TDA5341 Datasheet, PDF (13/28 Pages) NXP Semiconductors – Brushless DC motor and VCM drive circuit with speed control

Philips Semiconductors
Brushless DC motor and VCM drive circuit
with speed control
Product specification
TDA5341
The power for retraction is received from the rectification
of the EMF of the spindle before it is spun down.
After retraction, a brake procedure is automatically settled.
The time needed for retraction, prior to braking, can be
precisely adjusted with the external RC device connected
to pin BRAKEDELAY. The discharge of the capacitance
across the resistance from V_DD − 0.7 V down to 1 V will
provide the desired time constant.
Actuator section
The actuator driver has a control input voltage that is
proportional to the actuator current which is capable of a
closed-loop band-pass frequency higher than 10 kHz.
An operational amplifier input allows passive external
components for compensation and gain setting.
The compensation amplifier is able to be pulled out of a
saturation state within 5 µs and its output swing is
V_DD − 1.5 V.
An actuator current-sense amplifier is provided for use by
the disc drive controller. The gain from current-sense
resistor to sense the amplifier output is typically 10 (±3%)
and the output voltage swing is ±1.25 V. An input common
mode range insures operation through all normal coil
voltage excursions. Maximum recovery time from
saturation is 20 µs (typ.).
TRANSFER FUNCTION
handbook, full pagewidth
input
RIN1
RIN2
VCMIN2
GAINSEL
Rf
VCMIN1
Vref
SENSEOUT
CL1
actuator
CL2
Rs
FB2 FB1 VCM− VCM+ SENSEIN− SENSEIN+
PREAMP
TDA5341
OUTPUT
GAIN 11
SENSE
AMP
MGE825
Fig.6 VCM section application diagram.
T
=
–11
×
R_f
×
Z_L
×


-R----_I--_N----_×------₍---R----_f---_×-----R-----_s---₊-----R-----_f---_×----Z1----_V----_C---_M------₊----1----1---0-----_×-----R----_s----_×-----Z----_L---₎-


With GAINSEL = HIGH; R_IN = R_IN1
With GAINSEL = LOW; R_IN = ^R-R----I-_I-^NN---₁₁----₊^×-----RR-----^II-_NN---₂-²-
1997 Jul 10
13