AN3302

Test results

Doc ID 18163 Rev 1

7/13

3.1

S-wire protocol

The device implements an S-wire bus communication that uses one control signal coming

from the microprocessor to program the STODD01 output voltage (see Figure 10).

S-wire protocol allows to change the feedback voltage of the step-up section from 0.8 to

1.25 V, with steps of 15 mV. This feature allows complete and easy control of the laser diode

power during read and write operation.

If this function isn't used, the TX pin must be connected to GND.

The TX pin must be set to '1' after programming. If TX is programmed with 0 S-wire pulses,

Figure 10.

Wire connection

AM07858v1

Reset

TX

EN

GND

EN

TX

Reset

STODD01

GND

GND

µP

GND

AM07858v1

Reset

TX

EN

GND

EN

TX

Reset

STODD01

GND

GND

µP

GND

Table 2.

Feedback one voltage level

S-wire pulses

S-wire pulses

S-wire pulses

0 (Default Value)

0.800

11

0.965

22

1.130

1

0.815

12

0.980

23

1.145

2

0.830

13

0.995

24

1.160

3

0.845

14

1.010

25

1.175

4

0.860

15

1.025

26

1.190

5

0.875

16

1.040

27

1.205

6

0.890

17

1.055

28

1.220

7

0.905

18

1.070

29

1.235

8

0.920

19

1.085

30

1.250

9

0.935

20

1.100

10

0.950

21

1.115