19-1821; Rev 0; 11/00
MAX7418–MAX7425
5th-Order, Lowpass, Switched-Capacitor Filters
General Description
The MAX7418–MAX7425 5th-order, low-pass, switchedcapacitor 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, making them ideal for low-power post-DAC filtering and antialiasing 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 stopband rejection. The MAX7419/MAX7423 Bessel filters provide low overshoot and fast settling, and the MAX7420/MAX7424 Butterworth filters provide a maximally flat passband response. Their fixed response simplifies the design task of selecting a clock frequency.
Applications
ADC Anti-Aliasing DAC Postfiltering
CT2 Base Stations Speech Processing
Selector Guide
PART
FILTER RESPONSE
OPERATING VOLTAGE (V)
MAX7418
r = 1. 6
+5
MAX7419
Bessel
+5
MAX7420
Butterworth
+5
MAX7421
r = 1. 25
+5
Selector Guide continued at end of data sheet.
Pin Configuration
TOP VIEW
COM 1 IN 2
GND 3 VDD 4
MAX7418– MAX7425
8 CLK 7 SHDN 6 OS 5 OUT
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
Ordering Informatio...