ZXCL200 View Datasheet(PDF) - Zetex => Diodes
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Description
Manufacturer
ZXCL200 Datasheet PDF : 9 Pages
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ZXCL200
Input to Output Diode
In common with many other regulators, the ZXCL200
device has an inherent diode associated with the
output series pass transistor. This diode has its anode
connected to the output and its cathode to the input.
The internal diode is normally reverse biased, but will
conduct if the output is forced above the input by more
than a VBE (approximately 0.6V). Current will then flow
from Vout to Vin. For safe operation, the maximum
current in this diode should be limited to 5mA
continuous and 30mA peak. An external schottky diode
may be used to provide protection when this condition
cannot be satisfied.
Increased Output current
Any ZXCL series device may be used in conjunction
with an external PNP transistor to boost the output
current capability. In the application circuit shown
below, a FMMT717 device is employed as the external
pass element. This SOT23 device can supply up to 2.5A
maximum current subject to the thermal dissipation
limits of the package (625mW). Alternative devices
may be used to supply higher levels of current. Note
that with this arrangement, the dropout voltage will be
increased by the VBE drop of the external device. Also,
care should be taken to protect the pass transistor in
the event of excessive output current.
VIN
Q1
FMMT717
R1
5.6R
C3
1uF
C2
1uF
U1
ZXCL SERIES
VIN
VO
EN
VOUT
C1
1uF
Scheme to boost output current to 2A
ISSUE 1 - SEPTEMBER 2001
6
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