BD7905BFS Datasheet, PDF (15/18 Pages) Rohm – 6CH Power Driver for CD-ROM, DVD-ROM

Optical disc ICs
BD7905BFS
6. Muting functions
a) VC-drop muting
When the voltage at VC terminal (pin 27) drops to a value lower than 0.7V (Typ.), the outputs of all the channels are
turned off. Set the VC terminal voltage to larger than 1.0V.
b) VCC-drop muting
When the voltages at DVCC terminal (pin 54) and VCC terminal (pin 51) drop to lower than 3.8V (Typ.), the outputs of
all the channels are turned off.
7. Thermal-shutdown
A thermal-shutdown circuit (over-temperature protection circuit) is built in to prevent the IC from thermal breakdown.
Use the IC under the thermal loss allowed to the package. In case the IC is left running over the allowable loss, the
junction temperature rises, and the thermal-shutdown circuit works at the junction temperature of 175°C (Typ.) (the
outputs of all the channels are turned off). When the junction temperature drops to 150°C (Typ.), the IC start operating
again.
!Application example
DVCC=5V
TRACKING
FOCUS IN
IN
LOADING
M
VCC=12V
TRACKING
FOCUS
AVM=5V
SLVM=12V
SLED SLED
IN2 IN1
54 53 52 51 50 49 48 47 46 45 44 43 42 41 40 39 38 37 36 35 34 33 32 31 30 29 28
47k
LEVEL
SHIFT
LEVEL
SHIFT
LEVEL
SHIFT
47k _−
+
117.5k
117.5k
47k −
+
TSD
OSC
PRE
LOGIC
FF
PRE
LOGIC
FF
−
67k
47k
−
67k
LIMIT
LIMIT
FG
REVERSE
DETECT
HALL
BIAS
OSC
Polarity
COMP
Current
LIMIT
PRE LOGIC
75k
FG
112.5k
STBY/
BRAKE
CONTROL
188k
47k
1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27
SPINDLE
SPRNF
FG
µ-COM
µ-COM
SPINDLE
IN
5V
VC
LOADING
IN
SPVM=12V
Fig.3
15/17