MAX4444 Maxim, MAX4444 Datasheet - Page 8

• Manufacturer Part Number: MAX4444
• Description: The MAX4444/MAX4445 differential line receivers offer unparalleled high-speed, low-distortion performance
• Manufacturer: Maxim

The MAX4444/MAX4445 differential-to-single-ended
line receivers offer high-speed and low-distortion per-
formance, and are ideally suited for video and RF sig-
nal-processing applications. These receivers offer a
small-signal bandwidth of 550MHz and have a high
slew rate of up to 5000V/µs. Their 120mA output capa-
bility allows them to be directly coupled to data acquisi-
tion systems.
Use the following high-frequency design techniques
when designing the PC board for the MAX4444/
MAX4445.
• Use a multilayer board with one layer dedicated as
• Do not use wire wrap or breadboards due to high
• Avoid IC sockets due to high parasitic capacitance
• Bypass supplies with a 0.1µF capacitor. Use sur-
• Keep signal lines as short and straight as possible.
• Ensure that the ground plane is free from voids.
The MAX4444/MAX4445 are disabled when EN goes
low. This reduces supply current to only 3.5mA. As the
output becomes higher impedance, the effective
impedance at the output for the MAX4444 is 1.8kΩ. The
effective output impedance for the MAX4445 is 1.8kΩ
plus R
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.
8 _____________________Maxim Integrated Products, 120 San Gabriel Drive, Sunnyvale, CA 94086 408-737-7600
© 1999 Maxim Integrated Products
Ultra-High-Speed, Low-Distortion, Differential-
to-Single-Ended Line Receivers with Enable
Figure 1. Setting the Amplifier Gain
_______________Detailed Description
__________Applications Information
the ground plane.
inductance.
and inductance.
face-mount capacitors to minimize lead inductance.
Do not make 90° turns. Use rounded corners. Do not
cross signal paths if possible.
GAIN
R
.
GAIN
RG
RG
MAX4445
Low-Power Enable Mode
GAIN = 1 + 600
Grounding Bypassing
R
GAIN
Printed USA
The MAX4445 is stable with a minimum gain configura-
tion of +2V/V. R
sets the gain of this device as shown in Figure 1.
Calculate the expected gain as follows:
The MAX4444/MAX4445 are designed to drive capaci-
tive loads. However, excessive capacitive loads may
cause ringing or instability at the output as the phase
margin of the device reduces. Adding a small series
isolation resistor at the output helps reduce the ringing
but slightly increases gain error (Figure 2). For recom-
mended values, see Typical Operating Characteristics .
The MAX4444/MAX4445 are well suited to drive coaxial
cables. Their high output current capability can easily
drive the 75Ω characteristic impedance of common
coaxial cables. Adjust the gain of the MAX4445 to com-
pensate for cable losses to maintain the required levels
at the input of the next stage.
TRANSISTOR COUNT: 254
SUBSTRATE CONNECTED TO V
Figure 2. Using an Isolation Resistor for High Capacitive Loads
is a registered trademark of Maxim Integrated Products.
IN–
IN +
MAX4444
MAX4445
Gain = (1 + 600 / R
GAIN
, connected between the RG pins,
Driving Capacitive Loads
Setting Gain (MAX4445)
Chip Information
R
ISO
Coaxial Line Driver
EE
GAIN
)
C
LOAD