ZLDO285 Ver la hoja de datos (PDF) - Diodes Incorporated.
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ZLDO285 Datasheet PDF : 9 Pages
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ZLDO285
APPLICATIONS
3). Low Battery Flag
The ZLDO285 provides an output called Low
Battery Flag (LBF). Unlike many regulators that
only signal that they are falling out of regulation,
the LBF output of the ZLDO285 indicates that the
voltage drop across the regulator has fallen to
less than typically 300mV and so supply failure is
imminent.
4). Over Temperature Shutdown
The ZLDO285 regulator includes an over
temperature shutdown circuit that disables the
regulator if its chip temperature should exceed
125°C for any reason. Although intended to
provide a limited guard against excessive internal
power dissipation, this circuit will shut down the
regulator if its ambient rises above 125°C.
4.8V
ZLDO285
LBF Spg
SC Gnd
Vin D/C
N/C Vout
C3
100nF
C1
10pF
+2.85V
R1
100k
C2
1µF
Microproc.
System
Interrupt
Input
0V
Figure 3
This improved warning gives both more time for
the system supplied to shutdown gracefully and
maintains regulation while this happens. This
could be a vital point if measurements are under
way and must be completed accurately for
instance. The LBF output is driven by an open
collector NPN transistor which pulls low when
the supply to the regulator is failing. Figure 3
shows this output being used. Note that resistor
R1 is necessary only if the interrupt logic does not
include a pull-up resistor.
Thus, the regulator could be used to disable a
circuit in the event of the ambient temperature
within which the circuit is mounted becoming
too high. Any internal power dissipation caused
as a result of supplying load current, will reduce
the ambient temperature at which shutdown
occurs. Note that to achieve the extremely low
dropout voltage and high current performance
provided by the ZLDO devices, the parts can be
damaged by sustained output shorts or
excessive loads when combined with high input
supply voltages. To ensure reliable operation,
keep loads within the SOA graph boundaries
indicated in the typical characteristics.
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