ZLDO300 Просмотр технического описания (PDF) - Zetex => Diodes
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ZLDO300 Datasheet PDF : 9 Pages
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ZLDO300
APPLICATIONS
3). Low Battery Flag
The ZLDO300 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 ZLDO300 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 ZLDO300 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
ZLDO300
LBF Spg
SC Gnd
Vin D/C
N/C Vout
C3
100nF
C1
10pF
+3.0V
R1
100k
C2
1µF
Microproc.
System
Interrupt
Input
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.
0V
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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