General Description
The MAX7426/MAX7427 5th-order, lowpass, elliptic,
switched-capacitor filters (SCFs) operate from a single
+5V (MAX7426) or +3V (MAX7427) supply. The devices
draw only 0.8mA of supply current and allow corner fre-
quencies from 1Hz to 12kHz, making them ideal for
low-power post-DAC filtering and anti-aliasing applica-
tions. They can be put into a low-power mode, reducing
supply current to 0.2µA.
Two clocking options are available: self-clocking (through
the use of an external capacitor) or external clocking for
tighter cutoff-frequency control. An offset-adjust pin
allows for adjustment of the DC output level.
The MAX7426/MAX7427 deliver 37dB of stopband
rejection and a sharp rolloff with a transition ratio of
1.25. Their fixed response limits the design task to
selecting a clock frequency.
Applications
ADC Anti-Aliasing CT2 Base Stations
Post-DAC Filtering Speech Processing
Features
5th-Order, Elliptic Lowpass Filters
Low Noise and Distortion: -80dB THD + Noise
Clock-Tunable Corner Frequency (1Hz to 12kHz)
Single-Supply Operation
+5V (MAX7426)
+3V (MAX7427)
Low Power
0.8mA (Operating Mode)
0.2µA (Shutdown Mode)
Available in 8-Pin µMAX/PDIP Packages
Low Output Offset: ±4mV
MAX7426/MAX7427
5th-Order, Lowpass, Elliptic,
Switched-Capacitor Filters
________________________________________________________________ Maxim Integrated Products 1
OS
OUTV
DD
1
2
8
7
CLK
SHDNIN
GND
COM
µMAX/PDIP
TOP VIEW
3
4
6
5
MAX7426
MAX7427
V
DD
IN
CLK
OUT
GND
INPUT
0.1µF
0.1µF
CLOCK
SHDN
OUTPUT
COM
OS
MAX7426
MAX7427
V
SUPPLY
Typical Operating Circuit
19-1710; Rev 0; 4/00
Pin Configuration
Ordering Information
PART
MAX7426CUA
MAX7426CPA
MAX7426EUA -40°C to +85°C
0°C to +70°C
0°C to +70°C
TEMP. RANGE PIN-PACKAGE
8 µMAX
8 Plastic DIP
8 µMAX
MAX7426EPA -40°C to +85°C 8 Plastic DIP
PART
TRANSITION RATIO
OPERATING
VOLTAGE (V)
MAX7426 r = 1.25 +5
Selector Guide
MAX7427 r = 1.25 +3
MAX7427CUA
MAX7427CPA
MAX7427EUA -40°C to +85°C
0°C to +70°C
0°C to +70°C 8 µMAX
8 Plastic DIP
8 µMAX
MAX7427EPA -40°C to +85°C 8 Plastic DIP
For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800.
For small orders, phone 1-800-835-8769.
MAX7426/MAX7427
5th-Order, Lowpass, Elliptic,
Switched-Capacitor Filters
2 _______________________________________________________________________________________
ABSOLUTE MAXIMUM RATINGS
ELECTRICAL CHARACTERISTICS—MAX7426
(V
DD
= +5V, filter output measured at OUT, 10k
|| 50pF load to GND at OUT, SHDN = V
DD
, OS = COM, 0.1µF from COM to GND,
f
CLK
= 100kHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
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
IN, OUT, COM, OS, CLK, SHDN ................-0.3V to (V
DD
+ 0.3V)
OUT Short-Circuit Duration.......................................................1s
Continuous Power Dissipation (T
A
= +70°C)
8-Pin µMAX (derate 4.1mW/°C above +70°C) .............330mW
8-Pin PDIP (derate 6.90mW/°C above +70°C).............552mW
Operating Temperature Ranges
MAX742 _C_A....................................................0°C to +70°C
MAX742 _E_A .................................................-40°C to +85°C
Storage Temperature Range .............................-65°C to +160°C
Lead Temperature (soldering, 10s) .................................+300°C
C
OSC
= 1000pF (Note 3)
V
OS
= 0 to V
DD
SHDN = GND, V
COM
= 0 to V
DD
(Note 1)
T
A
= +25°C
Input, COM externally driven
OS to OUT
Measured with respect to COM
f
IN
= 200Hz, V
IN
= 4Vp-p,
measurement bandwidth = 22kHz
V
IN
= V
COM
= V
DD
/ 2
V
COM
= V
DD
/ 2 (Note 2)
Output, COM internally driven
CONDITIONS
13.5 17.5 21.5f
OSC
Internal Oscillator Frequency
±0.2 ±10Input Leakage Current at OS
±0.2 ±10Input Leakage Current at COM
50 500C
L
10 1R
L
Resistive Output Load Drive
5Clock Feedthrough
90 130R
COM
Input Resistance at COM
±0.1V
OS
Input Voltage Range at OS
V
DD
- 0.2
V
DD
V
DD
+ 0.2
2 2 2
100:1f
CLK
/f
C
Clock-to-Corner Ratio
0.001 to 9f
C
Corner-Frequency Range
V
DD
- 0.5
V
DD
V
DD
+ 0.5
2 2 2
V
COM
COM Voltage Range
+1A
OS
Offset Voltage Gain
-81THD+N
Total Harmonic Distortion plus
Noise
10Clock-to-Corner Tempco
0.25 V
DD
- 0.25Output Voltage Range
±4 ±25V
OFFSET
Output Offset Voltage
0 0.2 0.4
DC Insertion Gain with Output
Offset Removed
MIN TYP MAXSYMBOLPARAMETER
0.5V
IL
Clock Input Low
4.5V
IH
Clock Input High
±8 ±12.5I
CLK
Clock Output Current
(internal oscillator mode)
V
V
µA
kHz
µA
µA
pF
k
mVp-p
k
V
V
V/V
dB
dB
mV
V
ppm/°C
kHz
UNITS
Maximum Capacitive Load
at OUT
FILTER
CLOCK
MAX7426/MAX7427
5th-Order, Lowpass, Elliptic,
Switched-Capacitor Filters
_______________________________________________________________________________________ 3
5th-Order, Lowpass, Elliptic,
Switched-Capacitor Filters
ELECTRICAL CHARACTERISTICS—MAX7426 (continued)
(V
DD
= +5V, filter output measured at OUT, 10k
|| 50pF load to GND at OUT, SHDN = V
DD
, OS = COM, 0.1µF from COM to GND,
f
CLK
= 100kHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
ELECTRICAL CHARACTERISTICS—MAX7427
(V
DD
= +3V, filter output measured at OUT pin, 10k || 50pF load to GND at OUT, SHDN = V
DD
, OS = COM, 0.1µF from COM to
GND, f
CLK
= 100kHz, T
A
= T
MIN
to T
MAX
, unless otherwise noted. Typical values are at T
A
= +25°C.)
CONDITIONS
MIN TYP MAXSYMBOLPARAMETER
Measured at DC
SHDN = GND
Operating mode, no load
0.5V
SDL
SHDN Input Low
4.5V
SDH
SHDN Input High
70PSRRPower-Supply Rejection Ratio
0.2 1I
SHDN
Shutdown Current
0.8 1.0Supply Current I
DD
4.5 5.5V
DD
Supply Voltage
V
V
dB
µA
mA
V
UNITS
SHDN Input Leakage Current
V
SHDN
= 0 to V
DD
±0.2 ±10 µA
V
OS
Input Voltage Range at OS
90 130R
COM
Input Resistance at COM k
(Note 1)
T
A
= +25°C
Measured with respect to COM
OS to OUT
f
IN
= 200Hz, V
IN
= 2.5Vp-p,
measurement bandwidth = 22kHz
V
IN
= V
COM
= V
DD
/ 2
V
COM
= V
DD
/ 2 (Note 2)
CONDITIONS
50 500C
L
10 1R
L
Resistance Output Load Drive
3Clock Feedthrough
±0.1
V
DD
- 0.1
V
DD
V
DD
+ 0.1
2 2 2
V
COM
COM Voltage Range
100:1f
CLK
/
f
C
Clock-to-Corner Ratio
0.001 to 12f
C
Corner-Frequency Range
+1A
OS
Offset Voltage Gain
-79THD+N
Total Harmonic Distortion plus
Noise
10Clock-to-Corner Tempco
0.25 V
DD
- 0.25Output Voltage Range
±4 ±25V
OFFSET
Output Offset Voltage
0 0.2 0.4
DC Insertion Gain with Output
Offset Removed
MIN TYP MAXSYMBOLPARAMETER
pF
k
mVp-p
V
V
V/V
dB
dB
mV
V
ppm/°C
kHz
UNITS
Maximum Capacitive Load
at OUT
Input Leakage Current at COM
SHDN = GND, V
COM
= 0 to V
DD
±0.2 ±10 µA
Input Leakage Current at OS V
OS
= 0 to V
DD
±0.2 ±10 µA
POWER REQUIREMENTS
SHUTDOWN
FILTER CHARACTERISTICS

MAX7426CUA+

Mfr. #:
Manufacturer:
Maxim Integrated
Description:
Active Filter 5th-Order Lowpass Elliptic Filter
Lifecycle:
New from this manufacturer.
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