General Description
The MAX7490/MAX7491 consist of two identical low-
power, 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 func-
tions: bandpass, lowpass, highpass, and notch (band
reject). Three of these functions are simultaneously
available. Fourth-order filters can be obtained by cas-
cading the two 2nd-order filter sections. Similarly, high-
er 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 clock-
to-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)
Set-Top Boxes
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
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
________________________________________________________________
Maxim Integrated Products
1
16
15
14
13
12
11
10
9
1
2
3
4
5
6
7
8
LPA LPB
BPB
NB/HPB
INVB
SB
COM
EXTCLK
CLK
TOP VIEW
MAX7490
MAX7491
QSOP
+
BPA
NA/HPA
SHDN
INVA
SA
GND
V
DD
Pin Configuration
19-1768; Rev 1; 4/09
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.
Ordering Information
PART TEMP RANGE
PIN-
PACKAGE
SUPPLY
VOLTAGE
(+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 3
Typical Application Circuit appears at end of data sheet.
+
Denotes a lead(Pb)-free/RoHS-compliant package.
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS—MAX7490
(V
DD
= V
EXTCLK
= +5V; f
CLK
= 625kHz; 10kΩ || 50pF load to V
DD
/2 at LP_, BP_, and N_/HP_; V
SHDN
= V
DD
; 0.1µF from COM to
GND; 50% duty-cycle clock input; COM = V
DD
/2; T
A
= T
MIN
to T
MAX
. Typical values are at T
A
= +25°C, unless otherwise noted.)
(Note 1)
Stresses beyond those listed under “Absolute Maximum Ratings” may cause permanent damage to the device. These are stress ratings only, and functional
operation of the device at these or any other conditions beyond those indicated in the operational sections of the specifications is not implied. Exposure to
absolute maximum rating conditions for extended periods may affect device reliability.
V
DD
to GND..............................................................-0.3V to +6V
EXTCLK, SHDN to GND ...........................................-0.3V to +6V
INV_, LP_, BP_, N_/HP_, S_, COM,
CLK to GND............................................-0.3V to (V
DD
+ 0.3V)
Maximum Current into Any Pin ...........................................50mA
Continuous Power Dissipation (T
A
= +70°C)
16-Pin QSOP (derate 8.30mW/°C above +70°C).........667mW
Operating Temperature Range
MAX749_CEE .....................................................0°C to +70°C
MAX749_EEE...................................................-40°C to +85°C
Die Temperature ..............................................................+150°C
Storage Temperature.........................................-65°C to +150°C
Lead Temperature (soldering, 10s) .................................+300°C
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
FILTER
Center Frequency Range f
O
Mode 1
0.001 to
40
kHz
Clock-to-Center Frequency
Accuracy
f
CLK
/f
O
Mode 1, R1 = R3 = 50kΩ , R2 = 10kΩ,
Q = 5, deviation from 100:1
±0.2 ±0.7 %
Q Accuracy M od e 1, R1 = R3 = 50kΩ, R2 = 10kΩ, Q = 5 ±0.2 ±2%
f
O
Temperature Coefficient ±1 ppm/°C
Q Temperature Coefficient ±5 ppm/°C
DC Lowpass Gain Accuracy Mode 1, R1 = R2 = 10kΩ±0.1 ±0.5 %
V
OS1
DC offset of input inverter ±3 ±12.5
V
OS2
DC offset of 1st integrator ±4 ±15DC Offset Voltage (Figure 8)
V
OS3
DC offset of 2nd integrator ±4 ±30
mV
Crosstalk (Note 2) f
IN
= 10kHz -60 dB
Input: COM externally driven
V
DD
/2
- 0.5
V
DD
/2
V
DD
/2
+ 0.5
COM Voltage Range V
COM
Output: COM internally driven
V
DD
/2
- 0.2
V
DD
/2
V
DD
/2
+ 0.2
V
Input Resistance at COM R
COM
140 250 325 kΩ
Clock Feedthrough Up to 5th harmonic of f
CLK
200 μV
RMS
Noise (Note 3)
Mode 1, R1 = R2 = R3 =10kΩ, LP output,
Q = 1
60 μV
RMS
Output Voltage Swing 0.2 V
D D
- 0.2 V
Input Leakage Current at COM SHDN = GND, V
COM
= 0 to V
DD
±0.1 ±10 μA
CLOCK
Maximum Clock Frequency f
CLK
4 MHz
EXTCLK = GND, C
OSC
= 1000pF 95 135 175 kHz
Internal Oscillator Frequency
(Note 4)
f
OSC
EXTCLK = GND, C
OSC
= 100pF 1.35 MHz
Clock Input High V
DD
- 0.5 V
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
_______________________________________________________________________________________ 3
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
Clock Input Low 0.5 V
Clock Duty Cycle 50 ± 5%
SHDN AND EXTCLK
Input High V
IH
V
DD
- 0.5 V
Input Low V
IL
0.5 V
Input Leakage Current V
INPUT
= 0 to V
DD
±0.4 ±10 μA
POWER REQUIREMENTS
Supply Voltage V
DD
4.5 5.5 V
Power-Supply Current I
DD
No external load, mode 1, R1 = R3 = 50kΩ,
R2 = 10kΩ, Q = 5
3.5 4.0 mA
Shutdown Current I
SHDN
SHDN = GND 1 μA
INTERNAL OP AMPS CHARACTERISTICS
Output Short-Circuit Current ±18 mA
DC Open-Loop Gain R
L
10kΩ, C
L
50pF 130 dB
Gain Bandwidth Product GBW R
L
10kΩ, C
L
50pF 7 MHz
Slew Rate SR R
L
10kΩ, C
L
50pF 6.4 V/μs
ELECTRICAL CHARACTERISTICS—MAX7490 (continued)
(V
DD
= V
EXTCLK
= +5V; f
CLK
= 625kHz; 10kΩ || 50pF load to V
DD
/2 at LP_, BP_, and N_/HP_; V
SHDN
= V
DD
; 0.1µF from COM to
GND; 50% duty-cycle clock input; COM = V
DD
/2; T
A
= T
MIN
to T
MAX
. Typical values are at T
A
= +25°C, unless otherwise noted.)
(Note 1)

MAX7490EEE+

Mfr. #:
Manufacturer:
Maxim Integrated
Description:
Active Filter Dual Universal Switched-Cap
Lifecycle:
New from this manufacturer.
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