OP462_15 Datasheet, PDF (17/20 Pages) Analog Devices – 15 MHz Rail-to-Rail Operational Amplifiers

Data Sheet
5mV
2V
100
90
10
0%
1µs
Figure 45. Positive Slope Settling Time
5mV
2V
100
90
10
0%
1µs
Figure 46. Negative Slope Settling Time
OP162/OP262/OP462
DIRECT ACCESS ARRANGEMENT
Figure 47 shows a schematic for a 5 V single-supply transmit/
receive telephone line interface for 600 Ω transmission systems.
It allows full-duplex transmission of signals on a transformer-
coupled 600 Ω line. Amplifier A1 provides gain that can be
adjusted to meet the modem output drive requirements. Both
A1 and A2 are configured to apply the largest possible differential
signal to the transformer. The largest signal available on a single
5 V supply is approximately 4.0 V p-p into a 600 Ω transmission
system. Amplifier A3 is configured as a difference amplifier to
extract the receive information from the transmission line for
amplification by A4. A3 also prevents the transmit signal from
interfering with the receive signal. The gain of A4 can be adjusted
in the same manner as A1 to meet the modem’s input signal
requirements. Standard resistor values permit the use of SIP
(single in-line package) format resistor arrays. Couple this with
the OP462 14-lead SOIC or TSSOP package and this circuit
offers a compact solution.
TO TELEPHONE
LINE
1:1
Z_O
600Ω
6.2V
6.2V
R3
360Ω
T1
MIDCOM
671-8005
P1
TX GAIN
ADJUST
R2
9.09kΩ
2k
1
R5
10kΩ
2
A1 ₃
R1
10kΩ
C1
0.1µF
TRANSMIT
TXA
R6
10kΩ
7
6
A2 ₅
5V DC
R7
10kΩ
10µF
R8
10kΩ
R9
10kΩ
R10
10kΩ
R11
10kΩ
2
3 ^{A3 1}
R12
A1, A2 = 1/2 AD8532 ^10kΩ
A3, A4 = 1/2 AD8532
R13
10kΩ
P2
RX GAIN
R14 ADJUST
14.3kΩ
RECEIVE
RXA
6
2kΩ
7
5 ^A4
C2
0.1µF
Figure 47. Single-Supply Direct Access Arrangement for Modems
Rev. H | Page 17 of 20