19-1821; Rev 0; 11/00
5th-Order, Lowpass,
Switched-Capacitor Filters
General Description
The MAX7418–MAX7425 5th-order, low-pass, switched-
capacitor filters (SCFs) operate from a single +5V
(MAX7418–MAX7421) or +3V (MAX7422–MAX7425)
supply. These devices draw only 3mA of supply current
and allow corner frequencies from 1Hz to 45kHz, mak-
ing them ideal for low-power post-DAC filtering and anti-
aliasing applications. They feature a shutdown mode
that reduces supply current to 0.2µA.
Two clocking options are available: self-clocking
(through the use of an external capacitor), or external
clocking for tighter corner-frequency control. An offset
adjust pin allows for adjustment of the DC output level.
The MAX7418/MAX7422 deliver 53dB of stopband
rejection and a sharp rolloff with a 1.6 transition ratio.
The MAX7421/MAX7425 achieve a sharper rolloff with a
1.25 transition ratio while still providing 37dB of stop-
band rejection. The MAX7419/MAX7423 Bessel filters
provide low overshoot and fast settling, and the
MAX7420/MAX7424 Butterworth filters provide a maxi-
mally flat passband response. Their fixed response sim-
plifies the design task of selecting a clock frequency.
Features
o
5th-Order, Lowpass Filters
Elliptic Response (MAX7418/MAX7421/
MAX7422/MAX7425)
Bessel Response (MAX7419/MAX7423)
Butterworth Response (MAX7420/MAX7424)
o
Clock-Turnable Corner Frequency (1Hz to 45kHz)
o
Single-Supply Operation
+5V (MAX7418–MAX7421)
+3V (MAX7422–MAX7425)
o
Low Power
3mA (Operating Mode)
0.2µA (Shutdown Mode)
o
Available in 8-Pin µMAX Package
o
Low Output Offset: ±4mV
MAX7418–MAX7425
Ordering Information
PART
MAX7418CUA
MAX7418EUA
MAX7419CUA
MAX7419EUA
MAX7420CUA
MAX7420EUA
MAX7421CUA
MAX7421EUA
TEMP. RANGE
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
0°C to +70°C
-40°C to +85°C
PIN-PACKAGE
8 µMAX
8 µMAX
8 µMAX
8 µMAX
8 µMAX
8 µMAX
8 µMAX
8 µMAX
Applications
ADC Anti-Aliasing
DAC Postfiltering
CT2 Base Stations
Speech Processing
Selector Guide
PART
MAX7418
MAX7419
MAX7420
MAX7421
FILTER RESPONSE
r = 1.6
Bessel
Butterworth
r = 1.25
OPERATING
VOLTAGE (V)
+5
+5
+5
+5
Ordering Information continued at end of data sheet.
Typical Operating Circuit
V
SUPPLY
Selector Guide continued at end of data sheet.
Pin Configuration
TOP VIEW
0.1µF
V
DD
INPUT
IN
SHDN
OUT
OUTPUT
COM
IN
GND
1
2
3
8
7
CLK
SHDN
OS
OUT
CLOCK
CLK
MAX7418–
MAX7425
COM
GND
OS
0.1µF
MAX7418–
MAX7425
6
5
V
DD
4
µMAX
________________________________________________________________
Maxim Integrated Products
1
For price, delivery, and to place orders, please contact Maxim Distribution at 1-888-629-4642,
or visit Maxim’s website at www.maxim-ic.com.
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