Moteur de recherche de fiches techniques de composants électroniques |
|
AD694BRZ Fiches technique(PDF) 4 Page - Analog Devices |
|
AD694BRZ Fiches technique(HTML) 4 Page - Analog Devices |
4 / 16 page AD694 –4– REV. B Typical Minimum Supply Voltage vs. Temperature for 2 V and 10 V Full Scale Maximum RL vs. Supply Voltage Voltage Reference Power Supply Rejection IOUT: Voltage Compliance vs. Temperature FUNCTIONAL DESCRIPTION The operation of the AD694 can best be understood by dividing the circuit into three functional parts (see Figure 1). First, a single supply input amplifier buffers the high level, single-ended input signal. The buffer amplifier drives the second section, a voltage to current (V/I) converter, that makes a 0 to 16 mA sig- nal dependent current. Figure 1. Functional Block Diagram The third section, a voltage reference and offset generator, is re- sponsible for providing the 4 mA offset current signal. BUFFER AMPLIFIER The buffer amplifier is a single supply amplifier that may be used as a unity gain buffer, an output amplifier for a current output DAC, or as a gain block to amplify low level signals. The amplifier’s PNP input stage has a common-mode range that ex- tends from a few hundred mV below ground to within 2.5 V of VS. The Class A output of the amplifier appears at Pin 1 (FB). The output range extends from about 1 mV above common to within 2.5 V of VS when the amplifier is operated as a follower. The amplifier can source a maximum load of 5 k Ω, but can sink only as much as its internal 10 k Ω pulldown resistor allows. V/I CONVERTER The ground referenced, input signal from the buffer amplifier is converted to a 0 to 0.8 mA current by A2 and level shifted to the positive supply. A current mirror then multiplies this signal by a factor of 20 to make the signal current of 0 to 16 mA. This technique allows the output stage to drive a load to within 2 V of the positive supply (VS). Amplifier A2 forces the voltage at Pin 1 across resistors R1 and R2 by driving the Darlington tran- sistor, Q2. The high gain Darlington transmits the resistor cur- rent to its collector and to R3 (900 Ω). A3 forces the level shifted signal across the 45 Ω resistor to get a current gain of 20. The transfer function of the V/I stage is therefore: IV R1 R2 OUT PIN1 =× + () 20 / resulting in a 0-16 mA output swing for a 0–10 V input. Tying Pin 4 (2 V FS) to ground shorts out R2 and results in a 2 V full-scale input for a 16 mA output span. The output stage of the V/I converter is of a unique design that allows the IOUT pin to drive a load below the common (sub- strate) potential of the device. The output transistor can always drive a load to a point 36 V below the positive supply (VS). An |
Numéro de pièce similaire - AD694BRZ |
|
Description similaire - AD694BRZ |
|
|
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 |