Datasheet

MAX7490/MAX7491
Dual Universal Switched-Capacitor Filters
_______________________________________________________________________________________ 5
PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS
POWER REQUIREMENTS
Supply Voltage V
DD
2.7 3.6 V
Power-Supply Current I
DD
No 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 ±11 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 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 1V
RMS
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 1V
RMS
input signal of the other section.
Note 3: Bandwidth of noise measurement is 80kHz.
Note 4: f
OSC
(kHz) = 135 x 10
3
/ C
OSC
(C
OSC
in pF)
ELECTRICAL CHARACTERISTICS—MAX7491 (continued)
(V
DD
= V
EXTCLK
= +3V; 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)
Typical Operating Characteristics
(V
DD
= +5V for MAX7490, V
DD
= +3V for MAX7491, f
CLK
= 625kHz, V
SHDN
= V
EXTCLK
= V
DD
, COM = V
DD
/2, Mode 1, R3 = R1 = 50kΩ,
R2 = 10kΩ, Q = 5, T
A
= +25°C, unless otherwise noted.)
10
-60
1 10 100
2ND-ORDER BANDPASS FILTER
FREQUENCY RESPONSE
-50
MAX7490-01
FREQUENCY (kHz)
GAIN (dB)
-30
-40
-10
-20
0
300
0
110100
2ND-ORDER BANDPASS FILTER
PHASE RESPONSE
50
MAX7490-02
FREQUENCY (kHz)
PHASE (%)
100
200
150
250
V
DD
= +5V
f
CLK
= 625kHz
Q
= 5
0
-0.8
100 1000 10,000
CLOCK-TO-CENTER FREQUENCY
DEVIATION vs. CLOCK FREQUENCY
-0.7
MAX7490-03
f
CLK
(kHz)
f
CLK
/f
O
DEVIATION (%)
-0.6
-0.2
-0.3
-0.4
-0.5
-0.1
V
DD
= 5V
V
DD
= 3V