MAX4449ESE+T

MAX4447/MAX4448/MAX4449
6500V/µs, Wideband, High-Output-Current, Single-
Ended-to-Differential Line Drivers with Enable
10 ______________________________________________________________________________________
Detailed Description
The MAX4447/MAX4448/MAX4449 single-ended-to-dif-
ferential converters are capable of transmitting high-
speed signals such as T1 or xDSL over twisted-pair
cable. Excellent gain and phase characteristics, along
with low distortion, make these devices suitable for
video and RF signal processing and transmission.
These converters can be interfaced directly to some of
Maxim’s wireless products, such as the MAX2450/
MAX2451.
The MAX4447/MAX4448/MAX4449 offer wide small-sig-
nal bandwidths of 430MHz, 330MHz, and 400MHz,
respectively. Internally trimmed resistors minimize gain
errors to under 2% over the full output range. Other fea-
tures include a high slew rate up to 6500V/µs and high
output current (130mA), which allow these amplifiers to
be used in numerous high-speed communications
applications.
Applications Information
Grounding and Bypassing
Use high-frequency design techniques when designing
the PC board for the MAX4447/MAX4448/MAX4449:
Use a multilayer board with one layer dedicated as
the ground plane.
Do not wire-wrap or use breadboards, due to high
inductance.
Avoid IC sockets, due to high parasitic capacitance
and inductance.
Bypass supplies with 0.1µF. Use surface-mount
capacitors to minimize lead inductance.
Keep signal lines as short and straight as possible.
Do not make 90° turns; round all corners. Do not
cross signals if possible.
Ensure that the ground plane is free from voids.
Output Short-Circuit Protection
Output short-circuit protection typically limits the cur-
rent to 140mA when shorted to GND, thereby keeping
the power dissipation under the absolute maximum
power dissipating rating. However, when shorted to
either supply, the short-circuit current can be signifi-
cantly higher and cause damage to the device.
Low-Power Enable Mode
The MAX4447/MAX4448/MAX4449 are disabled when
EN goes low. This reduces supply current to only
3.2mA and places the outputs into a higher impedance.
MAX4448
MAX4449
V
EE
V
CC
R
GAIN
RG
IN
OUT+
A
VCL
= 2 ( 1 + )
OUT-
300
R
GAIN
INPUT
Figure 1. Setting the Amplifier Gain
MAX4447
MAX4448
MAX4449
R
GAIN
RG
IN
OUT+
C
LOAD
R
ISO
R
ISO
OUT-
C
LOAD
V
CC
V
EE
INPUT
Figure 2. Using an Isolation Resistor for High Capacitive Loads
Setting Gain
The MAX4448/MAX4449 are stable with minimum gain
of +2V/V and +5V/V, respectively. An external resistor,
R
GAIN
, connected between RG and GND sets the gain
of these devices. Calculate the gain as follows:
Gain = 2 (1 + 300 / R
GAIN
)
R
GAIN
for the MAX4449 must be 200.
Driving Capacitive Loads
The MAX4447/MAX4448/MAX4449 are designed to
drive capacitive loads. However, excessive capacitive
loads may cause ringing or instability at the output as
phase margin is reduced. Adding a small series isola-
tion resistor at the output helps reduce the ringing but
slightly increases gain error.
Twisted-Pair Line Driver
The MAX4447/MAX4448/MAX4449 are well-suited to
drive twisted-pair cables. The 24AWG telephone wire
widely used produces losses at the higher frequencies.
Compensate for these losses by increasing the gain
slightly.
MAX4447/MAX4448/MAX4449
6500V/µs, Wideband, High-Output-Current, Single-
Ended-to-Differential Line Drivers with Enable
______________________________________________________________________________________ 11
IN
500mV/div
OUT
1V/div
C
L
= 15pF
IN
500mV/div
OUT
1V/div
C
L
= 15pF
Figure 3. Capacitive-Loaded Output Step Response Without
Isolation Resistor
Figure 4. Capacitive-Loaded Output Step Response with 14
Isolation Resistor
Chip Information
TRANSISTOR COUNT: 291
MAX4447/MAX4448/MAX4449
6500V/µs, Wideband, High-Output-Current, Single-
Ended-to-Differential Line Drivers with Enable
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Maxim cannot assume responsibility for use of any circuitry other than circuitry entirely embodied in a Maxim product. No circuit patent licenses are
implied. Maxim reserves the right to change the circuitry and specifications without notice at any time.
12 ____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products Printed USA is a registered trademark of Maxim Integrated Products.
Package Information
SOICN.EPS

MAX4449ESE+T

Mfr. #:
Manufacturer:
Maxim Integrated
Description:
Buffers & Line Drivers 6500V/uM 400MHz Line Receiver
Lifecycle:
New from this manufacturer.
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