NCP1379
ELECTRICAL CHARACTERISTICS (Unless otherwise noted: For typical values TJ = 25°C, VCC = 12 V, VZCD = 0 V, VFB = 3 V,
VCS = 0 V, Vfault = 1.5 V, CT = 680 pF) For min/max values TJ = −40°C to +125°C, Max TJ = 150°C, VCC = 12 V)
Symbol
Parameter
Conditions
Min Typ Max Unit
FEEDBACK SECTION − FEEDBACK
VH2D
VH3D
VH4D
VHVCOD
VHVCOI
VH4I
VH3I
VH2I
Valley threshold
FB voltage where 1st valley ends and 2nd valley
starts
FB voltage where 2nd valley ends and 3rd valley
starts
FB voltage where 3rd valley ends and 4th valley
starts
FB voltage where 4th valley ends and VCO starts
FB voltage where VCO ends and 4th valley starts
FB voltage where 4th valley ends and 3rd valley
starts
FB voltage where 3rd valley ends and 2nd valley
starts
FB voltage where 2nd valley ends and 1st valley
starts
VFB decreases
VFB decreases
VFB decreases
VFB decreases
VFB increases
VFB increases
VFB increases
VFB increases
V
1.316 1.4 1.484
1.128 1.2 1.272
0.846 0.9 0.954
0.732 0.8 0.828
1.316 1.4 1.484
1.504 1.6 1.696
1.692 1.8 1.908
1.880 2.0 2.120
PROTECTIONS − FAULT PROTECTION
TSHDN
Thermal Shutdown
Device switching (FSW
140
−
170 °C
around 65 kHz)
TSHDN(HYS) Thermal Shutdown Hysteresis
−
40
−
°C
tOVLD
Overload Timer
VFB = 4 V, VCS > VILIM
75
85
95
ms
tOVLD(off)
OFF phase in auto−recovery fault mode
1.0
1.2
1.4
s
tSSTART
Soft−start duration
VFB = 4 V, VCS ramping
2.8
3.8
4.8 ms
up, measured from 1st
DRV pulse to VCS(peak) =
90% of VILIM
VBO
Brown−Out level
VFault decreasing
0.744 0.800 0.856 V
IBO
Sourced hysteresis current VFault > VBO
VFault = VBO + 0.2 V
9
10
11
mA
tBO(delay)
Delay before entering and exiting Brown−out
22.5 30.0 37.5 ms
VOVP
Internal Fault detection level for OVP
VFault increasing
2.35 2.5 2.65 V
tlatch(delay) Delay before latch confirmation (OVP)
22.5
30
37.5 ms
VFault(clamp) Clamped voltage (Fault pin left open)
Fault pin open
1.0
1.2
1.4
V
RFault(clamp) Clamping resistor (Note 3)
1.30 1.55 1.80 kW
3. Guaranteed by design
4. The peak current setpoint goes down as the load decreases. It is frozen below Ipeak(VCO) (Ipeak = cst)
5. If negative voltage in excess to −300 mV is applied to ZCD pin, the current setpoint decrease is no longer guaranteed to be linear
6. Minimum value for TJ = 125°C
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