AD22001N データシートの表示（PDF） - Analog Devices
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AD22001N Datasheet PDF : 8 Pages
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AD22001
INPUTS AND SUPPLY
+VS 2
CHIP
ENABLE
1
GND 20
–IN1 4
RS
+IN1
5
INFUSE 1 & 2 6
–IN2
9
RS
+IN2
8
–IN3
11
RS
+IN3
10
–IN4 14
RS
+IN4
15
–IN5
16
RS
+IN5
17
INFUSE 5 19
SWITCH &
LIMITER
OUTPUTS
POWER SUPPLY
3
OUTPUT
VOUTPS
CHANNEL 1
SIGNAL OUTPUTS
7
OUT 1 & 2
CHANNEL 2
CHANNEL 3
13
12
OUT 3 & 4
OUT (3 × 4)
CHANNEL 4
CHANNEL 5
18
OUT 5
Figure 3. AD22001 Connection Diagram
Thus, in the absence of voltage applied to light the lamp, the
lamp resistance holds the common-mode voltage low, and no
fault is indicated. When the lamp circuit is powered, voltage on
the comparator inputs activates the comparator which indicates
a fault if the lamp current does not cause the shunt voltage to
exceed the threshold.
Cold Lamp Test
In addition to the standard hot lamp test, four of the compara-
tors have a cold lamp test current of about 60 µA applied. If the
lamp circuit is not switched on but the lamp circuit is incom-
plete (failed lamp or connection), the small test current will
raise the common-mode voltage of the comparator at its input
and cause it to indicate a fault. Individual comparator inputs
draw about 10 µA each.
Description of Channel 5
The single comparator in Channel 5 is intended for brake-light
testing. Comparator 5 does not have the cold test feature, since
this lamp is normally tested in conjunction with the brake-light
switch. The comparator is combined with a fuse test circuit
which checks for battery voltage at its input. This input
normally connects between the fuse and brake-light switch.
The outputs of the hot lamp test and the fuse test are combined
at OUT 5 which indicates zero or low as the normal or okay
state and one or high if either test fails. The output will indicate
a fault if battery voltage is lost from the fuse test line, or if the
lamp circuit is powered, but the circuit fails to draw current.
Description of Channels 3 and 4
Comparators 3 and 4 are linked to test pairs of lamp circuits. In
addition to the hot lamp test, Channels 3 and 4 each have a cold
lamp test current. A fault for either test at input 3 or 4 will
cause their common output, OUT 3 & 4, to indicate failure
(registered as a one or high).
These comparators are intended for lamp circuits which are
switched simultaneously, but are fused independently. A special
linkage between the comparators causes them to indicate a fault
if common-mode voltage is applied to only one of the pair. This
functions as a test of both fuses.
One additional output is provided which tests when both lamps
are switched on (whether the lamp circuit draws current or not).
This circuit signals a zero or low level at OUT (3 ϫ 4) whenever
both lamp circuits are powered (implying fuses are present) and
a one or high level otherwise.
Description of Channels 1 and 2
Comparators 1 and 2 are also linked and share a common out-
put. A fault at either input will register as a one or high at OUT
1 & 2. Otherwise this output will be low. Each of these com-
parators also has a cold lamp test current. These comparators
are intended for two lamp circuits which have a common fuse,
and a fuse test line, similar to the brake-light test, is brought
out.
A summary of the tests performed by each channel is given in
Table I.
Signal Outputs
The signal outputs, OUT 1 & 2, OUT 3 & 4, OUT (3 ϫ 4),
and OUT 5, are NPN collectors with pull-up currents provided
by the power control section. These currents are about 75 µA
each, and are intended to be sufficient to drive high level CMOS
inputs.
Table I. Summary of Recommended Applications and
Tests Performed for Each Channel
In a common automotive application, the AD22001 can be used
to monitor the following lamps:
Channel
Recommended
Applications
Tests
Performed
1, 2
Fog Light Front
I, II, III
Fog Light Rear
Number Plate Light
3, 4
Low Beam Headlight I, II, IV
Parking/Position
Taillight
5
Brake Light
I, III
The following tests are performed and status indicated with the
AD22001:
Test Description
I
Hot Lamp Test: Lamp is functional.
Test performed while lamp is switched on.
II
Cold Lamp Test: Lamp is functional.
Test performed while lamp is switched off.
III
Fuse is in place and functional.
IV
The two monitored light bulbs are powered simulta-
neously. This can be used as an implicit fuse test.
–4–
REV. A
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