ZXCT1032 查看數據表（PDF） - Zetex => Diodes
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ZXCT1032 Datasheet PDF : 10 Pages
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ZXCT1032
2 The output voltage also increases due to the load current powering up the load and charging
any capacitance. After the initial soft start (load current stabilizing) the timing capacitor
charges up to 4V and the device enters its normal mode of operation. The external MOSFET
will be now fully enhanced minimizing any serial voltage drop.
20
18
16
14
12
10
8
6
4
2
0
0
VLOAD
ZXCT1032 Normal Operation
1
0.8
ILOAD
VISET
VCT
10*VSENSE
5
10
Time ms
VIN+ = 18V
0.6
RSENSE = 0.2Ω
CT = 220nF
VISET = 2.1V
0.4
Trip current = 1A
0.2
0
15
20
The ZXCT1032 has now entered its over-current detector mode; it is effectively “transparent”
to the load until the current monitor output exceeds the trip point.
3 Fuse operation is provided by the trip comparator whose threshold voltage is set by VISET
(internally nominally 2.1V, although this threshold can easily be overdriven). As the load
current increases, so does the monitor voltage. When the current monitor output voltage
exceeds VISET, the trip comparator output goes high and sets the latch with the following
results:
a The output drive is disabled.
b The open collector Flag output goes low to indicate a fault condition.
c The 200A current source is turned off and CT starts to discharge slowly via a 3.3A current
source.
ZXCT1032 Timing in over-current condition
2.5
2.5
VISET
2
2
VIN+
= 18 V
RSENSE = 0.2 ?
1.5
ILOAD
>1A
1.5
VCT
CT
= 220 nF
VISET = 2.1 V
Trip current = 1 A
1
1
0.5
ILOAD
0
0
50
100
Time (ms)
0.5
0
150
Issue 3 - April 2007
7
© Zetex Semiconductors plc 2007
www.zetex.com
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