ADS7891IPFBT datasheet(10/31 Pages) TI1

10 / 31 page

ADS7891

SLAS410 − DECEMBER 2003

www.ti.com

D13−6 & D5−0

D5−0

Conversion No N

Data For Conv. N

Data For Conv. N−1

CONVST

BUSY

D13−D0

td1 + t(acq)

BYTE

td10

td7

td8

td2

Figure 6. Read Control Via CS and RD Tied to BDGND

DEVICE OPERATION AND DATA READ IN BACK-TO-BACK CONVERSION

The following two figures illustrate device operation in back-to-back conversion mode. It is possible to operate

the device at any throughput in this mode, but this is the only mode in which the device can be operated at

throughputs exceeding 2.8 MSPS.

A conversion starts on the CONVST falling edge. The BUSY output goes high after a delay (td2). Note that care

must be taken not to abort the conversion (see Figure 4) apart from timing restrictions shown in Figure 7 and

Figure 8. The conversion ends within the conversion time, t(conv), after the CONVST falling edge. The new

acquisition can be immediately started without waiting for the BUSY signal to go low. This can be ensured with

a CONVST high pulse width that is more than or equal to (t0 – t(conv) + 10 nsec) which is tw4 for a 3-MHz operation.

Sample N

Conversion N

Data For Conversion N−1

(Data read Without Latency)

CONVST

BUSY

D13−D0

t(conv) + td11

tw4

tw5

t(acq)

td12

t0 = 333 ns for 3 MSPS Operation

Figure 7. Back-To-Back Operation With CS and RD Low

ADS7891IPFBT Datasheet(PDF) 10 Page - Texas Instruments