mic7201 Micrel Semiconductor, mic7201 Datasheet - Page 6

• Manufacturer Part Number: mic7201
• Description: Mic7201 Gainblock? Difference Amplifier
• Manufacturer: Micrel Semiconductor

MIC7201
Applications Information
Input Common Mode Voltage
The MIC7201 tolerates overdriving the inputs by at least
300mV beyond either rail without producing phase inversion.
If the absolute maximum input voltage is exceeded, the input
current should be limited to 5mA to prevent reducing reliabil-
ity. A 10k series input resistor, used as a current limiter will
protect the input structure from voltages as large as 50V
above the supply or below ground.
Output Voltage Swing
Output resistance of the MIC7201 is symmetric; sink and
source output resistances are equal. Output voltage swing is
determined by the load and, given the approximate output
resistance, which may be readily calculated with the following
formula:
V
stage. V
(output swing) portion of the appropriate Electrical Character-
istics table. I
minus V+/2 and divided by R
Electrical Characteristics DC (5V) table, the typical output
voltage drop using a 2k load (connected to V+/2) is 0.015V,
which produces an I
Then:
Driving Capacitive Loads
Driving a capacitive load introduces phase-lag into the output
signal, and this in turn reduces system phase margin. The
application that is least forgiving of reduced phase margin is
a unity gain amplifier. The MIC7201 typically can drive a
500pF capacitive load connected directly to its output.
MIC7201
DROP
Digital
Input
R
R
OUT
OUT
is the voltage dropped within the amplifier output
DROP
LOAD
DAC
1.243mA
V
and I
I
LOAD
DROP
15mV
is equal to the typical output high voltage
Figure 1. Audio DAC
I
I
OUT
OUT
LOAD
LOAD
0.1µF
0.1µF
of (2.5V – 0.015V) / 2k
can be determined from the V
12 1
.
MIC7201
V
LOAD
SUPPLY
1
4.7µF
2
. For example, using the
0.1µF
0.1µF
R
L
1.243mA.
V
OUT
OUT
6
0.1µF
V
0.1µF
IN
V
V
IN+
IN–
V+
2
V
IN
IN+
IN–
IN
3
4
Figure 5. Virtual Ground Generator
3
4
IN+
IN–
MIC7201
IN+
IN–
MIC7201
3
4
3
4
Figure 4. Inverting Unity Gain
50k
50k
MIC7201
MIC7201
50k
50k
Figure 3. Voltage Follower
Figure 2. Gain of One-Half
50k
50k
50k
50k
100k
100k
100k
100k
100k
100k
100k
100k
V–
V+
V–
V+
V
V
V+
V–
V+
V–
2
5
V+
V+
2
5
V
50k
V
50k
V+
V+
2
5
2
5
50k
50k
OUT
1
OUT
1
OUT
1
OUT
1
December 1998
V
V
V
V
OUT
OUT
OUT
OUT
= V
= –V
V
IN
2
IN
V
IN
2
V+
Micrel