 |
Os motores de busca de Datasheet de Componentes eletrônicos |
|
|
Os motores de busca de Datasheet de Componentes eletrônicos |
|
AD7822BR Folha de dados(PDF) 7 Page - Analog Devices |
|
||||||||||||||||||||||||||||||
AD7822BR Folha de dados(HTML) 7 Page - Analog Devices |
|
|
7 / 20 page  AD7822/AD7825/AD7829 –7– REV. B Figures 2 and 3 below show simplified schematics of the ADC. When the ADC starts a conversion, the track-and-hold goes into hold mode and holds the analog input for 120 ns. This is the acquisition phase as shown in Figure 2, when Switch 2 is in Posi- tion A. At the point when the track-and-hold returns to its track mode, this signal is sampled by the sampling capacitor as Switch 2 moves into Position B. The first flash occurs at this instant and is then followed by the second flash. Typically, the first flash is complete after 100 ns, i.e., at 220 ns, while the end of the second flash and hence the 8-bit conversion result is available at 330 ns (minimum). The maximum conversion time is 420 ns. As shown in Figure 4, the track-and-hold returns to track mode after 120 ns, and starts the next acquisition before the end of the current conversion. Figure 6 shows the ADC transfer function. TIMING AND CONTROL LOGIC R1 HOLD SAMPLING CAPACITOR A B SW2 R16 R15 R14 R13 T/H 1 VIN REFERENCE D7 D6 D5 D4 D3 D2 D1 D0 14 15 13 1 Figure 2. ADC Acquisition Phase TIMING AND CONTROL LOGIC R1 HOLD SAMPLING CAPACITOR A B SW2 R16 R15 R14 R13 T/H 1 VIN REFERENCE D7 D6 D5 D4 D3 D2 D1 D0 14 15 13 1 Figure 3. ADC Conversion Phase HOLD HOLD 120ns CONVST EOC CS RD DB0–DB7 t2 t1 t3 TRACK TRACK VALID DATA Figure 4. Track-and-Hold Timing TYPICAL CONNECTION DIAGRAM Figure 5 shows a typical connection diagram for the AD7822, AD7825, and AD7829. The AGND and DGND are connected together at the device for good noise suppression. The parallel interface is implemented using an 8-bit data bus. The end of conversion signal (EOC) idles high, the falling edge of CONVST initiates a conversion and at the end of conversion the falling edge of EOC is used to initiate an Interrupt Service Routine (ISR) on a microprocessor. (See Parallel Interface section for more details.) VREF and VMID are connected to a voltage source such as the AD780, while VDD is connected to a voltage source that can vary from 4.5 V to 5.5 V. (See Table I in Analog Input section.) When VDD is first connected, the AD7822, AD7825, and AD7829 power up in a low current mode, i.e., power-down, with the default logic level on the EOC pin on the AD7822 and AD7825 equal to a low. Ensure the CONVST line is not floating when VDD is applied, as this could put the AD7822/AD7825/ AD7829 into an unknown state. A suggestion is to tie CONVST to VDD or DGND through a pull-up or pull-down resistor. A rising edge on the CONVST pin will cause the AD7829 to fully power up while a rising edge on the PD pin will cause the AD7822 and AD7825 to fully power up. For applications where power consumption is of concern, the automatic power-down at the end of a conversion should be used to improve power performance. (See Power-Down Options section of the data sheet.) SUPPLY 4.5V TO 5.5V 10 F 0.1 F VDD VREF VMID VIN1 1.25V TO 3.75V INPUT VIN2 VIN4(8) AGND DB0–DB7 EOC RD CS CONVST A0 A1 A2 PD PARALLEL INTERFACE C/ P AD7822/ AD7825/ AD7829 DGND 2.5V AD780 Figure 5. Typical Connection Diagram |
Nº de peça semelhante - AD7822BR |
|
Descrição semelhante - AD7822BR |
|
|
|
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 |
Portuguese ▼
English
Chinese
German
Japanese
Russian
Korean
Spanish
French
Italian
Portuguese
Polish
Vietnamese
Indian
Mexican
British
New Zealand
