BD7902CFS

Optical disc ICs

16/17

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Application example

1

14

15

16

17

18

19

20

21

22

23

24

25

26

27

2

3

10

9

12

13

11

6

4

5

7

8

54

41

40

39

38

37

36

35

34

33

32

31

30

29

28

53

52

45

46

43

42

44

49

51

50

48

47

PRE

LOGIC

FF

FF

FF

LIMIT

Current

LIMIT

HALL

BIAS

FG

REVERSE

DETECT

Current

COMP

OSC

Polarity

COMP

PWM

OUT

LIMIT

OSC

PRE

LOGIC

STBY/

BRAKE

CONTROL

LEVEL

SHIFT

LEVEL

SHIFT

LEVEL

SHIFT

TSD

3-phase

MATRIX

−

−

47k

47k

94k

47k

15k

15k

47k

47k

−

−

94k

94k

47k

47k

FG

FG

LOADING

IN

VC

FOCUS

IN

TRACKING

IN

LOADING

TRACKING

=5V

=12V

AVM

=5V

Fig.3

µ-COM

µ-COM

SPINDLE

IN

5V

SPVM

=12V

SPRNF

SPINDLE

SLED

IN1

SLED

IN2

SLVM

=12V

M

FOCUS

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Operation notes

(1) Wiring for SPRNF and SLRNF

Considering the wiring resistance, connect each detecting resistor as close as possible to the current detection

terminals for the spindle drive SPRNF (pin 20) and the sled motor drive SLRNF 1 and 2 (pin 31 and 32) of the IC.

(2) Current detection reference voltage

The detection of current in the spindle and sled involves the detection of voltage between the detection resistances,

applied to SLVDD (pin 30) by the sled.

corresponding power supply voltages to prevent voltage differences.