DC1141A-A Analog Devices

DEMO CIRCUIT 1141A/B QUICK START GUIDE LTC6930-X.XX, PRECISION DIGITALLY CONTROLLED OSCILLATORS LTC6930-4.19, LTC6930-5.00, LTC6930-7.37, LTC6930-8.00, LTC6930-8.19 32.768KHZ - 8.192MHZ DESCRIPTION Demonstration Circuit 1141A features the LTC6930- Design files for these circuit boards are available. Call the LTC factory. X.XX series family of very low power precision sili- , LTC and LT are registered trademarks of Linear Technology Corporation. con oscillators with a frequency error less than 0.09% at 25 C. For each oscillator, the user can select one of 8 frequencies between 32.768 kHz THE LTC6930-X.XX FREQUENCIES and 8.192 MHz. Based on fixed master oscillator frequency internal frequency dividers between 1 and The LTC6930-4.19 (DC1141A-A) 128 provide the 8 different frequencies. DIVC DIVB DIVA Frequency The LTC6930 requires no external components 0 0 0 4.194304MHz other than power supply bypass capacitors and op- 0 0 1 2.097152MHz erates with a single 1.7V to 5.5V supply. 0 1 0 1.048576MHz A DC1141A PCB assembly consists of a 2 inch X 2 0 1 1 524.288kHz inch buffer board with a BNC output and a DIP-8 1 0 0 262.144kHz oscillator board mounted on an 8-pin socket. The 1 0 1 131.072kHz DIP-8 oscillator board can be removed from the 1 1 0 65.536kHz buffer board and used for prototyping. 1 1 1 32.768kHz The three digitally controlled inputs of an LTC6930- X.XX (DIVA, DIVB and DIVC) can be set on a The LTC6930-5.00 (DC1141A-B) DC1141A-X with three jumblers or set externally by DIVC DIVB DIVA Frequency connecting wires to the on board turrets. 0 0 0 5.0000MHz 0 0 1 2.5000MHz The Digital Input and Divider Setting: 0 1 0 1.2500MHz DIVC DIVB DIVA DIVIDE BY 0 1 1 625.000kHz 0 0 0 1 1 0 0 312.500kHz 0 0 1 2 1 0 1 156.250kHz 0 1 0 4 1 1 0 78.1250kHz 0 1 1 8 1 1 1 39.0625kHz 1 0 0 16 1 0 1 32 The LTC6930-7.37 (DC1141A-C) 1 1 0 64 DIVC DIVB DIVA Frequency 1 1 1 128 0 0 0 7.3728MHz Note: DIVC is the MSB 0 0 1 3.6864MHz 0 1 0 1.8432MHz 0 1 1 921.6kHz There are five DC1141A boards: 1 0 0 460.8kHz 1. DC1141A-A with an LTC6930-4.19 1 0 1 230.4kHz 2. DC1141A-B with an LTC6930-5.00 1 1 0 115.2kHz 3. DC1141A-C with an LTC6930-7.37 1 1 1 57.6kHz 4. DC1141A-D with an LTC6930-8.00 5. DC1141A-E with an LTC6930-8.19 1 DC1141A QUICK START QUIDE The LTC6930-8.00 (DC1141A-D) DIVC DIVB DIVA Frequency The LTC6930-8.19 (DC1141A-E) 0 0 0 8.000MHz DIVC DIVB DIVA Frequency 0 0 1 4.000MHz 0 0 0 8.192MHz 0 1 0 2.000MHz 0 0 1 4.096MHz 0 1 1 1.000MHz 0 1 0 2.048MHz 1 0 0 500.0kHz 0 1 1 1.024MHz 1 0 1 250.0kHz 1 0 0 512.0kHz 1 1 0 125.0kHz 1 0 1 256.0kHz 1 1 1 62.5kHz 1 1 0 128.0kHz 1 1 1 64.0kHz QUICK START PROCEDURE Test Equipment: 1. A single power supply, 3V 5V. 2. An oscilloscope with at least 100MHz bandwidth. 3. A frequency counter Test Procedure: 1. On the DC1141A-X.XX board set the DIVA, DIVB and DIVC jumpers to the 0 position. 2. Set power supply for 3.00V. 3. Connect power supply as shown in Figure 1. 4. Connect the VOUT BFR (J1) of the board to an oscilloscope input terminated with 50ohms. 5. Turn on the power supply. 6. The oscilloscope should show a clean squarewave 0V to 1.375V (the LTC6930 output is 0V to 3V and is divided by two thru the on board buffer with a typical 2.75V logic high). 7. Remove the board connection to the oscilloscope and connect to a frequency counter. 8. The counters frequency should be equal to the highest LTC6930-X.XX frequency 0.9%. Highest Frequency (DIVC, DIVB, DIVA is 000) DC1141A-A 4.194304MHz DC1141A-B 5.000MHz DC1141A-C 7.3728MHz DC1141A-D 8.000MHz DC1141A-E 8.192MHz End of test. 2