features an input line undervoltage
detection to limit the minimum start-up voltage detected
through the VOLTAGE MONITOR pin. This detection threshold
will inhibit the device from starting at very low input AC voltage.
Brown-Out Protection (I
UV-
)
The VOLTAGE MONITOR pin features a brown-out protection
mode wherein the HiperPFS will turn-off when the VOLTAGE
MONITOR pin current is below the Line UV- threshold (I
UV-
) for a
period exceeding the t
BROWN-OUT
time period. In the event a
single half-line cycle is missing (normal operating line frequency
is 47 to 63 Hz) the brown-out protection will not be activated.
The HiperPFS-2 soft-shutdown in effect gradually reduces the
internal error-voltage to zero volts at rate of 1 V/ms to decay the
power MOSFET on-time to zero.
At peak power (V
E
~5 V) the shutdown time will be approximately
5 ms. The internal error-voltage is held at 0 V for as long as the
input peak voltage is below the brown-in (I
UV+
) threshold. The
internal error-voltage controlled slew to 0 V gradually reduces
the switch on-time to zero to deplete energy stored in the boost
choke as well as input EMI filter for power-down. Once the
error-voltage reaches zero volts the controller is effectively in an
off-state (gated by 5 ms timer) and will restart once all the
conditions of soft-start are satisfied.
At start-up and during soft-start the brown-out threshold (same
as Line UV-) is reduced to I
UV(SS)
and brown-out timer is also
extended to t
UV(SS)
(soft-start brown-out timer).
Soft-start brown-out threshold (I
UV(SS)
) is reset to I
UV-
once the
internal error-voltage has begun to fall (indicating the converter
has reached steady-state output voltage regulation).
The soft-start brown-out timer is reset to the normal brown-out
timer once the internal error-voltage has begun to fall (indicating
the converter has reached steady-state output voltage regulation)
and the VOLTAGE MONITOR pin current exceeds I
UV-
.
If the VOLTAGE MONITOR pin current is still below the I
UV(SS)
threshold after the end of the soft-start brown-out timer (t
UV(SS)
),
then the converter will fail to start and initiate a soft-shutdown
followed by a soft start-up sequence as described in flowchart
in Figure 8.
9
www.powerint.com
Rev. B 06/13
POWERINT [ POWER INTEGRATIONS, INC. ]
