ncp1234ad100r2g ON Semiconductor, ncp1234ad100r2g Datasheet - Page 28
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ncp1234ad100r2g
Manufacturer Part Number
ncp1234ad100r2g
Description
Ncp1234 Fixed Frequency Current Mode Controller For Flyback Converters
Manufacturer
ON Semiconductor
Datasheet
1.NCP1234AD100R2G.pdf
(33 pages)
and the DRV switching starts only if it is allowed; whereas
the Low latch (typically sensing an overtemperature) is
taken into account only after the soft−start is finished. In
addition, the NTC current is doubled to I
the soft−start period, to speed up the charging of the Latch
pin capacitor. The maximum value of Latch pin capacitor is
given by the following formula (The standard start−up
condition is considered and the NTC current is neglected) :
Temperature Shutdown
a trip point guaranteed above 135°C and below 165°C, and
a typical hysteresis of 30°C. When the temperature rises
above the high threshold, the controller stops switching
Internal Latch Signal
The die includes a temperature shutdown protection with
V
V
CC(min)
CC(on)
V
CC
DRV
latch event)
allowed (no
Switching
pre-start phase
Latch signal
Figure 47. Latch−off Function Timing Diagram
high during
NTC(SSTART)
http://onsemi.com
during
28
instantaneously, and the HV current source is turned off.
Internal logic state is reset. When the temperature falls
below the low threshold, the HV start−up current source is
enabled, and a regular start−up sequence takes place.
C
initiated by
LATCHmax
Start-up
V
CC(on)
(t
Latch
Noise spike
+
+
ignored
t
2.8 @ 10
SSTARTmin
blanking)
−3
V
1.0
clamp0min
@ 130 @ 10
@ I
NTC(SSTART)min
−6
F + 364 nF
Latch-off
time
time
time
(eq. 2)