AD588
Data Sheet
+15V
As shown in Figure 40, the AD588 is an excellent choice for the
control element in a bipolar bridge driver scheme. Transistor Q1
and Transistor Q2 serve as series-pass elements to boost the
current drive capability to the 28 mA required by a typical
350 Ω bridge. A differential gain stage can still be required if the
bridge balance is not perfect. Such gain stages can be expensive.
220Ω
Q
=
1
2N3904
7
6
4
3
A3
A4
1
–
+
R
B
E
O
Additional common-mode voltage reduction is realized by
using the circuit illustrated in Figure 41. A1, the ground sense
amplifier, serves the supplies on the bridge to maintain a virtual
ground at one center tap. The voltage that appears on the opposite
center tap is now single-ended (referenced to ground) and can
be amplified by a less expensive circuit.
A1
R1
AD588
14
15
R4
220Ω
Q
=
2
R2
2N3906
R5
–15V
+V
2
R6
S
R3
A2
16 –V
S
5
9
10
8
12
11
13
Figure 40. Bipolar Bridge Drive
+15V
220Ω
Q
1
=
2N3904
6
4
7
3
AD OP-07
A3
A4
1
R
B
+
V
–
A1
R1
OUT
AD588
14
15
R1
R2
R4
R5
220Ω
Q
=
2
R2
2N3906
–15V
2
+V
R6
S
R3
A2
16
–V
S
5
9
10
8
12
11
13
Figure 41. Floating Bipolar Bridge Drive with Minimum CMV
Rev. M | Page 18 of 20
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