Electronic Components Datasheet Search |
|
AD654JNZ Datasheet(PDF) 9 Page - Analog Devices |
|
AD654JNZ Datasheet(HTML) 9 Page - Analog Devices |
9 / 12 page AD654 REV. –9– 8 7 6 5 1 2 3 4 AD654 1k VIN (0V TO 1V) 1000pF 5V 10k 825 1% 500 A D + – 6MHz 20pF 20pF 1 F XTAL1 XTAL2 RESET EA SS INT T0 T1 P10 P17 P20 P27 DB0 DB7 PORT 1 PORT 2 BUS PORT VCC VDD VSS 5V GND ALE PSEN PROG WR RD 8048 NC NC NC NC = NO CONNECT Figure 11. AD654 VFC as an ADC FREQUENCY DOUBLING Since the AD654’s output is a square-wave rather than a pulse train, information about the input signal is carried on both halves of the output waveform. The circuit in Figure 12 converts the output into a pulse train, effectively doubling the output frequency, while preserving the better low frequency linearity of the AD654. This circuit also accommodates an input voltage that is greater than the AD654 supply voltage. Resistors R1–R3 are used to scale the 0 V to +10 V input voltage down to 0 V to +1 V as seen at Pin 4 of the AD654. Recall that VIN must be less than VSUPPLY –4 V, or in this case less than 1 V. The timing resistor and capacitor are selected such that this 0 V to +1 V signal seen at Pin 4 results in a 0 kHz to 200 kHz output frequency. The use of R4, C1 and the XOR gate doubles this 200 kHz output frequency to 400 kHz. The AD654 output transistor is basically used as a switch, switching capacitor C1 between a charging mode and a discharging mode of operation. The voltages seen at the input of the 74LS86 are shown in the waveform dia- gram. Due to the difference in the charge and discharge time constants, the output pulse widths of the 74LS86 are not equal. The output pulse is wider when the capacitor is charging due to its longer rise time than fall time. The pulses should therefore be counted on their rising, rather than falling, edges. AD654 RT 1k CT 500pF RPU 2.87k R3 1k R2 2k R1 8.06k C1 1000pF R4 1k 5V A B C 74LS86 VIN (0V TO 10V) V/F OUTPUT FS = 400MHz OFF ON V 0 V 0 5 0 TRANSISTOR A B C WAVEFORM DIAGRAM OSC/ DRIVER Figure 12. Frequency Doubler C |
Similar Part No. - AD654JNZ |
|
Similar Description - AD654JNZ |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List All Rights Reserved©Alldatasheet.com |
Russian : Alldatasheetru.com | Korean : Alldatasheet.co.kr | Spanish : Alldatasheet.es | French : Alldatasheet.fr | Italian : Alldatasheetit.com Portuguese : Alldatasheetpt.com | Polish : Alldatasheet.pl | Vietnamese : Alldatasheet.vn Indian : Alldatasheet.in | Mexican : Alldatasheet.com.mx | British : Alldatasheet.co.uk | New Zealand : Alldatasheet.co.nz |
Family Site : ic2ic.com |
icmetro.com |