AS8401 查看數據表（PDF） - austriamicrosystems AG
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AS8401 Datasheet PDF : 11 Pages
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Multipurpose control ASIC for OMNINET – Data Sheet
AS8401
Austria Mikro Systeme International AG
1. Automatic mode recognition / mode switching, which is controlled by detection of the driver
voltage VTR related to the source potential:
• Operating as a low side switch (mode1), the driver voltage is approximately 10V and
the point of switching is approximately 25V.
• When the AS8401 operates as a high side switch, during the transition of the OMNIFET
to conduction, provided that the ASIC’s supply voltage, VTR, remains constant, the
ASIC’s output current should be maintained.
2. A bandgap stabilised 5V voltage regulator, which generates the supply voltage for the
digital control section and all the voltage references
3. A floating ground interface to the controlling processor (pin IN), comprised of a reference
current supply and a general current supply, which implements the following functions:
• Generation of a logic voltage signal from the ground-free input current at the pin IN
• In on-state there are further derived currents for the production of the delay and rise/fall
times of the driver from the input current at the pin IN
• After the OMNIFET has been switched off and an additional time delay, the control
ASIC enters power down mode. During power down the current consumption is 80µA
or less. The time delay is necessary to ensure fast comparator operation in order to
complete the power down sequence.
4. A time-delayed power down circuit for the control of the generation of supply current (see
point 4)
5. Voltage delimitation which limits the voltage between gate and source of the OMNIFET to
13V ±1,0V (Protection of the OMNIFET).
The ASIC controls the OMNIFET between gate and source (in particular also when it is used in
high-side-switch applications). The operating condition in which the source potential is more
positive than the gate potential, not permitted for the OMNIFET, is avoided. The use of the
source potential of the OMNIFET as ASIC ground for the ground free coupling between ASIC
and the processor causes fast variable ASIC ground potential during the switching operation
particularly when the AS8401 is used in high side switch applications.
The size of the switching-on pulses and switching-off pulses and thus the rise and fall times
with given gate-source capacities of the OMNIFET can be programmed by an external resis-
tance RIN, which determines the input current at the pin IN, within certain limits. The switching
time varies approximately in inverse proportion to the current IIN at the pin IN. Thereby it is
possible to adapt the AS8401 to the particular requirements of the OMNIFET (taking into ac-
count gate source capacitance and required delay/transition times) within certain limits (this
adjustment range is not constituent of these Device Specification). This adaptability is limited
by the possible range of the current at the input pin IN.
Rev. A December 1999
Page 4 of 11
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