OP179_02 Datasheet, PDF (10/16 Pages) Analog Devices – Rail-to-Rail High Output Current Operational Amplifiers

OP179/OP279
TO TELEPHONE
LINE
1:1
R3
55⍀
Z_O
110⍀
T1
6.2V
6.2V
R4
55⍀
P1
TX GAIN
ADJUST
R2
9.09k⍀
2k⍀
2
1
R5
10k⍀
A1 ₃
R1
10k⍀
C1
0.1␮F
TRANSMIT
TXA
R6
10k⍀ ₇
6
A2 ₅
5V DC
10␮F
R7
10k⍀
R8
10k⍀
R9
10k⍀
R10
10k⍀
R11
10k⍀
2
1
3 ^A3
R12
A1, A2 = 1/2 OP279 ^10k⍀
A3, A4 = 1/2 OP279
R13
10k⍀
P2
RX GAIN
R14 ADJUST
9.09k⍀
RECEIVE
RXA
6
2k⍀ _C2
5 ^A4
7
0.1␮F
Figure 10. A Single-Supply Direct Access Arrangement for
Modems
A Single-Supply, Remote Strain Gage Signal Conditioner
The circuit in Figure 11 illustrates a way by which the OP179/
OP279 can be used in a 12 V single supply, 350 Ω strain gage
signal conditioning circuit. In this circuit, the OP179/OP279
serves two functions: (1) By servoing the output of the REF43’s
2.5 V output across R1, it provides a 20 mA drive to the 350 Ω
strain gage. In this way, small changes in the strain gage pro-
duce large differential output voltages across the AMP04’s
inputs. (2) To maximize the circuit’s dynamic range, the other
half of the OP179/OP279 is configured as a supply-splitter
connected to the AMP04’s REF terminal. Thus, tension or
compression in the application can be measured by the circuit.
12V
2
8
1
3 ^2.5V 6
REF43
0.1␮F
F+
A1 ₂
4
4
20mA DRIVE
S+
S–
100-ft TWISTED PAIR
BELDEN TYPE 9502
F–
350⍀
STRAIN GAGE
C1
10␮F
12V _R4 C2
1k⍀ ^0.1␮F
7
C_X
R1
3
1
8
AMP04 ⁶
2
45
V_O
80mV/⍀
124⍀
0.1%, LOW TCR
V_O
COMMON
12V
R2
10k⍀
6
5 ^A2
7 _+6V
R3
10k⍀
A1, A2 = 1/2 OP279
Figure 11. A Single-Supply, Remote Strain Gage Signal
Conditioner
The AMP04 is configured for a gain of 100, producing a circuit
sensitivity of 80 mV/Ω. Capacitor C2 is used across the AMP04’s
Pins 8 and 6 to provide a 16-Hz noise filter. If additional noise
filtering is required, an optional capacitor, C_X, can be used across
the AMP04’s input to provide differential-mode noise rejection.
A Single-Supply, Balanced Line Driver
The circuit in Figure 12 is a unique line driver circuit topology
used in professional audio applications and has been modified
for automotive audio applications. On a single 12 V supply, the
line driver exhibits less than 0.02% distortion into a 600 Ω load
across the entire audio band (not shown). For loads greater than
600 Ω, distortion performance improves to where the circuit
exhibits less than 0.002%. The design is a transformerless, balanced
transmission system where output common-mode rejection of
noise is of paramount importance. Like the transformer-based
system, either output can be shorted to ground for unbalanced
line driver applications without changing the circuit gain of 1.
Other circuit gains can be set according to the equation in the
diagram. This allows the design to be easily configured for
noninverting, inverting, or differential operation.
R2
10k⍀
12V
C1 ²
22␮F _{3 A1} ¹
V_IN
R1
10k⍀
A1, A2 = 1/2 OP279
GAIN
=
R3
R2
SET: R7, R10, R11 = R2
SET: R6, R12, R13 = R3
R3
10k⍀
2
1
3 ^A2
R5
50⍀
R6
10k⍀
R7
10k⍀
12V
6
7
A1 ₅
12V
R8
100k⍀
R9 C2
100k⍀ 1␮F
R11 _R12
10k⍀ _10k⍀
6
5 ^{A2 7}
R13
10k⍀
R14
50⍀
C3
47␮F
V_O1
R_L
600⍀
C4
47␮F
V_O2
Figure 12. A Single-Supply, Balanced Line Driver for
Automotive Applications
–10–
REV. G