Dual Universal Switched-Capacitor Filters

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5

PARAMETER

SYMBOL

CONDITIONS

MIN

TYP

MAX

UNITS

POWER REQUIREMENTS

Supply Voltage

VDD

2.7

3.6

V

Power-Supply Current

IDD

No load, mode 1, R1 = R3 = 50k

Ω,

R2 = 10k

Ω, Q = 5

3.5

4.0

mA

Shutdown Current

ISHDN

SHDN = GND

1

μA

INTERNAL OP AMPS CHARACTERISTICS

Output Short-Circuit Current

±11

mA

DC Open-Loop Gain

RL

≥ 10kΩ, CL ≤ 50pF

130

dB

Gain Bandwidth Product

GBW

RL

≥ 10kΩ, CL ≤ 50pF

7

MHz

Slew Rate

SR

RL

≥ 10kΩ, CL ≤ 50pF

6

V/

μs

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 1VRMS 10kHz 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 1VRMS input signal of the other section.

Note 3: Bandwidth of noise measurement is 80kHz.

Note 4: fOSC (kHz) = 135 x 103 / COSC (COSC in pF)

ELECTRICAL CHARACTERISTICS—MAX7491 (continued)

(VDD = VEXTCLK = +3V; fCLK = 625kHz; 10kΩ || 50pF load to VDD/2 at LP_, BP_, and N_/HP_; VSHDN = VDD; 0.1µF from COM to

GND; 50% duty-cycle clock input; COM = VDD/2; TA = TMIN to TMAX. 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, VSHDN = VEXTCLK = VDD, COM = VDD/2, Mode 1, R3 = R1 = 50kΩ,

R2 = 10kΩ, Q = 5, TA = +25°C, unless otherwise noted.)

10

-60

1

10

100

2ND-ORDER BANDPASS FILTER

FREQUENCY RESPONSE

-50

FREQUENCY (kHz)

-30

-40

-10

-20

0

300

0

110

100

2ND-ORDER BANDPASS FILTER

PHASE RESPONSE

50

FREQUENCY (kHz)

100

200

150

250

VDD = +5V

fCLK = 625kHz

Q = 5

0

-0.8

100

1000

10,000

CLOCK-TO-CENTER FREQUENCY

DEVIATION vs. CLOCK FREQUENCY

-0.7

fCLK (kHz)

-0.6

-0.2

-0.3

-0.4

-0.5

-0.1

VDD = 5V

VDD = 3V