863
Motor driver ICs
3-phase motor driver for
CD-ROMs
BA6849FP / BA6849FP-Y / BA6849FM /
BA6849FS
The BA6849 series are ICs developed for CD-ROM spindle motor drives. These ICs possess a short brake and reverse-
rotation brake for two types of brake functions, and also contain FG output and rotation direction detection (FR) circuits,
making them high-functionality and high-performance ICs.
Applications
CD-ROM, CD-R, CD-RW, DVD-ROM, and DVD-RAM
Features
1) Three-phase, full-wave, pseudo-linear drive system.
2) Built-in power save and thermal shutdown functions.
3) Built-in current limiter and Hall bias circuits.
4) Built-in FG output.
5) Built-in rotation direction detector.
6) Built-in reverse rotation prevention circuit.
7) Built-in short brake pin.
Absolute maximum ratings (Ta = 25C)
864
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
Recommended operating conditions (Ta = 25C)
Block diagram
865
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
Pin descriptions
BA6849FP/BA6849FM BA6849FP-Y
866
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
MA6849FS
867
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
Input / output circuits
(1) Power save
(3) Torque output (A1, A2, and A3)
(4) Hall input (H1, H1–, H2, H2–, H3, H3–)
(2) Torque command input
868
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
(5) Hall bias
(6) FG output
(7) FR Output
(8) Short brake
Note: Resistance values are typical values.
869
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
Electrical characteristics (unless otherwise noted, Ta = 25C, VCC = 5V, VM1 = 12V, VM2 = 12V)
870
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
Circuit operation
(1) Hall input to coil output
The phase relationship between the Hall input signals and the output current and voltage is shown in Fig.9. The motor
position data input via the Hall pins is amplified by the Hall amplifier, and formed into waveforms by the matrix
block.These signals are input to the output driver that supplies the drive current to the motor coils.
871
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
(2) Torque command
The RNF pin voltage with respect to the torque command
(EC) is as follows:
The I / O gain (GEC) from the EC pin to the RNF pin (output
current) is determined by the RNF detector resistor.
GEC = 0.255 / RNF [A / V]
The torque limit current ITL is given by:
ITL = 0.35 / RNF [A]
(3) Reverse rotation detection function
The reverse detection circuit construction is shown in
Fig.11.
(1) Forward (EC < ECR)
The phase relationship between the Hall input signals
H2 and H3 becomes as shown in Fig.9, and the re-
verse rotation detection circuit does not operate.
(2) Reverse (EC > ECR)
The phase relationship between the signals H2 and
H3 is opposite that for forward operation, and the re-
verse rotation detection circuit operates. The output
goes OFF, and becomes open circuit.
872
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
(4) Short brake
When 3.5V or more is applied to the short brake pin, the
upper-side output transistors of all go off, and the lower-
side output transistors go on. Short braking operates re-
gardless of the torque command signal.
(5) Other circuits
When 3.5V or more is applied to the power save pin, all
circuits are on. When 1.5V or less is applied, the IC en-
ters power save mode. Also, the Hall bias pins turn on
and off with the power save pin.
Application example
873
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
Operation notes
(1) Power save
The power save input is an I / O circuit like the own
shown in Fig.1.
The thermal derating characteristics of the power save
pin is –8mV / C, and the resistance will fluctuate be-
tween ±30% so be careful of the input voltage range.
(2) Hall input
The input circuit shown in Fig.4 is used for the Hall inputs.
The Hall elements can be connected either in series or
in parallel.
(3) Thermal shutdown (TSD)
When the junction temperature reaches 175C, the A1,
A2, and A3 coil outputs go open circuit. The thermal shut-
down has approximately 15C of hysteresis.
Electrical characteristics curves
874
Motor driver ICs BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
External dimensions (Units: mm)
Appendix
Appendix1-Rev1.0
The products listed in this document are designed to be used with ordinary electronic equipment or devices
(such as audio visual equipment, office-automation equipment, communications devices, electrical
appliances and electronic toys).
Should you intend to use these products with equipment or devices which require an extremely high level of
reliability and the malfunction of with would directly endanger human life (such as medical instruments,
transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other
safety devices), please be sure to consult with our sales representative in advance.
Notes
No technical content pages of this document may be reproduced in any form or transmitted by any
means without prior permission of ROHM CO.,LTD.
The contents described herein are subject to change without notice. The specifications for the
product described in this document are for reference only. Upon actual use, therefore, please request
that specifications to be separately delivered.
Application circuit diagrams and circuit constants contained herein are shown as examples of standard
use and operation. Please pay careful attention to the peripheral conditions when designing circuits
and deciding upon circuit constants in the set.
Any data, including, but not limited to application circuit diagrams information, described herein
are intended only as illustrations of such devices and not as the specifications for such devices. ROHM
CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any
third party's intellectual property rights or other proprietary rights, and further, assumes no liability of
whatsoever nature in the event of any such infringement, or arising from or connected with or related
to the use of such devices.
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exploit any intellectual property rights or other proprietary rights owned or controlled by
ROHM CO., LTD. is granted to any such buyer.
Products listed in this document use silicon as a basic material.
Products listed in this document are no antiradiation design.
About Export Control Order in Japan
Products described herein are the objects of controlled goods in Annex 1 (Item 16) of Export Trade Control
Order in Japan.
In case of export from Japan, please confirm if it applies to "objective" criteria or an "informed" (by MITI clause)
on the basis of "catch all controls for Non-Proliferation of Weapons of Mass Destruction.
