FAN8042 데이터 시트보기 (PDF) - Fairchild Semiconductor

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FAN8042

5-CH Motor Driver

Fairchild Semiconductor 

4. Tsd Monitor Function

• PIN23 is TSD monitor pin which detects the state of the TSD block and generates the TSD-monitor signal.

• In normal state Q5 is turned on, so Q6 is turned off. on the otherhand, When the TSD block is is activated then Q5 is turned

off, so the voltage of pin23 is low.

• Truth table is as follows

pin23

FAN8042

High

Tsd Off

Low

Tsd On

5. Focus, Tracking Actuator, Spindle, Sled Motor Drive Part

OPin+ 1 4 9 12

OPin- 2 5 10 13

3 8 11 14

Vref 44

R1

+

Vin

−

R1

Vp

R2

PVCC1(PVCC2)

Dp

60k

+

−

62k

Qp

R1

Vp

R2

−

+

R2

R2

+

−

R2

DOP 28 32 34 36

M

DON 27 29 33 35

• The voltage, Vref is the reference voltage given by the external bias voltage of the pin 44.

• The input signal (Vin) through pins 1,4,9, 12 is amplified one time and then fed to the output stage.

(assume that input opamp was used as a buffer)

• The total closed loop voltage gain is as follows

Vin = Vref + ∆V

DOP= Vp + 4∆V

DON= Vp–4∆V

Vout = DOP – DON= 8∆V

Gain = 20log V---∆--o--V-u----t = 20log 8= 18dB

• If you want to change the total closed loop voltage gain, you must use the input opamp as an amplifier

• The output stage is the balanced transformerless (BTL) driver.

• The bias voltage Vp is expressed as ;

Vp

=

(PVCC1

–

VDp

–

VcesatQp)

×

---------6---2----k---------

60k + 62k

+

VcesatQp

= P-----V----C-----C-----1-----–----V----D-----p-----+-----V----c----e---s----a---t--Q-----p-- + VcesatQp

1.97

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