MAX7426/MAX7427 19-1710 Rev 0 4/00 5th-Order, Lowpass, Elliptic, Switched-Capacitor Filters General Description Features The MAX7426/MAX7427 5th-order, lowpass, elliptic, 5th-Order, Elliptic Lowpass Filters switched-capacitor filters (SCFs) operate from a single Low Noise and Distortion: -80dB THD + Noise +5V (MAX7426) or +3V (MAX7427) supply. The devices draw only 0.8mA of supply current and allow corner fre- Clock-Tunable Corner Frequency (1Hz to 12kHz) quencies from 1Hz to 12kHz, making them ideal for Single-Supply Operation low-power post-DAC filtering and anti-aliasing applica- tions. They can be put into a low-power mode, reducing +5V (MAX7426) supply current to 0.2A. +3V (MAX7427) Two clocking options are available: self-clocking (through Low Power the use of an external capacitor) or external clocking for 0.8mA (Operating Mode) tighter cutoff-frequency control. An offset-adjust pin 0.2A (Shutdown Mode) allows for adjustment of the DC output level. The MAX7426/MAX7427 deliver 37dB of stopband Available in 8-Pin MAX/PDIP Packages rejection and a sharp rolloff with a transition ratio of Low Output Offset: 4mV 1.25. Their fixed response limits the design task to selecting a clock frequency. Applications Ordering Information ADC Anti-Aliasing CT2 Base Stations PART TEMP. RANGE PIN-PACKAGE MAX7426CUA 0C to +70C 8 MAX Post-DAC Filtering Speech Processing MAX7426CPA 0C to +70C 8 Plastic DIP MAX7426EUA -40C to +85C 8 MAX MAX7426EPA -40C to +85C 8 Plastic DIP MAX7427CUA 0C to +70C 8 MAX Selector Guide MAX7427CPA 0C to +70C 8 Plastic DIP MAX7427EUA -40C to +85C 8 MAX OPERATING PART TRANSITION RATIO VOLTAGE (V) MAX7427EPA -40C to +85C 8 Plastic DIP MAX7426 r = 1.25 +5 MAX7427 r = 1.25 +3 Pin Configuration Typical Operating Circuit V SUPPLY TOP VIEW 0.1 F V COM 1 8 CLK DD SHDN INPUT IN OUT OUTPUT IN 2 7 SHDN MAX7426 GND 3 MAX7427 6 OS MAX7426 MAX7427 V 4 5 OUT DD CLOCK CLK COM 0.1 F OS GND MAX/PDIP Maxim Integrated Products 1 For free samples and the latest literature, visit www.maxim-ic.com or phone 1-800-998-8800. For small orders, phone 1-800-835-8769.5th-Order, Lowpass, Elliptic, Switched-Capacitor Filters ABSOLUTE MAXIMUM RATINGS V to GND..............................................................-0.3V to +6V Operating Temperature Ranges DD IN, OUT, COM, OS, CLK, SHDN ................-0.3V to (V + 0.3V) MAX742 C A....................................................0C to +70C DD OUT Short-Circuit Duration.......................................................1s MAX742 E A .................................................-40C to +85C Continuous Power Dissipation (T = +70C) Storage Temperature Range .............................-65C to +160C A 8-Pin MAX (derate 4.1mW/C above +70C) .............330mW Lead Temperature (soldering, 10s) .................................+300C 8-Pin PDIP (derate 6.90mW/C above +70C).............552mW 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. ELECTRICAL CHARACTERISTICSMAX7426 (V = +5V, filter output measured at OUT, 10k 50pF load to GND at OUT, SHDN = V , OS = COM, 0.1F from COM to GND, DD DD f = 100kHz, T = T to T , unless otherwise noted. Typical values are at T = +25C.) CLK A MIN MAX A PARAMETER SYMBOL CONDITIONS MIN TYP MAX UNITS FILTER Corner-Frequency Range f (Note 1) 0.001 to 9 kHz C Clock-to-Corner Ratio f /f 100:1 CLK C Clock-to-Corner Tempco 10 ppm/C Output Voltage Range 0.25 V - 0.25 V DD Output Offset Voltage V V = V = V / 2 4 25 mV OFFSET IN COM DD DC Insertion Gain with Output V = V / 2 (Note 2) 0 0.2 0.4 dB COM DD Offset Removed Total Harmonic Distortion plus f = 200Hz, V = 4Vp-p, IN IN THD+N -81 dB Noise measurement bandwidth = 22kHz Offset Voltage Gain A OS to OUT +1 V/V OS V V V DD DD DD Input, COM externally driven - 0.5 + 0.5 2 2 2 COM Voltage Range V V COM V V V DD DD DD Output, COM internally driven - 0.2 + 0.2 2 2 2 Input Voltage Range at OS V Measured with respect to COM 0.1 V OS Input Resistance at COM R 90 130 k COM Clock Feedthrough T = +25C 5 mVp-p A Resistive Output Load Drive R 10 1 k L Maximum Capacitive Load C 50 500 pF L at OUT Input Leakage Current at COM SHDN = GND, V = 0 to V 0.2 10 A COM DD Input Leakage Current at OS V = 0 to V 0.2 10 A OS DD CLOCK Internal Oscillator Frequency f C = 1000pF (Note 3) 13.5 17.5 21.5 kHz OSC OSC Clock Output Current I 8 12.5 A CLK (internal oscillator mode) Clock Input High V 4.5 V IH Clock Input Low V 0.5 V IL 2 MAX7426/MAX7427