Datasheet

AD588
Rev. L | Page 18 of 20
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.
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.
00531-040
R3
R
B
R1
R2
R4
R5
R6
–V
S
+V
S
A1
A4
AD588
A3
Q
1
=
2N3904
220Ω
+15V
–15V
220Ω
Q
2
=
2N3906
E
O
+–
13
11
12
8109
5
1
14
15
2
16
3
46
7
A2
Figure 40. Bipolar Bridge Drive
00531-041
R3
R
B
R1
R2
R4
R5
R6
–V
S
+V
S
A1
A4
AD588
A3
R1
R2
AD OP-07
V
OUT
+
–
220Ω
+15
V
–15V
220Ω
Q
1
=
2N3904
Q
2
=
2N3906
13
11
12
8109
5
1
14
15
2
16
3
4
6
7
A2
Figure 41. Floating Bipolar Bridge Drive with Minimum CMV