ADS7890

SLAS409 − DECEMBER 2003

www.ti.com

10

D12

D13

td8

23

9

10

16

SCLK

CS

BUSY

SDO

Figure 6. Frame Abort During Sample

The falling edge of CS during a conversion (from BUSY high until the end of t(conv) as shown in Figure 7) aborts

the ongoing conversion. This starts the next frame. The device outputs 3F80 (hex) on SDO during the first frame

after the conversion abort.

MSB

Busy Fall Without

Conversion Abort

2

3

15

16

1

2

3

4

5

tw2

td4

t(CONV)

3F80 (hex)

SCLK

CS

BUSY

SDO

Figure 7. Frame Abort During Conversion

FRAME ABORT IN DSP INTERFACE MODE

The rising edge of FS (see Figure 8) or the rising edge of CS (see Figure 9) after the falling edge of FS and

before the 9th rising edge of SCLK aborts the frame. SDO goes to three-state with CS high and a new frame

is started with the rising edge of FS (see Figure 8 and Figure 9). Previous conversion results are available on

SDO during the new frame.

MSB− D13

D12

D6

MSB−D13

LSB−D0

2

3

8

9

2

3

15

16

Data From Last Conversion

SCLK

FS

BUSY

CS

SDO

(Held Low)

Figure 8. Frame Abort Using FS Before Sample Start