Electronic Components Datasheet Search |
|
ADS5121 Datasheet(PDF) 12 Page - Texas Instruments |
|
ADS5121 Datasheet(HTML) 12 Page - Texas Instruments |
12 / 17 page ADS5121 12 SBAS281 www.ti.com The differential input configuration may provide a noticeable advantage of achieving good SFDR performance over a wide range of input frequencies. In this mode, both inputs (AIN+ and AIN–) of the ADS5121 see matched impedances. Figure 1 shows the schematic for the suggested transformer- coupled interface circuit. The component values of the R-C low-pass may be optimized depending on the desired roll-off frequency. Single-Ended, AC-Coupled Driver The circuit of Figure 2 shows an example for driving the inputs of the ADS5121 in a single-ended configuration. The signal is AC-coupled between the driver amplifier and the converter input (AIN+). This allows for setting the required common-mode voltages for the ADC and op amp separately. The single-supply op amp is biased at mid-supply by two resistors connected at its noninverting input. Connecting each input to the CML pin provides the required common- mode voltage for the inputs of the ADS5121. Here, two resistors of equal value ensure that the inputs see closely matched source impedances. If the op amp features a disable function, it could be easily tied together with the power-down pin of the ADS5121 channel (STBY). In the circuit example depicted in Figure 2, the OPA355’s EN pin is directly connected to the STBY pin to allow for a power-down mode of the entire circuit. Other suitable op amps for single- supply driver applications include the OPA634, OPA635, or OPA690, for example. DC-Coupled Interface with Differential Amplifier Differential input/output amplifiers can simplify the driver circuit for applications requiring input DC-coupling. Flexible in their configurations, such amplifiers can be used for single- ended to differential conversion, allow for signal amplifica- tion, and also for filtering prior to the ADC. See Figure 3 for one possible circuit implementation using the THS4130 am- plifier. Here, the amplifier operates with a gain of +1. The common- mode voltage available at the CML pin can be conveniently connected to the amplifier’s VOCM pin to set the required input bias for the ADS5121. FIGURE 1. Converting a Single-Ended Input Signal into a Differential Signal Using an RF-Transformer. FIGURE 2. Single-Ended, AC-Coupled Driver Configuration for a Single Supply. R IN R IN C IN 0.1 µF R T 0.1 µF 1:n R S OPA690 R 1 R 2 V IN ADS5121 AIN+ AIN– CML –5V +5V OPA355 V IN R F 604 Ω R G 604 Ω 1.82k Ω 1.82k Ω ADS5121 R S 24 Ω EN 33pF 0.1 µF 0.1 µF R 1 AIN+ STBY CML AIN– 0.1 µF 0.1 µF R 2 +3V/+5V |
Similar Part No. - ADS5121 |
|
Similar Description - ADS5121 |
|
|
Link URL |
Privacy Policy |
ALLDATASHEET.COM |
Does ALLDATASHEET help your business so far? [ DONATE ] |
About Alldatasheet | Advertisement | Datasheet Upload | Contact us | Privacy Policy | Link Exchange | Manufacturer List 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 |