19-1768; Rev 1; 4/09
Dual Universal Switched-Capacitor Filters
The MAX7490/MAX7491 consist of two identical lowpower, low-voltage, wide dynamic range, rail-to-rail,
2nd-order switched-capacitor building blocks. Each of
the two filter sections, together with two to four external
resistors, can generate all standard 2nd-order functions: bandpass, lowpass, highpass, and notch (band
reject). Three of these functions are simultaneously
available. Fourth-order filters can be obtained by cascading the two 2nd-order filter sections. Similarly, higher order filters can easily be created by cascading
multiple MAX7490/MAX7491s.
Two clocking options are available: self-clocking
(through the use of an external capacitor) or external
clocking for tighter cutoff frequency control. The clockto-center frequency ratio is 100:1. Sampling is done at
twice the clock frequency, further separating the cutoff
frequency and Nyquist frequency.
The MAX7490/MAX7491 have an internal rail splitter
that establishes a precise common voltage needed for
single-supply operation. The MAX7490 operates from a
single +5V supply and the MAX7491 operates from a
single +3V supply. Both devices feature a low-power
shutdown mode and come in a 16-pin QSOP package.
________________________Applications
Tunable Active Filters
Multipole Filters
ADC Anti-Aliasing
Post-DAC Filtering
Adaptive Filtering
Phase-Locked Loops (PLLs)
Features
o Dual 2nd-Order Filter in a 16-Pin QSOP Package
o High Accuracy
Q Accuracy: ±0.2%
Clock-to-Center Frequency Error: ±0.2%
o Rail-to-Rail Input and Output Operation
o Single-Supply Operation: +5V (MAX7490)
or +3V (MAX7491)
o Internal or External Clock
o Highpass, Lowpass, Bandpass, and Notch Filters
o Clock-to-Center Frequency Ratio of 100:1
o Internal Sampling-to-Center Frequency Ratio
of 200:1
o Center Frequency up to 40kHz
o Easily Cascaded for Multipole Filters
o Low-Power Shutdown: < 1µA Supply Current
Ordering Information
PART
TEMP RANGE
SUPPLY
PINVOLTAGE
PACKAGE
(+V)
MAX7490CEE+
0°C to +70°C
16 QSOP
5
MAX7490EEE+
-40°C to +85°C
16 QSOP
5
MAX7491CEE+
0°C to +70°C
16 QSOP
3
MAX7491EEE+
-40°C to +85°C 16 QSOP
+Denotes a lead(Pb)-free/RoHS-compliant package.
3
Set-Top Boxes
Pin Configuration
TOP VIEW
+
LPA 1
16 LPB
BPA 2
15 BPB
14 NB/HPB
NA/HPA 3
Typical Application Circuit appears at end of data sheet.
INVA 4
SA 5
MAX7490
MAX7491
SHDN 6
13 INVB
12 SB
11 COM
GND 7
10 EXTCLK
VDD 8
9
CLK
QSOP
________________________________________________________________ Maxim Integrated Products
For pricing, delivery, and ordering information, please contact Maxim Direct at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
1
MAX7490/MAX7491
General Description
