Moteur de recherche de fiches techniques de composants électroniques |
|
AD5429YRU-REEL Fiches technique(PDF) 15 Page - Analog Devices |
|
AD5429YRU-REEL Fiches technique(HTML) 15 Page - Analog Devices |
15 / 32 page AD5429/AD5439/AD5449 Rev. C | Page 15 of 32 THEORY OF OPERATION DIGITAL-TO-ANALOG CONVERTER The AD5429/AD5439/AD5449 are 8-, 10-, and 12-bit, dual- channel, current output DACs consisting of a standard inverting R-2R ladder configuration. Figure 37 shows a simplified diagram for a single channel of the AD5449. The feedback resistor, RFBA, has a value of R. The value of R is typically 10 kΩ (with a minimum of 8 kΩ and a maximum of 12 kΩ). If IOUT1A and IOUT2A are kept at the same potential, a constant current flows into each ladder leg, regardless of digital input code. Therefore, the input resistance presented at VREFA is always constant. 2R S1 2R S2 2R S3 2R S12 2R DAC DATA LATCHES AND DRIVERS R RFBA IOUT1A IOUT2A VREFA RR R Figure 37. Simplified Ladder Access is provided to the VREFx, RFBx, IOUT1x, and IOUT2x termi- nals of the DACs, making the devices extremely versatile and allowing them to be configured in several operating modes, such as unipolar mode, bipolar output mode, or single-supply mode. CIRCUIT OPERATION Unipolar Mode Using a single op amp, these devices can easily be configured to provide 2-quadrant multiplying operation or a unipolar output voltage swing, as shown in Figure 38. When an output amplifier is connected in unipolar mode, the output voltage is given by n REF OUT D V V 2 / × − = where: D is the fractional representation of the digital word loaded to the DAC. D = 0 to 255 (AD5429) = 0 to 1023 (AD5439) = 0 to 4095 (AD5449) n is the number of bits. With a fixed 10 V reference, the circuit shown in Figure 38 gives a unipolar 0 V to −10 V output voltage swing. When VIN is an ac signal, the circuit performs 2-quadrant multiplication. Table 5 shows the relationship between digital code and the expected output voltage for unipolar operation using the 8-bit AD5429 DAC. Table 5. Unipolar Code Table Digital Input Analog Output (V) 1111 1111 −VREF (255/256) 1000 0000 −VREF (128/256) = −VREF/2 0000 0001 −VREF (1/256) 0000 0000 −VREF (0/256) = 0 AD5429/ AD5439/ AD5449 NOTES 1. R1 AND R2 USED ONLY IF GAIN ADJUSTMENT IS REQUIRED. 2. C1 PHASE COMPENSATION (1pF TO 2pF) MAY BE REQUIRED 3. DAC B OMITTED FOR CLARITY. IOUT1A IOUT2A VREFx VDD C1 A1 VOUT = 0V TO –VREF AGND R2 VDD VREF SDIN GND SCLK SYNC RFBA R1 IF A1 IS A HIGH SPEED AMPLIFIER. MICROCONTROLLER Figure 38. Unipolar Operation |
Numéro de pièce similaire - AD5429YRU-REEL |
|
Description similaire - AD5429YRU-REEL |
|
|
Lien URL |
Politique de confidentialité |
ALLDATASHEET.FR |
ALLDATASHEET vous a-t-il été utile ? [ DONATE ] |
À propos de Alldatasheet | Publicité | Contactez-nous | Politique de confidentialité | Echange de liens | Fabricants 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 |