MAX7490CEE+T Maxim Integrated Products, MAX7490CEE+T Datasheet - Page 14

• Manufacturer Part Number: MAX7490CEE+T
• Description: IC FILTER SW CAP DUAL 16-QSOP
• Manufacturer: Maxim Integrated Products

Specifications of MAX7490CEE+T

• Filter Type: Universal Switched Capacitor
• Frequency - Cutoff Or Center: 40kHz
• Number Of Filters: 2
• Max-order: 2nd
• Voltage - Supply: 4.5 V ~ 5.5 V
• Mounting Type: Surface Mount
• Package / Case: 16-QSOP
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Dual Universal Switched-Capacitor Filters
Mode 3A Design Equations
Note: When the passband gain error exceeds 1dB, the
use of capacitor C
the inverting input will reduce the gain error. The value
can best be determined experimentally. Typically, it
should be about 5pF/dB (C
14
Table 3. Suggested External Op Amps
Figure 8. Block Diagram of a 2nd-Order Section Showing the Input Offsets
______________________________________________________________________________________
MAX4281
MAX4322
MAX4130
MAX4490
PART
f
f
Q
H
H
H
H
H
O
n
OHP
OLP
OBP
ON
ON
=
=
=
R
R
1
2
f
f
100
CLK
100
(
CLK
3
2
(
f
=
at f
=
=
→
−
−
−
R
R
R
R
R
R
R
R
C
0
=
1
1
1
INV
COM
2
4
4
2
3
Hz
R
R
R
f
R
between the lowpass output and
CLK
H
L
2
4
)
=
V
OS1
R
/ )
R
C-MAX
2
G
L
GBW (MHz)
=
⎛
⎜
⎝
R
R
R
R
4
10
10
1
G
H
2
5
= 15pF).
⎞
⎟
⎠
⎛
⎜
⎝
R
R
2
1
⎞
⎟
⎠
N/HP
+
SLEW RATE (V/μs)
Σ
S
-
10.0
0.7
2.0
4.0
V
OS2
Switched-capacitor integrators generally exhibit higher
input offsets than discrete RC integrators. The larger
offset is mainly due to the charge injection of the CMOS
switches into the integrating capacitors. The internal op
amp offset also adds to the overall offset value. Figure
8 shows the input offsets from a single 2nd-order sec-
tion. Table 4 lists the formula for the output offset volt-
age for various modes and output pins.
The MAX7490 operates from a single +5V supply, and
the MAX7491 operates from a single +3V supply.
Bypass V
V
age analog supplies. If dual supplies are required, con-
nect the COM pin to the system ground and the GND
pin to the negative supply. Figure 9 shows an example
of dual-supply operation. Single-supply and dual-sup-
ply performances are equivalent. For dual-supply oper-
ation, drive CLK, SHDN, and EXTCLK from GND (which
is now V-) to V
supply mode, C
the actual ground voltage. Use the MAX7490 for ±2.5V
and use the MAX7491 for ±1.5V.
For most applications, a 0.1µF bypass capacitor from
COM to GND is sufficient. If the V
cant 60Hz energy, increase this capacitor to 1µF or
greater to provide better power-supply rejection.
DD
∫
should be isolated from other digital or high-volt-
DD
I SUPPLY/AMP (mA)
BP
to GND with at least a 0.1µF capacitor.
DD
OSC
V
. If using the internal oscillator in dual-
OS3
1.15
0.5
1.1
2.0
can be returned to either GND or
∫
LP
DD
Power Supplies
Offset Voltage
PIN-PACKAGE
supply has signifi-
5 SOT23
5 SOT23
5 SOT23
5 SOT23