CS1501-FSZ Cirrus Logic Inc, CS1501-FSZ Datasheet - Page 12

• Manufacturer Part Number: CS1501-FSZ
• Description: IC PFC CONTROLLER DCM OCP
• Manufacturer: Cirrus Logic Inc

Specifications of CS1501-FSZ

• Uvlo: 2.1V
• Supply Voltage Range: 8V To 17V
• Startup Current: 68µA
• Operating Supply Current: 1.5mA
• Digital Ic Case Style: SOIC
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +125°C
• Supply Voltage Max: 17V
• Package / Case: 8-SOIC

Thresholds
5.8 Brownout Protection
The CS1501 brownout detection circuit monitors the peak of
the V
it drops below a pre-determined threshold. Hysteresis and
minimum detection time are provided to avoid brownout
detection during short input transients. When brownout is
detected, the CS1501 enters standby mode. On recovery from
brownout, it re-enters normal operating mode.
Current I
V
The digitized current applied to the IAC pin is monitored by the
brownout protection algorithm. When V
brownout detection threshold, the CS1501 triggers a timer.
The IC asserts the brownout protection and stops the
gate-drive switching only if the timer exceeds 56ms. This is
the equivalent of 7 rectified line cycles at 60Hz.
During the brownout state, the device continues monitoring
the input line voltage. The device exits the brownout state
when I
56ms. Typical values for the lower (I
(I
respectively.
The overpower protection may activate prior to brownout
protection, depending on the load.
The maximum response time of the brownout protection
feature occurs at light-load conditions. It is calculated by
Equation 7.
where:
V
12
Brownout
rect
BP(upper)
T
BP(th)
Upper
Lower
Brownout
= R
rect
AC
AC
IAC
input voltage and disables the PWM switching when
Brownout threshold voltage, V
) brownout thresholds are 31.6A and 39.6A,
exceeds the brownout upper threshold for at least
is proportional to the AC input voltage V
xI
=
=
Figure 21. Brownout Sequence
AC
8 ms
8
and R
+
8
-- - 128 94.8
5

+
8 ms
----------- - 128 V V
IAC
5 V
Enter Standby
T
–
Brownout
= R1+R2 in

56 ms
Timer
Start
Start Timer

+
–
56
BP th
BP(th) =
=
Figure 18 on page
BP(lower)

rect
117ms


56 ms
drops below the
+
I
BP(lower)
56 ms
) and upper
Exit Standby
rect
, where
xR
[Eq.7]
IAC
11.
5.9
The overvoltage protection (OVP) will trigger immediately and
stop the gate drive when the current into the IFB pin (I
exceeds 105% of the reference current (I
resumes gate drive switching when the measured current at IFB
drops below I
OVP threshold.
5.10
To limit boost inductor current through the FET and to prevent
boost inductor saturation conditions, the CS1501 incorporates
a cycle-by-cycle peak inductor current limit circuit using an
external shunt resistor to ‘sense’ the FET source current
accurately. The overcurrent protection (OCP) circuit is
designed to monitor the current when the active switch is
turned on. The OCP circuit is enabled after the leading-edge
blanking time (t
reference
overcurrent condition exists. The OCP circuit triggers
immediately, allowing the OCP algorithm to turn off the gate
driver.
The overcurrent protection circuit is also designed to monitor
for a catastrophic overcurrent occurrence by sensing sudden
and abnormal operating currents. A second OCP threshold,
V
exists. This immediately turns off the gate drive and the
system enters a restart mode. The CS1501 inhibits all
switching operations for approximately 1.6ms then attempts to
restart normal operation.
5.11
The CS1501 incorporates an internal Overpower Protection
(OPP) algorithm. This provides protection from overload
conditions. This algorithm uses the condition that output
power is a function of the boost inductor (Section 5.4).
Under moderate overload, V
maintaining rated power and PFC. Further increasing the load
current causes V
(~360V). Below this threshold, the circuit changes its
operating mode to startup with more power available to raise
V
canceled and power is now limited to the rated value. If the
overload is still present, this cycle will repeat.
If a sustained overload, or a repeated cycle of overload events
is detected for greater than 112 mS, the CS1501 shuts down
for 2.5 seconds, then attempts to restart.
cs(clamp)
link
. As V
Overvoltage Protection
Overcurrent Protection
Overpower Protection
, determines whether a severe overcurrent condition
link
voltage,
OVP
reaches its nominal value, startup mode is
LEB
V
– I
OVP
link
OVP(Hy)
). The shunt voltage is compared to a
V
to drop below the startup threshold
=
cs(th)
R
. Equation 8 is used to calculate the
IFB
,
link

to
may droop up to 10% while
I
OVP
determine
+
V
DD
ref
) value. The IC
whether
DS927PP6
[Eq.8]
OVP
an
)