L9444 查看數據表（PDF） - STMicroelectronics
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L9444 Datasheet PDF : 5 Pages
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L9444VB -L9448VB - L9480VB
ABSOLUTE MAXIMUM RATINGS
Symbol
VS
Iclamp
Iout
Tj , Tstg
Parameter
Transient Overvoltage :
Load Dump : 5ms ≤ Trise ≤ 10ms,
τf Fall Time Constant ≤ 100ms, Rsource ≥ 0.5Ω
Current into Low Energy Clamping Zener
(Trise = 5µs ; Tdecay ≤ 2ms ; duty cycle ≤ 5%)
Maximum Output Current
Junction and Storage Temperature Range
THERMAL DATA
Symbol
Rth i-case
Parameter
Thermal Resistance Junction-case
PIN CONNECTION (top view)
Value
Unit
80
V
100
mA
5.5
A
– 55 to + 150
°C
Max.
Value
3
Unit
°C/W
DEVICE OPERATION
The alternator voltage, rectified by the auxiliary di-
ode trio, is compared with an external reference
and the resulting signal switches the output stage,
driving the alternator field coil.
As the regulator is a self-oscillating type, the
switching frequency depends on the whole sys-
tem parameter set (including the alternator char-
acteristics).
The regulator has an integrated filter in the volt-
age sensing path. Consequently it doesn’t need -
in the standard application- any external compo-
nent.
Anyway an external capacitor (0.1 - 1µF) must be
inserted between VS and Ground guaranteeing
the correct behaviour of the device when the rec-
tifying diodes feature very high switching spikes
that are not filtered by the devices.
This external capacitor must also be used when
the impedances of the cables connecting the al-
2/5
ternator to the battery are so high to cause a su-
perimposed ripple on the alternator voltage higher
than 3-4V.
The devices regulation voltage and the tempera-
ture coefficient may be independently set by
suited metal mask selections ; furthermore the
regulation voltage is trimmed within ± 1% of the
nominal value @ 25°C.
The devices have an unique -and patented- sys-
tem to compensate the self-heating of the die due
to the power dissipated in the output stage. In this
way the internal reference voltage tracks the case
temperature rather than the die one.
The device can withstand the reverse battery and
the load dump (up to 80V) ; They can absorb, into
the internal clamping zeners, low energy spikes
up to a level of 100mA and its output is short cir-
cuit protected.
Finally the internal thermal shutdown avoids any
possible device damage due to overtemperature
problems.
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