NCP1200AD100R2 ON Semiconductor, NCP1200AD100R2 Datasheet - Page 11

• Manufacturer Part Number: NCP1200AD100R2
• Description: IC CTRLR PWM CM HV 8SOIC
• Manufacturer: ON Semiconductor

Specifications of NCP1200AD100R2

• Output Isolation: Isolated
• Frequency Range: 90 ~ 114kHz
• Voltage - Input: 12.1 ~ 16 V
• Operating Temperature: 0°C ~ 150°C
• Package / Case: 8-SOIC (0.154", 3.90mm Width)
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Other names: NCP1200AD100ROSTR

a new startup phase by turning the current source on: V
rises toward 12 V and again delivers output pulses at the
UVLO
removed before UVLO
its normal operation. Otherwise, a new fault cycle takes
place. Figure 21 shows the evolution of the signals in
presence of a fault.
Calculating the V
depends upon the V
V
on the startup sequence of your system, i.e. when you first
apply the power to the IC. The corresponding transient fault
duration due to the output capacitor charging must be less
than the time needed to discharge from 12 V to 10 V,
otherwise the supply will not properly start. The test consists
CC
When this level crosses 5.4 V typical, the controller enters
As the above section describes, the fall down sequence
line to go from 12 V to 10 V? The required time depends
Figure 21. If the fault is relaxed during the V
If the fault still persists when V
H
crossing point. If the fault condition has been
CC
CC
Capacitor
L
level: how long does it take for the
FAULT FLAG
approaches, then the IC continues
5.4 V
12 V
10 V
INTERNAL
V
Drv
CC
STARTUP PHASE
CC
reached UVLO
REGULATION
PULSES
DRIVER
OCCURS
HERE
http://onsemi.com
CC
natural fall down sequence, the IC automatically resumes.
CC
L
LATCHOFF
, then the controller cuts everything off until recovery.
FAULT OCCURS HERE
PHASE
11
in either simulating or measuring in the lab how much time
the system takes to reach the regulation at full load. Let’s
suppose that this time corresponds to 6 ms. Therefore a V
fall 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:
DV = 2 V. Then for a wanted Dt of 10 ms, C equals 9 mF or
22 mF for a standard value. When an overload condition
occurs, the IC blocks its internal circuitry and its
consumption drops to 350 mA typical. This happens at
V
are in latchoff phase. Again, using the calculated 22 mF and
350 mA current consumption, this latchoff phase lasts:
296 ms.
CC
= 10 V and it remains stuck until V
FAULT IS
RELAXED
PULSES
DRIVER
TIME
TIME
TIME
CC
Dt + DV @ C
reaches 5.4 V: we
i
, with
CC