DC266B-B

DEMO MANUAL DC266B LTC1562/LTC1562-2 Quad 2nd Order Active RC Filter IC Description Demonstration circuit DC266B-A is for the evaluation of For other possible LTC1562 or LTC1562-2 configurations, 8th order filter circuits using an LTC1562 (no dash) and the DC226B-A and DC226B-B have unused pads for 0805 DC266B-B for an LTC1562-2. LTC1562 and LTC1562-2 surface mount resistors and capacitors preconfigured are quad 2nd order active-RC filter building blocks. The with PCB traces to allow for the following filter circuits: LTC1562 or LTC1562-2 2nd order sections can be con- 1. 8th order lowpass filter figured with external resistors to implement lowpass and 2. Dual 4th or 5th order lowpass filter narrow or wide band bandpass filters. The frequency range for a lowpass filter is 10kHz to 150kHz and 20kHz to 3. 8th order narrow band bandpass 300kHz for the LTC1562 and LTC1562-2 respectively. The 4. 8th order wide band bandpass. frequency range for a bandpass filter is 20kHz to 120kHz and 40kHz to 250kHz for the LTC1562 and LTC1562-2 Refer to the LTC1562 or LTC1562-2 data sheet for com- respectively (the LTC1562A is higher precision version prehensive filter design information. of the LTC1562). Design files for this circuit board are available at For testing and evaluation, the DC266B-A is configured as DEMO MANUAL DC266B Quick s tart p D See Figure 1 for proper measurement equipment setup 6. Connect an oscilloscope channel to OUT. and follow the procedure below. 7. For a DC266B-A, set the scaling of an oscilloscope to 1. Set SW1 to DUAL. 1V/20s per division. 2. With power off, connect a dual 5V power supply to +V For a DC266B-B, set the scaling of an oscilloscope to and V. 1V/5s per division. 3. Connect a function generator to IN. 8. Power up the system and the oscilloscope should show 2V sine wave. P-P 4. For a DC266B-A, set the function generator to a 2V , P-P 50kHz, sine wave. 9. To test stopband attenuation of DC266B-A, set the input frequency to 25kHz or 75kHz. 5. For a DC266B-B, set the function generator to a 2V , P-P 200kHz, sine wave. 10. To test stopband attenuation of DC266B-B, set the input frequency to 150kHz or 250kHz. Figure 1. Quick Start Test Equipment Setup dc266bf 2 ure roce