IC,ANALOG MUX,TRIPLE,2-CHANNEL,BIPOLAR,TSSOP,24PIN,PLASTIC

AD8186ARUZ

Manufacturer Part NumberAD8186ARUZ
DescriptionIC,ANALOG MUX,TRIPLE,2-CHANNEL,BIPOLAR,TSSOP,24PIN,PLASTIC
ManufacturerAnalog Devices Inc
TypeAnalog Multiplexer
AD8186ARUZ datasheet
 


Specifications of AD8186ARUZ

Rohs CompliantYESFunctionMultiplexer
Circuit3 x 2:1On-state Resistance350 mOhm
Voltage Supply SourceSingle SupplyVoltage - Supply, Single/dual (±)3.5 V ~ 5.5 V
Current - Supply15mAOperating Temperature-40°C ~ 85°C
Mounting TypeSurface MountPackage / Case24-TSSOP (0.173", 4.40mm Width)
Package24TSSOPMultiplexer Architecture2:1
Maximum Turn-off Time17(Typ)@5V nsMaximum Turn-on Time4(Typ)@5V ns
Power Supply TypeSingleLead Free Status / RoHS StatusLead free / RoHS Compliant
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The AD8187
The AD8187 uses on-chip feedback resistors to realize the gain-
of-two function. To provide low crosstalk and a high output
impedance when disabled, each set of 500 Ω feedback resistors is
terminated by a dedicated reference buffer. A reference buffer is
a high speed op amp configured as a unity-gain follower. The
three reference buffers, one for each channel, share a single, high
impedance input, the V
pin (see Figure 4). V
REF
current is typically less than 2 µA.
5V
A0
5V
B0
5V
GBUF 0
V
REF
VF-1
5V
GBUF 1
500
500
VF-2
5V
GBUF 2
500
500
Figure 4. Conceptual Diagram of a Single
Multiplexer Channel, G = +2
This configuration has a few implications for single-supply
operation:
1) On the AD8187, V
may not be tied to the most negative
REF
analog supply, V
.
EE
Limits on Reference Voltage (AD8187, see Figure 5):
+
<
<
V
1 3
.
V
V
V
– .
EE
REF
CC
<
<
1 3
.
V
V
3 4
.
V on
0
V / V Supplies
REF
5V
A0
OUT 0
5V
V
REF
Figure 5. Output Compliance of Main Amplifier
Channel and Ground Buffer
2) Signal at the V
pin appears at each output. Therefore,
REF
V
should be tied to a well bypassed, low impedance source.
REF
Using superposition, it is easily shown that
=
×
V
2
V
V
OUT
IN
REV. A
3) To maximize the output dynamic range, the reference voltage
should be chosen with some care.
For example, consider amplifying a 700 mV video signal with a
sync pulse 300 mV below black level. The user might decide to set
V
at black level to preferentially run video signals on the faster
REF
NPN transistor path. The AD8186 would, in this case, allow a
reference voltage as low as 1.3 V + 300 mV = 1.6 V. If the AD8187
input bias
REF
is used, the sync pulse would be amplified to 600 mV. Therefore,
the lower limit on V
routing RGB video, an advantageous configuration would be to
employ +3 V and –2 V supplies, in which case V
OUT 0
tied to ground.
1
If system considerations prevent running the multiplexer on split
supplies, a false ground reference should be employed. A low
impedance reference may be synthesized with a second opera-
500
tional amplifier. Alternately, a well bypassed resistor divider
VFO
may serve. Refer to the Application section for further explana-
500
tion and more examples.
OUT1
OUT2
Figure 6a. Synthesis of a False Ground Reference
1 6
V
5
5V
1.3V
V
= 3.7V
O_MAX
V
OUT
V
= 1.3V
O_MIN
1.3V
GND
Figure 6b. Alternate Method for Synthesis of a
False Ground Reference
5V
1.6V
High Impedance Disable
V
= 3.4V
O_MAX
Both the AD8186 and the AD8187 may have their outputs
V
REF
disabled to a high impedance state. In the case of the AD8187,
V
= 1.3V
O_MIN
the reference buffers also disable to a state of high output
1.3V
impedance. This feature prevents the feedback network of a
GND
disabled channel from loading the output, which is valuable
when busing together the outputs of several muxes.
REF
–13–
AD8186/AD8187
becomes 1.3 V + 600 mV = 1.9 V. For
REF
REF
5V
10k
100k
0.022 F
100
OP21
1 F
1 F
FROM 1992 ADI AMPLIFIER
APPLICATIONS GUIDE
GND
5V
10k
V
REF
1 F
10k
CAP MUST BE LARGE
ENOUGH TO ABSORB
TRANSIENT CURRENTS
WITH MINIMUM BOUNCE.
could be
V
REF