TLV571

2.7 V TO 5.5 V, 1-CHANNEL, 8-BIT,

PARALLEL ANALOG-TO-DIGITAL CONVERTER

SLAS239A – SEPTEMBER 1999 – REVISED FEBRUARY 2000

7

POST OFFICE BOX 655303

start of conversion mechanism

There are two ways to convert data: hardware and software. In the hardware conversion mode the ADC begins

sampling at the falling edge of CSTART and begins conversion at the rising edge of CSTART. Software start

mode ADC samples for 6 clocks, then conversion occurs for ten clocks. The total sampling and conversion

process lasts only 16 clocks in this case. If RD is not detected during the next clock cycle, the ADC automatically

proceeds to a power-down state. Data is valid on the rising edge of INT in both conversion modes.

hardware CSTART conversion

external clock

With CS low and WR low, data is written into the ADC. The sampling begins at the falling edge of CSTART and

conversion begins at the rising edge of CSTART. At the end of conversion, EOC goes from low to high, telling

the host that conversion is ready to be read out. The external clock is active and is used as the reference at all

times. With this mode, it is required that CSTART is not applied at the rising edge of the clock (see Figure 4).