Os motores de busca de Datasheet de Componentes eletrônicos |
|
AD570JD Folha de dados(PDF) 5 Page - Analog Devices |
|
AD570JD Folha de dados(HTML) 5 Page - Analog Devices |
5 / 8 page AD570 REV. A –5– ZERO OFFSET The apparent zero point of the AD570 can be adjusted by in- serting an offset voltage between the analog common of the de- vice and the actual signal return or signal common. Figure 7 illustrates two methods of providing this offset. Figure 7a shows how the converter zero may be offset by up to ±3 bits to correct the device initial offset and/or input signal offsets. As shown, the circuit gives approximately symmetrical adjustment in unipolar mode. In bipolar mode R2 should be omitted to obtain a sym- metrical range. Figure 7a. Figure 7b. Figure 8 shows the nominal transfer curve near zero for an AD570 in unipolar mode. The code transitions are at the edges of the nominal bit weights. In some applications it will be pref- erable to offset the code transitions so that they fall between the nominal bit weights, as shown in the offset characteristics. This offset can easily be accomplished as shown in Figure 7b. At balance (after a conversion) approximately 2 mA flows into the analog common terminal. A 10 Ω resistor in series with this terminal will result in approximately the desired 1/2 bit offset of the transfer characteristics. The nominal 2 mA analog common current is not closely controlled in manufacture. If high accuracy is required, a 20 Ω potentiometer (connected as a rheostat) can be used as R1. Additional negative offset range may be obtained by using larger values of R1. Of course, if the zero transition point is changed, the full-scale transition point will also move. Thus, if an offset of 1/2 LSB is introduced, full-scale trimming as described on previous page should be done with an analog input of 9.941 volts. Figure 8. AD570 Transfer Curve—Unipolar Operation (Approximate Bit Weights Shown for Illustration, Nominal Bit Weights 36.1 mV) NOTE: During a conversion transient currents from the analog common terminal will disturb the offset voltage. Capacitive de- coupling should not be used around the offset network. These transients will settle as appropriate during a conversion. Capaci- tive decoupling will “pump up” and fail to settle resulting in conversion errors. Power supply decoupling which returns to analog signal common should go to the signal input side of the resistive offset network. CONTROL AND TIMING OF THE AD570 There are several important timing and control features on the AD570 which must be understood precisely to allow optimal interfacing to microprocessor or other types of control systems. All of these features are shown in the timing diagram in Figure 9. The normal standby situation is shown at the left end of the drawing. The BLANK and CONVERT (B & C) line is held high, the output lines will be “open”, and the DATA READY (DR) line will be high. This mode is the lowest power state of the device (typically 150 mW). When the (B & C ) line is brought low, the conversion cycle is initiated; but the DR and data lines do not change state. When the conversion cycle is complete (typically 25 µs), the DR line goes low, and within 500 ns, the data lines become active with the new data. About 1.5 µs after the B & C line is again brought high, the DR line will go high and the data lines will go open. When the B & C line is again brought low, a new conversion will begin. The minimum pulse width for the B & C line to blank previous data and start a new conversion is 2 µs. If the B & C line is brought high during a conversion, the conversion will stop, and |
Nº de peça semelhante - AD570JD |
|
Descrição semelhante - AD570JD |
|
|
Ligação URL |
Privacy Policy |
ALLDATASHEETPT.COM |
ALLDATASHEET é útil para você? [ DONATE ] |
Sobre Alldatasheet | Publicidade | Contato conosco | Privacy Policy | roca de Link | Lista de Fabricantes 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 |