MAX3762EEP-T Maxim Integrated, MAX3762EEP-T Datasheet - Page 8

• Manufacturer Part Number: MAX3762EEP-T
• Description: Limiting Amplifiers 622Mbps w/Chatter Free Power Detect
• Manufacturer: Maxim Integrated

Specifications of MAX3762EEP-T

• Operating Supply Voltage: 5 V
• Supply Current: 30 mA
• Operating Temperature Range: + 85 C
• Package / Case: QSOP-20
• Available Set Gain: 12.5 dB
• Mounting Style: SMD/SMT
• Number Of Channels: 1
• Power Dissipation: 591 mW

A typical MAX3761/MAX3762 implementation requires
four external capacitors. To select the capacitors, first
determine the following parameters in the receiver sys-
tem (see the Applications Information section for rec-
ommendations in 622Mbps ATM and Fibre Channel
1063Mbps systems):
1) The duration of the expected longest run of consec-
2) The maximum allowable data-dependent jitter.
3) The desired power-detector integration time con-
4) The transimpedance amplifier’s maximum peak-to-
Step 1. Select the Input AC-Coupling Capacitors (C
When using a limiting preamplifier with a highpass
frequency response, select C
frequency cutoff (f
preamplifier low-frequency cutoff. This causes nearly all
data-dependent jitter (DDJ) to be generated in the pre-
amplifer circuit. For example, if the preamplifier’s low-
frequency cutoff is 150kHz, then select C
15kHz low-frequency cutoff.
Select C
For differential input signals, use a capacitor equal to
C
input signals, one capacitor should be tied to VIN+ and
another should decouple VIN- to ground.
When using a preamplifier without a highpass
response, select C
ter is acceptable. The following equation provides an
estimate for C
where: t
bits with the same value (seconds); DDJ = maximum
allowable data-dependent jitter, peak-to-peak (seconds);
BW = typical system bandwidth, normally 0.6 to 1.0
times the data rate (hertz).
Regardless of which method is used to select C
maximum LOS assert time can be estimated from the
Low-Power, 622Mbps Limiting Amplifiers
with Chatter-Free Power Detect for LANs
8
IN
utive bits in the data stream. For example, 72 con-
secutive zeros in a 622Mbps data stream have a
duration of 116ns.
stant [1 / (2πf
peak output voltage.
_______________________________________________________________________________________
on both inputs (VIN+ and VIN-). For single-ended
IN
L
C
with the following equation:
= duration of the longest run of consecutive
IN
IN
INT
:
≥
C
)].
IN
1950
IN
C
to ensure that data-dependent jit-
=
) one decade lower than the
ln
2 f 1950
π
⎡
⎢
⎢
⎣
1
C
−
Capacitor Selection
-
1
t
(
L
DDJ BW
IN
Ω
0 5
to provide a low-
)(
.
IN
)
⎤
⎥
⎥
⎦
to provide a
IN
, the
IN
).
value of C
delay when the maximum-amplitude signal is instanta-
neously removed from the input, and when the FILTER
time constant is much faster than the input time con-
stant (C
where V
fier, and V
LOS to assert. The equation describes the input capac-
itors’ discharge time, from maximum input to the LOS
threshold into the 1950Ω, single-ended input resis-
tance.
Step 2. Select the Offset-Correction Capacitor (C
To maintain stability, it is important to keep a one-
decade separation between f
cutoff associated with the DC-offset-correction circuit
(f
The input impedance between CZP and CZN is
approximately 800kΩ in parallel with 10pF. As a result,
the low-frequency cutoff (f
offset-correction loop is computed as follows:
where C
CZP and CZN.
If C
Step 3. Select the Power-Detect Integration Capacitor
(C
ommends a filter frequency of 3MHz, which requires
C
selected lower to remove low-frequency noise, or to
prevent unusual data sequences from asserting LOS.
where f
OC
FILTER
FILTER
IN
).
t
LOS ASSERT
is known, then:
INT
FILTER
MAXp-p
= 100pF. The integration frequency can be
AZ
). For 622Mbps ATM applications, Maxim rec-
IN
ASSERTp-p
is the integration frequency.
f
. The following equation estimates LOS time
is an optional external capacitor between
OC
C
< 0.4C
FILTER
is the maximum output of the preampli-
=
= 1950C
C
2 800k
AZ
π
is the input amplitude that causes
IN
= 1 / ( 2π500f
):
≥
C
OC
41
Ω C
IN
IN
ln(V
) associated with the DC-
(
C
−
1
10
AZ
and the low-frequency
MAXp-p
pF
+
INT
10
)
pF
/ V
)
ASSERTp-p
AZ
)
).