MAX7490EEE ,Dual Universal Switched-Capacitor FiltersFeaturesThe MAX7490/MAX7491 consist of two identical low- Dual 2nd-Order Filter in a 16-Pin QSOP P ..
MAX7490EEE+ ,Dual Universal Switched-Capacitor FiltersFeaturesThe MAX7490/MAX7491 consist of two identical low-♦ Dual 2nd-Order Filter in a 16-Pin QSOP P ..
MAX7490EEE+ ,Dual Universal Switched-Capacitor FiltersApplicationsPIN-PART TEMP RANGE VOLTAGETunable Active FiltersPACKAGE(+V)Multipole FiltersMAX7490CEE ..
MAX7491 ,Dual Universal Switched-Capacitor FiltersApplicationsPIN-PART TEMP RANGE VOLTAGETunable Active FiltersPACKAGE(+V)Multipole FiltersMAX7490CEE ..
MAX7491EEE ,Dual Universal Switched-Capacitor FiltersFeaturesThe MAX7490/MAX7491 consist of two identical low- Dual 2nd-Order Filter in a 16-Pin QSOP P ..
MAX7491EEE+ ,Dual Universal Switched-Capacitor FiltersELECTRICAL CHARACTERISTICS—MAX7490(V = V = +5V; f = 625kHz; 10kΩ || 50pF load to V /2 at LP_, BP_, ..
MB6M ,MINIATURE GLASS PASSIVATED SINGLE-PHASE BRIDGE RECTIFIERThermal Characteristics (TA = 25°C unless otherwise noted)Parameter Symbol MB2M MB4M MB6M UnitDevic ..
MB6S ,Bridge RectifiersThermal Characteristics (T = 25°C unless otherwise noted)AParameter Symbol MB2S MB4S MB6S UnitDevic ..
MB7117E , Schottky TTL 2048-Bit Bipolar Programmable Read-Only Memory
MB71A38-25 , PROGRAMMABLE SCHOTTKY 16384-BIT READ ONLY MEMORY
MAX7490EEE
Dual Universal Switched-Capacitor Filters
General DescriptionThe 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.
________________________ApplicationsTunable Active Filters
Multipole Filters
ADC Anti-Aliasing
Post-DAC Filtering
Adaptive Filtering
Phase-Locked Loops (PLLs)
Set-Top Boxes
FeaturesDual 2nd-Order Filter in a 16-Pin QSOP PackageHigh AccuracyAccuracy: ±0.2%
Clock-to-Center Frequency Error: ±0.2%Rail-to-Rail Input and Output OperationSingle-Supply Operation: +5V (MAX7490)
or +3V (MAX7491)Internal or External ClockHighpass, Lowpass, Bandpass, and Notch FiltersClock-to-Center Frequency Ratio of 100:1Internal Sampling-to-Center Frequency Ratio
of 200:1Center Frequency up to 40kHzEasily Cascaded for Multipole FiltersLow-Power Shutdown: <1µA Supply Current
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
Pin Configuration19-1768; Rev 0; 7/00
Ordering InformationRail-to-Rail is a registered trademark of Nippon Motorola, Ltd.
Typical Application Circuit appears at end of data sheet.
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS—MAX7490(VDD= EXTCLK = +5V, fCLK = 625kHz, TA= TMINto TMAX, 10kΩ|| 50pF load to VDD/2 at LP_, BP_, and N_/HP_, SHDN= VDD, 0.1µF
from COM to GND, 50% duty-cycle clock input, COM = VDD/2. Typical values are at TA= +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.
VDDto GND..............................................................-0.3V to +6V
EXTCLK, SHDNto GND...........................................-0.3V to +6V
INV_, LP_, BP_, N_/HP_, S_, COM,
CLK to GND............................................-0.3V to (VDD+ 0.3V)
Maximum Current into Any Pin ...........................................50mA
Continuous Power Dissipation (TA= +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
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
ELECTRICAL CHARACTERISTICS—MAX7490 (continued)(VDD= EXTCLK = +5V, fCLK = 625kHz, TA= TMINto TMAX, 10kΩ|| 50pF load to VDD/2 at LP_, BP_, and N_/HP_, SHDN= VDD, 0.1µF
from COM to GND, 50% duty-cycle clock input, COM = VDD/2. Typical values are at TA= +25°C, unless otherwise noted.) (Note 1)
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
ELECTRICAL CHARACTERISTICS—MAX7491(VDD= EXTCLK = +3V, fCLK = 625kHz, TA= TMINto TMAX, 10kΩ|| 50pF load to VDD/2 at LP_, BP_, and N_/HP_, SHDN= VDD, 0.1µF
from COM to GND, 50% duty-cycle clock input, COM = VDD/2. Typical values are at TA= +25°C, unless otherwise noted.) (Note 1)
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
Note 1:Resistive loading of the N_/HP_, LP_, BP_ outputs includes the resistors used for the filter implementation.
Note 2:Crosstalk between internal filter sections is measured by applying a 1VRMS10kHz signal to one bandpass filter section input
and grounding the input of the other bandpass filter section. The crosstalk is the ratio between the output of the grounded
filter section and the 1VRMSinput signal of the other section.
Note 3:Bandwidth of noise measurement is 80kHz.
Note 4:fOSC(kHz) = 135 x 103/ COSC(COSCin pF)
ELECTRICAL CHARACTERISTICS—MAX7491 (continued)(VDD= EXTCLK = +3V, fCLK = 625kHz, TA= TMINto TMAX, 10kΩ|| 50pF load to VDD/2 at LP_, BP_, and N_/HP_, SHDN= VDD, 0.1µF
from COM to GND, 50% duty-cycle clock input, COM = VDD/2. Typical values are at TA= +25°C, unless otherwise noted.) (Note 1)
Typical Operating Characteristics(VDD= +5V for MAX7490, VDD= +3V for MAX7491, fCLK= 625kHz, SHDN= EXTCLK = VDD, COM = VDD/2, Mode 1, R3 = R1 = 50kΩ,
R2 = 10kΩ, Q = 5, TA= +25°C, unless otherwise noted.)
MAX7490/MAX7491
Dual Universal Switched-Capacitor FiltersfCLK/fO DEVIATION vs. Q
MAX7490-04
fCLK
DEVIATION (%)
fCLK/fO DEVIATION vs. TEMPERATURE
MAX7490-05
TEMPERATURE (°C)
fCLK
DEVIATION (%)
100100010,000
Q DEVIATION vs. fCLKMAX7490-06
fCLK (kHz)
Q DEVIATION (%)
Q DEVIATION vs. TEMPERATURE
MAX7490-07
TEMPERATURE (°C)
DEVIATION (%)
NOISE vs. Q
MAX7490-08
NOISE (µV
RMS
SUPPLY CURRENT vs. TEMPERATURE
MAX7490-09
TEMPERATURE (°C)
IDD
(mA)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7490-10
VDD (V)
IDD
(mA)
SUPPLY CURRENT vs. SUPPLY VOLTAGE
MAX7490-11
VDD (V)
IDD
(mA)
-12010k
MAX7491
THD + NOISE vs. FREQUENCYMAX7490-12
INPUT FREQUENCY (Hz)
THD + NOISE (dB)
Typical Operating Characteristics (continued)
(VDD= +5V for MAX7490, VDD= +3V for MAX7491, fCLK= 625kHz, SHDN= EXTCLK = VDD, COM = VDD/2, Mode 1, R3 = R1 = 50kΩ,
R2 = 10kΩ, Q = 5, TA= +25°C, unless otherwise noted.)
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters-12010k
MAX7490
THD + NOISE vs. FREQUENCYMAX7490-13
INPUT FREQUENCY (Hz)
THD + NOISE (dB)
MAX7491
THD + NOISE vs. INPUT VOLTAGE
MAX7490-14
INPUT VOLTAGE (Vp-p)
THD + NOISE (dB)
MAX7490
THD + NOISE vs. INPUT VOLTAGE
MAX7490-15
INPUT VOLTAGE (Vp-p)
THD + NOISE (dB)
OUTPUT VOLTAGE SWING vs. RLOAD
MAX7490-16
RLOAD (kΩ) TO COM
OUTPUT SWING (Vp-p)
INTERNAL OSCILLATOR PERIOD
vs. SMALL CAPACITANCE
MAX7490-17
CAPACITANCE (pF)
INTERNAL OSCILLATOR FREQUENCY (kHz)
INTERNAL OSCILLATOR PERIOD
vs. LARGE CAPACITANCE
MAX7490-18
CAPACITANCE (nF)
INTERNAL OSCILLATOR FREQUENCY (kHz)
INTERNAL OSCILLATOR FREQUENCY
vs. SUPPLY VOLTAGE
MAX7490-19
VDD (V)
INTERNAL OSCILLATOR FREQUENCY (kHz)
INTERNAL OSCILLATOR FREQUENCY
vs. TEMPERATURE
MAX7490-20
TEMPERATURE (°C)
INTERNAL OSCILLATOR FREQUENCY (kHz)
Typical Operating Characteristics (continued)(VDD= +5V for MAX7490, VDD= +3V for MAX7491, fCLK= 625kHz, SHDN= EXTCLK = VDD, COM = VDD/2, Mode 1, R3 = R1 = 50kΩ,
R2 = 10kΩ, Q = 5, TA= +25°C, unless otherwise noted.)
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
_______________Detailed DescriptionThe MAX7490/MAX7491 are universal switched-capaci-
tor filters designed with a fixed internal fCLK/fOratio of
100:1. Operating modes use external resistors connect-
ed in different arrangements to realize different filter
functions (highpass, lowpass, bandpass, notch) in all of
the classical filter topologies (Butterworth, Bessel, ellip-
tic, Chebyshev). Figure 1 shows a block diagram.
Clock Signal
External ClockThe MAX7490/MAX7491 switched-capacitor filters are
designed for use with external clocks that have a 50%
±5% duty cycle. When using an external clock, drive
the EXTCLK pin high or connect to VDD. Drive CLK with
CMOS logic levels (GND and VDD). Varying the rate of
the external clock adjusts the center frequency of the
filter:= fCLK /100
Internal ClockWhen using the internal oscillator, drive the EXTCLK pin
low or connect to GND and connect a capacitor (COSC)
between CLK and GND. The value of the capacitor
(COSC) determines the oscillator frequency as follows:
fOSC(kHz) = 135 x 103/ COSC(pF)
Since COSCis in the low picofarads, minimize the stray
capacitance at CLK so that it does not affect the inter-
nal oscillator frequency. Varying the frequency of the
internal oscillator adjusts the filter’s center frequency by
a 100:1 clock-to-center frequency ratio. For example,
an internal oscillator frequency of 135kHz produces a
nominal center frequency of 1.35kHz.
MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
2nd-Order Filter StageThe MAX7490/MAX7491 are dual biquad filters. The
biquad topology allows the use of standard filter tables
and equations to implement simultaneous lowpass,
bandpass, and notch or highpass filters. Topologies
such as Butterworth, Chebyshev, Bessel, elliptic, as
well as custom algorithms are possible.
Internal Common VoltageThe COM pin sets the common-mode input voltage and
is internally biased to VDD/2with a resistor-divider. The
resistors used are typically 250kΩfor the MAX7490,
and typically 80kΩfor the MAX7491. The common-
mode voltage is easily overdriven by an external volt-
age supply if desired. The COM pin should be
bypassed to the analog ground with at least a 0.1µF
capacitor.
Inverting InputsLocate resistors that are connected to INV_ as close as
possible to INV_ to reduce stray capacitance and noise
pickup. INV_ are inverting inputs to continuous-time op
amps, and behave like a virtual ground. There is no
sampling energy present on these inputs.
OutputsEach switched-capacitor section, together with two to
four external resistors, can generate all standard 2nd-
order functions: bandpass, lowpass, highpass, and
notch (band-reject) functions. Three of these functions
are simultaneously available. The maximum signal
swing is limited by the power-supply voltages used.
The amplifiers’ outputs in the MAX7490/MAX7491 are
able to swing to within approximately 0.2V of either
supply.
Driving coaxial cable, large capacitive loads, or total
resistive loads less than 10kΩwill degrade the total
harmonic distortion (THD) performance. Note that the
effective resistive load at the output must include both
the feedback resistors and any external load resistors.
Low-Power Shutdown ModeThe MAX7490/MAX7491 have a shutdown mode that is
activated by driving SHDNlow. In shutdown mode, the
filter supply current reduces to <1µA (max), and the fil-
ter outputs become high impedance. The COM input
also becomes high impedance during shutdown. For
normal operation, drive SHDNhigh or connect to VDD.
__________Applications InformationDesigning with the MAX7490/MAX7491 begins by
selecting the mode that best fits the desired circuit
requirements. Table 1 lists the available modes and
their relative advantages and disadvantages. Table 2
lists the different nomenclature used in the explanations
that follow.
Mode 1Figure 2 shows the MAX7490/MAX7491s’ configuration
of Mode 1. This mode provides 2nd-order notch, low-
pass, and bandpass filter functions. The gain at all
three outputs is inversely proportional to the value of
R1. The center frequency, fO, is fixed at fCLK/100. High-
Q bandpass filters can be built without exceeding the
bandpass amplifier’s output swing (i.e., HOBPdoes not
