selected, SSTRB does not go into a high-impedance

state when

CS goes high.

Figure 10 shows the SSTRB timing in internal clock

mode. In this mode, data can be shifted in and out of

the MAX1245 at clock rates exceeding 1.5MHz, provid-

above 2.0µs.

Data Framing

The falling edge of

CS does not start a conversion on

the MAX1245. The first logic high clocked into DIN is

interpreted as a start bit and defines the first bit of the

control byte. A conversion starts on the falling edge of

SCLK, after the eighth bit of the control byte (the PD0

bit) is clocked into DIN. The start bit is defined as:

The first high bit clocked into DIN with

CS low any

OR

The first high bit clocked into DIN after bit 5 of a con-

version in progress is clocked onto the DOUT pin.

If CS is toggled before the current conversion is com-

plete, then the next high bit clocked into DIN is recog-

nized as a start bit; the current conversion is terminated,

and a new one is started.

+2.375V, Low-Power, 8-Channel,

Serial 12-Bit ADC

______________________________________________________________________________________

13

SSTRB

CS

SCLK

DIN

DOUT

14

8

12

18

20

24

START

SEL2 SEL1 SEL0

UNI/

BIP

SGL/

DIF

PD1 PD0

B11

MSB B10

B9

B2

B1

B0

LSB

FILLED WITH

ZEROS

IDLE

CONVERSION

7.5µs MAX

(SHDN = FLOAT)

2

3

5

6

7

9

10

11

19

21

22

23

ACQUISITION

(SCLK = 1.5MHz)

IDLE

A/D STATE

2.0µs

PD0 CLOCK IN

SSTRB

• • •

SCLK

• • •

DOUT

• • •

NOTE: FOR BEST NOISE PERFORMANCE, KEEP SCLK LOW DURING CONVERSION.

CS

• • •

Figure 9. Internal Clock Mode Timing

Figure 10. Internal Clock Mode SSTRB Detailed Timing