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 LTC6930X.XX series family of very low power precision silicon 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 and 8.192 MHz. Based on fixed master oscillator frequency internal frequency dividers between 1 and 128 provide the 8 different frequencies. The LTC6930 requires no external components other than power supply bypass capacitors and operates with a single 1.7V to 5.5V supply. A DC1141A PCB assembly consists of a 2 inch X 2 inch buffer board with a BNC output and a DIP-8 oscillator board mounted on an 8-pin socket. The DIP-8 oscillator board can be removed from the buffer board and used for prototyping. The three digitally controlled inputs of an LTC6930X.XX (DIVA, DIVB and DIVC) can be set on a DC1141A-X with three jumblers or set externally by connecting wires to the on board turrets. The Digital Input and Divider Setting: DIVC DIVB DIVA DIVIDE BY 0 0 0 1 0 0 1 2 0 1 0 4 0 1 1 8 1 0 0 16 1 0 1 32 1 1 0 64 1 1 1 128 Note: DIVC is the MSB There are five DC1141A boards: 1. DC1141A-A with an LTC6930-4.19 2. DC1141A-B with an LTC6930-5.00 3. DC1141A-C with an LTC6930-7.37 4. DC1141A-D with an LTC6930-8.00 5. DC1141A-E with an LTC6930-8.19 Design files for these circuit boards are available. Call the LTC factory. , LTC and LT are registered trademarks of Linear Technology Corporation. THE LTC6930-X.XX FREQUENCIES The LTC6930-4.19 (DC1141A-A) DIVC DIVB DIVA Frequency 0 0 0 4.194304MHz 0 0 1 2.097152MHz 0 1 0 1.048576MHz 0 1 1 524.288kHz 1 0 0 262.144kHz 1 0 1 131.072kHz 1 1 0 65.536kHz 1 1 1 32.768kHz The LTC6930-5.00 (DC1141A-B) DIVC DIVB DIVA Frequency 0 0 0 5.0000MHz 0 0 1 2.5000MHz 0 1 0 1.2500MHz 0 1 1 625.000kHz 1 0 0 312.500kHz 1 0 1 156.250kHz 1 1 0 78.1250kHz 1 1 1 39.0625kHz The LTC6930-7.37 (DC1141A-C) DIVC DIVB DIVA Frequency 0 0 0 7.3728MHz 0 0 1 3.6864MHz 0 1 0 1.8432MHz 0 1 1 921.6kHz 1 0 0 460.8kHz 1 0 1 230.4kHz 1 1 0 115.2kHz 1 1 1 57.6kHz 1 DC1141A QUICK START QUIDE The LTC6930-8.00 (DC1141A-D) DIVC DIVB DIVA Frequency 0 0 0 8.000MHz 0 0 1 4.000MHz 0 1 0 2.000MHz 0 1 1 1.000MHz 1 0 0 500.0kHz 1 0 1 250.0kHz 1 1 0 125.0kHz 1 1 1 62.5kHz The LTC6930-8.19 (DC1141A-E) DIVC DIVB DIVA Frequency 0 0 0 8.192MHz 0 0 1 4.096MHz 0 1 0 2.048MHz 0 1 1 1.024MHz 1 0 0 512.0kHz 1 0 1 256.0kHz 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. 2. 3. 4. 5. 6. On the DC1141A-X.XX board set the DIVA, DIVB and DIVC jumpers to the "0" position. Set power supply for 3.00V. Connect power supply as shown in Figure 1. Connect the VOUT BFR (J1) of the board to an oscilloscope input terminated with 50ohms. Turn on the power supply. 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 counter's 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 DC1141A QUICK START GUIDE Figure 1. Quick Test Set-Up Power Supply 3.00V + DIVA, DIVB, DIV C 000 100MHz Oscilloscope 50ohm input 000000 50ohm input Frequency Counter Connect board to oscilloscope or counter with a 50ohm BNC to BNC cable 3ft 3 DC1141A QUICK START QUIDE 4 DC1141A QUICK START GUIDE 5