QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 626A DC ACCURATE, TUNABLE, LOW PASS FILTER DC626A-A, LTC1569-6 DC626A-B, LTC1569-7 DESCRIPTION The filter attenuation is 50dB at 1.5 times the filter cut- off and 80dB at 6 times the cutoff frequency. Thus, the LTC1569 family is an excellent choice in applications The LTC1569-6 and LTC1569-7 are monolithic 10th with demanding specifications for rejection of frequency order linear phase low pass filters. These are the first components outside the passband. With up to 300kHz sampled data filters in the industry to provide accurate cutoff, the LTC1569-7 is intended for systems needing control of the cutoff frequency without the need for an maximum bandwidth whereas the LTC1569-6 offers a external clock. Offered in the 8-lead SOIC package, the low power solution with consumption as low as 8mW LTC1569 family is tunable with a single resistor. The (fc = 4kHz). Operating from 3V to 5V supplies, the LTC1569s ease of use, accurate tuning and small LTC1569-6 and LTC1569-7 are available in the 8-pin package combined with its precision performance and SOIC package. high selectivity is practically impossible to achieve with discrete components. Its root raised cosine gain re- Design files for this circuit board are available. sponse and linear phase results in excellent lowpass Call the LTC factory. characteristics with steep selectivity ideal for use in data communication and data acquisition systems LTC is a trademark of Linear Technology Corporation Figure 1. Demo Circuit Board 626A-A Note: U1 on Demo Circuit 626A-A is an LTC1569-6. Demo Circuit 626A-B is the same as 626A-A except for an LTC1569-7 installed as U1. 1 QUICK START GUIDE FOR DEMONSTRATION CIRCUIT 626A DC ACCURATE, TUNABLE, LOW PASS FILTER Table 1. Key LTC1569 Family Electrical Characteristics PARAMETER CONDITION MIN TYP MAX V = 3V, AGND Voltage (Pin 3) = 1.11V 1.9V p-p 2.1V p-p S Output Voltage Range (Note1) V = 5V, AGND Voltage (Pin 3) = 2.0V 3.7V p-p 3.9V p-p S (The output AC voltage swings 8.0V p-p V = 5V, Pin 5 Shorted to Pin 7 S around a DC voltage equal to the (fclk 7MHz LTC11659-7) voltage on pin 3) (fclk 4MHz LTC11659-6) V = 3V S Output DC Offset V = 5V S V = 5V 15mV S V = 3V 25V/ C (-25V/C for LTC1569-7) S R = 10K, Pin 5 EXT Output DC Offset Drift V = 5V 25V/ C (-25V/C for LTC1569-7) S Shorted to Pin 7 V = 5V 75V/C S V = 3V 4.1MHz S Max Clock Frequency LTC1569-6 V = 5V 5MHz S V = 5V 5MHz S V = 3V 5MHz S V = 5V 7MHz Max Clock Frequency LTC1569-7 S V = 5V 10MHz S Minimum Clock Frequency V = 3V to 5V 1.5kHz S LTC1569-6 and LTC1569-7 V = 5V 3.0kHz S Table 2. TYPICAL F CUTOFF VARIATION VS. REXT LTC1569-6 LTC1569-7 Typical Typical Typical Typical R f R f EXT CUTOFF EXT CUTOFF f f CUTOFF CUTOFF Variation Variation 10K 128kHz 1% 10k 64kHz 1% 20.18K 64kHz 2.0% 20.18k 32kHz 2.0% 40.2K 32kHZ 3.5% 40.2k 16kHz 3.5% On DC 626A, REXT is equal to REXT1 + REXT2 (REXT1 is a 50k 10% potentiometer and REXT2 is a 3.4k 1% resistor). Maximum REXT value 81k (the frequency error for REXT > 50k can be greater than 3.5%). Note 1: In a single power supply circuit, the Output Voltage Range is maximized if the AGND voltage (on pin 3) is 0.37x V+ (1.85V for Vs=5V and 1.11V for Vs=3V). The AGND voltage range is 0.37x V+ to 0.5x V+ . 2