KA3030 查看數據表（PDF） - Fairchild Semiconductor
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KA3030 Datasheet PDF : 17 Pages
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KA3030D
4. FOCUS, TRACKING, SPINDLE, SLED DRIVE CIRCUITS
M
V1’
V2’
−+
V1
Rref
IC
GV2
VREF
+−
V2
−
+
LEVEL SHIFTER
GV1
+−
VREF
(pin 23)
VIN
GV = 20log (VO/VIN) = GV1 + GV2 = 3.5dB + 6dB = 9.5dB
Vref is fixed to 2.5V as the external bias voltage and the input signal through the VIN is amplified to about 9.5dB through two
state AMP.
In the level shift circuitry, the input signal is transformed into the current so that the voltage V1 and V2 are shifted to V1’ and
V2’ respectively.
V1’ = V1 + (IC × VREF) = V1 + ∆V
V2’ = V2 − (IC × VREF) = V2 − ∆V
Because V1 and V2 voltages, in their initial state, are equal, the voltage, VM, on the sides of the motor is following VM = V1’
− V2’ = ∆V − (−)∆V = 2∆V
Rotation occurs due to 2∆V voltage difference at both sides of the motor.
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