MAX19790ETX+T Maxim Integrated Products, MAX19790ETX+T Datasheet - Page 9

• Manufacturer Part Number: MAX19790ETX+T
• Description: Active Attenuator 250MHz to 4000MHz Du al, Analog Voltage V
• Manufacturer: Maxim Integrated Products

Specifications of MAX19790ETX+T

• Mounting Style: SMD/SMT
• Package / Case: QFN-36
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

The MAX19790 is a dual, general-purpose analog volt-
age variable attenuator (VVA) designed to interface
with 50I systems operating in the 250MHz to 4000MHz
frequency range. Each attenuator includes a control
circuit that provides 22dB of attenuation range with a
linear control slope of 10dB/V. Both attenuators share a
common analog control and can be cascaded together
to yield 44dB of total dynamic range, with a combined
linear control slope of 20dB/V.
A single input voltage at the CTRL pin adjusts the attenu-
ation of the device. Up to 22dB of attenuation-control
range is provided per attenuator. At the insertion-loss
setting, the attenuator’s loss is approximately 2.4dB.
If a larger attenuation-control range is desired, the
second on-chip attenuator can be connected in series to
provide an additional 22dB of gain-control range.
Note that the CTRL pin simultaneously adjusts both
on-chip attenuators. The CTRL input voltage drives a
high-impedance load (> 50kI). It is suggested that a
current-limiting resistor be included in series with this
Table 1. Typical Application Circuit Component Values
*C8 can be used to provide additional filtering. Depending on the external driver used on the CTRL line, this capacitance could
slow down the response time.
DESIGNATION
C1, C3, C5
C2, C4
C8*
C6
C7
Applications Information
QTY
3
2
1
1
0
Analog Attenuation Control
Detailed Description
220pF Q5%, 50V C0G ceramic
capacitors (0402)
Murata GRM1555C1H221J
0.01FF Q10%, 25V X7R ceramic
capacitors (0402)
Murata GRM155R71E103K
1000pF Q5%, 50V C0G ceramic
capacitor (0402)
Murata GRM1555C1H102J
0.1FF Q10%, 16V X7R ceramic
capacitor (0603)
Murata GRM188R71C104K
Not installed, ceramic capacitor
(0603)
Analog Voltage Variable Attenuator
DESCRIPTION
250MHz to 4000MHz Dual,
connection, to limit the input current to less than 40mA,
should the control voltage be applied when V
present. A series resistor of greater than 200I provides
complete protection for +5.0V control voltage ranges.
Note: To ensure the reliability of the device, limit CTRL
input voltages to a +1.0V to +4.0V range when V
present.
A properly designed PCB is an essential part of any
RF/microwave circuit. Keep RF signal lines as short as
possible to reduce losses, radiation, and inductance.
For best performance, route the ground-pin traces
directly to the exposed pad underneath the package.
This pad MuST be connected to the ground plane of
the board by using multiple vias under the device to
provide the best RF and thermal conduction path. Solder
the exposed pad on the bottom of the device package
to a PCB.
Proper voltage-supply bypassing is essential for high-
frequency circuit stability. Bypass each V
capacitors placed as close as possible to the device.
Place the smallest capacitor closest to the device. See
the Typical Application Circuit and Table 1 for details.
DESIGNATION
R1, R2
R3, R4
C9
U1
QTY
1
2
2
1
22pF Q5%, 50V C0G ceramic
capacitor (0402)
Murata GRM1555C1H220J
10I Q5% resistors (0402)
Any
0I resistors (0402)
Note: In cases where V
applied before or removed after
V
Analog attenuator IC
Maxim MAX19790ETX+
Note: U1 has an exposed pad
conductor, which requires it to be
solder-attached to a grounded
pad on the PCB to ensure a
proper electrical/thermal design.
Power-Supply Bypassing
CC
Layout Considerations
, use R4 = 200I.
DESCRIPTION
CC
CTRL
CC
pin with
is not
is
CC
is
9