Motor de Búsqueda de Datasheet de Componentes Electrónicos |
|
AD7538SQ Datasheet(PDF) 5 Page - Analog Devices |
|
AD7538SQ Datasheet(HTML) 5 Page - Analog Devices |
5 / 8 page AD7538 REV. A –5– EQUIVALENT CIRCUIT ANALYSIS Figure 3 shows an equivalent circuit for the analog section of the AD7538 D/A converter. The current source ILEAKAGE is composed of surface and junction leakages. The resistor RO denotes the equivalent output resistance of the DAC which varies with input code. COUT is the capacitance due to the cur- rent steering switches and varies from about 90 pF to 180 pF (typical values) depending upon the digital input. g(VREF, N) is the Thevenin equivalent voltage generator due to the reference input voltage, VREF, and the transfer function of the DAC ladder, N. Figure 3. AD7538 Equivalent Analog Output Circuit DIGITAL SECTION The digital inputs are designed to be both TTL and 5 V CMOS compatible. All logic inputs are static protected MOS gates with typical input currents of less than 1 nA. To minimize power supply currents, it is recommended that the digital input volt- ages be driven as close as possible to 0 V and 5 V logic levels. UNIPOLAR BINARY OPERATION (2-QUADRANT MULTIPLICATION) Figure 4 shows the circuit diagram for unipolar binary opera- tion. With an ac input, the circuit performs 2 quadrant multipli- cation. The code table for Figure 4 is given in Table I. Capacitor C1 provides phase compensation and helps prevent overshoot and ringing when high-speed op amps are used. The R-2R ladder current is 1/8 of the total reference input cur- rent. 7/8 I flows in the parallel ladder structure. Switches A-G steer equally weighted currents between IOUT and AGND. Since the input resistance at VREF is constant, it may be driven by a voltage source or a current source of positive or negative polarity. CIRCUIT INFORMATION Figure 2. Simplified Circuit Diagram for the AD7538 D/A Section Figure 4. Unipolar Binary Operation Table I. Unipolar Binary Code Table for AD7538 Binary Number In DAC Register Analog Output, VOUT MSB LSB 11 1111 1111 1111 –VIN 16383 16384 10 0000 0000 0000 –VIN 8192 16384 = –1/ 2V IN 00 0000 0000 0001 –VIN 1 16384 00 0000 0000 0000 0 V D/A SECTION Figure 2 shows a simplified circuit diagram for the AD7538 D/A section. The three MSBs of the 14-bit Data Word are de- coded to drive the seven switches A-G. The 11 LSBs of the Data Word consist of an R-2R ladder operated in a current steering configuration. |
Número de pieza similar - AD7538SQ |
|
Descripción similar - AD7538SQ |
|
|
Enlace URL |
Política de Privacidad |
ALLDATASHEET.ES |
¿ALLDATASHEET es útil para Ud.? [ DONATE ] |
Todo acerca de Alldatasheet | Publicidad | Contáctenos | Política de Privacidad | Intercambio de Enlaces | 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 |