THS12082

12-BIT, 8 MSPS, SIMULTANEOUS SAMPLING ANALOG-TO-DIGITAL CONVERTERS

SLAS271 – MAY 2000

13

POST OFFICE BOX 655303

FIFO description

In order to facilitate an efficient connection to today’s processors, the THS12082 is supplied with a FIFO. This

integrated FIFO enables a problem-free processing of data. The FIFO is provided as a flexible circular buffer.

The circular buffer integrated in the THS12082 can store up to 16 conversion values. Therefore, the number

of interrupts to be served by a processor can be reduced significantly.

8

9

10

11

12

13

14

15

16

1

2

3

4

5

6

7

Read Pointer

Trigger Pointer

Write Pointer

Data in FIFO

Free

Figure 4. Circular Buffer

The converted data of the THS12082 is automatically written into the FIFO. To control the writing and reading

process, a write pointer, a read pointer, and a trigger pointer are used. The read pointer always shows the

location which will be read next. The write pointer indicates the location which contains the last written sample.

With a selection of multiple analog input channels, the converted values are written in a predefined sequence

to the circular buffer (Autoscan Mode). In this way, the channel information for the reading processor is

continually maintained.

The FIFO can be programmed through the control register of the ADC. The user has the ability to select a

specific trigger level from Table 13 in order to choose the configuration which best fits the application. The FIFO

provides the signal DATA_AV, which signals the processor to read the amount of data equal to the trigger level

selected in Table 13. The signal DATA_AV becomes active when the trigger condition is satisfied. The trigger

condition is satisfied when as many values as selected for the trigger level where written into the FIFO.

The signal DATA_AV could be connected to an interrupt input of a processor. In every interrupt service routine

call, the processor must read the amount of data equal to the trigger level from the ADC. The first data represents

the first channel according to the autoscan mode, which is shown in Table 10. The channel information is

therefore always maintained.