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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 reverserotation 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. FApplications CD-ROM, CD-R, CD-RW, DVD-ROM, and DVD-RAM FFeatures 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. FAbsolute maximum ratings (Ta = 25_C)

5) Built-in rotation direction detector. 6) Built-in reverse rotation prevention circuit. 7) Built-in short brake pin.

863

Motor driver ICs

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

FRecommended operating conditions (Ta = 25_C)

FBlock diagram

864

Motor driver ICs
FPin descriptions BA6849FP / BA6849FM

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

BA6849FP-Y

865

Motor driver ICs
MA6849FS

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

866

Motor driver ICs
FInput / output circuits (1) Power save

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

(2)

Torque command input

(3)

Torque output (A1, A2, and A3)

(4)

Hall input (H1), H1­, H2), H2­, H3), H3­)

867

Motor driver ICs
(5) Hall bias

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
(7) FR Output

(6)

FG output

(8)

Short brake

Note: Resistance values are typical values.

868

Motor driver ICs

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 5V, VM1 = 12V, VM2 = 12V)

869

Motor driver ICs

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

FCircuit 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.

870

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 reverse 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 reverse rotation detection circuit operates. The output goes OFF, and becomes open circuit.

871

Motor driver ICs

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS
(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 enters power save mode. Also, the Hall bias pins turn on and off with the power save pin.

(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 lowerside output transistors go on. Short braking operates regardless of the torque command signal.

FApplication example

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Motor driver ICs

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

FOperation 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 between ±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 175_C, the A1, A2, and A3 coil outputs go open circuit. The thermal shutdown has approximately 15_C of hysteresis.

FElectrical characteristics curves

873

Motor driver ICs

BA6849FP / BA6849FP-Y / BA6849FM / BA6849FS

FExternal dimensions (Units: mm)

874

Appendix

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. Upon the sale of any such devices, other than for buyer's right to use such devices itself, resell or otherwise dispose of the same, no express or implied right or license to practice or commercially 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.

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. 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.

Appendix1-Rev1.0