NCP1201P60 ON Semiconductor, NCP1201P60 Datasheet - Page 15

• Manufacturer Part Number: NCP1201P60
• Description: IC CTRLR PWM CM OTP 8DIP
• Manufacturer: ON Semiconductor
• Type: PWM Current-Mode Controller For Universal Off-Line Suppliesr

Specifications of NCP1201P60

• Output Isolation: Isolated
• Frequency Range: 52 ~ 72kHz
• Voltage - Input: 12.5 ~ 16 V
• Voltage - Output: 500V
• Operating Temperature: -40°C ~ 150°C
• Package / Case: 8-DIP (0.300", 7.62mm)
• Input Voltage Range: - 0.3 V to 16 V
• Mounting Style: Through Hole
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: NCP1201P60OS

10 V after startup phase. When powering the device from an
auxiliary winding, meeting this condition can sometimes be
problematic since upon startup, V
not down as with a DSS. As a result, V
and the fault logic is not activated. If a short- -circuit takes
place, the fault circuitry activates as soon as V
below 10 V (because of the coupling between V
Calculating the V
depends upon the V
V
time depends on the powerup sequence of your system, i.e.
when you first apply the power to the device. The
corresponding transient fault duration due to the output
capacitor charging must be less than the time needed to
discharge from 12.5 V to 10.5 V, otherwise the supply will
not properly startup. The test consists in either simulating or
measuring in the laboratory to determine time required for
the system to reach the regulation at full load. Let’s assume
CC
As shown below, the fault logic is armed once V
As the above section describes, the fall down sequence
line to decrease from 12.5 V to 10.5 V. The required
CC
CC
level, i.e. how long does it take for the
Capacitor
12 V
10 V
V
Drv
FB
CC
CC
CC
naturally goes up and
Figure 34. Fault Protection Timing Diagram
never crosses 10 V
occurs here
Regulation
Open--loop
FB level
Overload is
not activated
CC
Pulses
CC
Regulation
Driver
collapses
aux
crosses
http://onsemi.com
and
Overload is
activated
15
Fault occurs here
V
is open, V
avoid this problem, the application note “Tips and Tricks
with NCP1200, AN8069/D” offers some possible solutions
where the DSS is kept for protection logic operation only but
all the driving power is derived from the auxiliary winding.
Some solutions even offer the ability to disable the DSS in
standby and benefit to low standby power.
that this time corresponds to 6.0 ms. Therefore a V
time of 10 ms could be well appropriated in order to not
trigger the overload detection circuitry. If the corresponding
IC consumption, including the MOSFET drive, establishes
at 1.8 mA for instance, we can calculate the required
capacitor using the following formula:
ΔV = 2.0 V. Then for a wanted Δt of 10 ms, C equals 9.0 mF
or 10 mF for a standard value. When an overload condition
occurs, the IC blocks its internal circuitry and its
consumption drops to 575 mA typical. This explains the V
falling slope changes after latchoff in Figure 34.
out
Latched--off
), but in presence of a broken optocoupler, i.e. feedback
CC
No synchronization
between DSS and
fault event
increases and the fault will never triggered! To
Time
Time
Time
Δt = ΔV × C
i
CC
, with
fall
CC