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MAX4145ESD+

P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16
MAX4144/MAX4145/MAX4146
High-Speed, Low-Distortion,
Differential Line Receivers
______________________________________________________________________________________ 13
which appears inductive at high frequencies. This
inductance forms an L-C resonant circuit with the
capacitive load, which causes peaking in the frequency
response and degrades the amplifier’s phase margin.
The MAX4144/MAX4145/MAX4146 drive capacitive
loads up to 25pF without oscillation. However, some
peaking may occur in the frequency domain (Figure 4).
To drive larger capacitance and reduce ringing, add an
isolation resistor (R
ISO
) between the amplifier’s output
and the load (Figure 5).
The value of R
ISO
depends on the circuit’s gain and the
capacitive load (Figures 6 and 7). With higher capaci-
tive values, bandwidth is dominated by the RC network
formed by R
ISO
and C
L
; the bandwidth of the amplifier
itself is much higher. Also note that the isolation resistor
forms a divider that decreases the voltage delivered to
the load.
Twisted-Pair Line Receiver
The MAX4144/MAX4145/MAX4146 are well suited as
receivers in twisted-pair xDSL or NTSC/PAL video
applications. The standard 24AWG telephone wire
widely used in these applications is a lossy medium for
high-frequency signals. The losses in NTSC video
applications are almost 15dB per 1000 feet (Figure 8).
4
0
8
6
CAPACITIVE LOAD (pF)
ISOLATION RESISTANCE (Ω)
200
16
18
12
10
14
50 150 250
20
100
A
V
= 10V/V
Figure 6. MAX4144 Isolation Resistance vs. Capacitve Load
0
0
5
CAPACITIVE LOAD (pF)
ISOLATION RESISTANCE (Ω)
200
25
15
10
20
50 150 250
30
100
Figure 7. MAX4145/MAX4146 Isolation Resistance vs.
Capacitive Load
R
LOAD
C
LOAD
R
ISO
OUT
MAX4144
MAX4145
MAX4146
Figure 5. Addition of R
ISO
to Amplifier Output
15
-35
-30
-25
10k 1M 10M
-20
-15
-10
-5
0
5
10
100k
FREQUENCY (Hz)
GAIN (dB)
Figure 8. 1000 Feet of 24AWG Twisted-Pair Telephone Cable
(Gain vs. Frequency)
MAX4144/MAX4145/MAX4146
High-Speed, Low-Distortion,
Differential Line Receivers
14 ______________________________________________________________________________________
TWISTED-PAIR-TO-COAX CABLE CONVERTER
Losses are higher at higher frequencies, contributing to
severe pulse-edge rounding in digital applications. The
nominal impedance of twisted-pair telephone wire is
110Ω.
The MAX4145/MAX4146, with variable gain up to
+10V/V and +100V/V, respectively, can be used to
compensate for cable losses. In the graph shown in
Figure 8, the cable characteristics are such that the
video-chroma frequency loss is almost 15dB greater
than the low-frequency loss. The losses can be com-
pensated for by using the RC-shaping network (Figure
9).
A 560Ω resistance and a 100pF capacitance shape the
MAX4146 gain to inversely match the frequency of the
1000 feet of telephone cable. The differential gain and
phase, using the circuit shown in Figure 9, is 0.55%
and 0.18°, respectively.
Figure 9. Circuit for Transmitting NTSC/PAL Video Over 1000 Feet of Twisted-Pair Telephone Line
VIDEO INPUT
VIDEO
OUTPUT
75Ω
75Ω
1, 7
8, 14
10
12
9
13
1000 FEET
2
6
MAX4147ESD
0.1μF
V
CC
0.1μF
V
EE
0.1μF
11
9
13
75Ω
2
110Ω
560Ω
100pF
6
5
3
V
CC
V
EE
MAX4146ESD
0.1μF
1, 7
8, 14
OUT+
IN+
IN-
IN-
SENSE
IN+
OUT-
SENSE-
SENSE+
R
T
R
T
R
T
R
T
OUT
REF
75Ω
75Ω
COAX
75Ω
V
OUT
MAX4147
MAX4144
__________________________________________________Typical Application Circuit
MAX4144/MAX4145/MAX4146
High-Speed, Low-Distortion,
Differential Line Receivers
______________________________________________________________________________________ 15
Pin Configurations
14
13
12
11
10
9
8
1
2
3
4
5
6
7
V
CC
SENSE
N.C.
OUT
SHDN
N.C.
IN-
V
EE
TOP VIEW
MAX4144
N.C.
REF
V
CC
V
EE
IN+
N.C.
SO
R
F
RR
SENSE
R
REF
R
R
F
R
G
14
13
12
11
10
9
8
1
2
3
4
5
6
7
V
CC
SENSE
N.C.
OUT
SHDN
RG-
IN-
V
EE
MAX4145
MAX4146
N.C.
REF
V
CC
V
EE
IN+
RG+
R
F
RR
SENSE
R
REF
R
R
F
SO
16
15
14
13
12
11
10
1
2
3
4
5
6
7
V
CC
SENSE
N.C.
OUT
SHDN
N.C.
IN-
V
EE
MAX4144
N.C.
REF
V
CC
V
EE
IN+
9
8
N.C
N.C.
N.C.
QSOP
R
F
RR
SENSE
R
REF
R
R
F
R
G
16
15
14
13
12
11
10
1
2
3
4
5
6
7
V
CC
SENSE
N.C.
OUT
SHDN
RG-
IN-
V
EE
MAX4145
MAX4146
N.C.
REF
V
CC
V
EE
9
8
N.C.
N.C.
IN+
RG+
R
F
RR
SENSE
R
REF
R
R
F
QSOP
Chip Information
TRANSISTOR COUNT: 237
SUBSTRATE CONNECTED TO V
EE
PACKAGE TYPE PACKAGE CODE DOCUMENT NO.
14 SO S14-1
21-0041
16 QSOP E16-4
21-0055
Package Information
For the latest package outline information and land patterns, go
to www.maxim-ic.com/packages
.
P1-P3P4-P6P7-P9P10-P12P13-P15P16-P16

MAX4145ESD+

Mfr. #:
Buy MAX4145ESD+
Manufacturer:
Maxim Integrated
Description:
Differential Amplifiers
Lifecycle:
New from this manufacturer.
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