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Motor driver ICs
Three-phase motor driver for CD-ROMs
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
The BA6858A and BA6859A series are ICs developed for CD-ROM spindle motor drives. In addition to the functions of the BA6849 series, (short brake, reverse-rotation prevention circuit, rotation direction dector, and FG output), the BA6858A and BA6859A series have a built-in brake mode switching pin. With torque command input, these series are compatible with the DSP3.3V. In addition, the BA6858A series has an FG composite output. FApplications CD-ROM, CD-R, CD-RW, DVD-ROM, and DVD-RAM FFeatures 1) Three-phase, 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. FAbsolute maximum ratings (Ta = 25_C)
6) 7) 8) 9)
Built-in reverse rotation prevention circuit. Built-in short brake pin. Built-in brake mode switching pin. DSP3.3V compatible.
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FRecommended operating conditions (Ta = 25_C)
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
FBlock diagram
BA6858AFP / BA6858AFM
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FPin descriptions BA6858AFP / BA6858AFM
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
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BA6859AFP / BA6859AFM
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
BA6859AFP-Y
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BA6859AFS
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
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FInput / output circuits (1) Power save
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
(2)
Torque command input
(3)
Torque output (A1, A2, and A3)
(4)
Hall input (H1), H1*, H2), H2*, H3), H3*)
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(5) Hall bias (7)
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
FG2 Output
(6)
FG output
(8)
FR output
(9)
Short brake
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(10) Brake mode
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 5V, VM = 12V)
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BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
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BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
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.11. 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.
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BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
(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 = 0.35 / 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.13. (1) Forward (EC < ECR) The phase relationship between the Hall input signals H2) and H3) becomes as shown in Fig.11, 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.
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(4) Short brake When 2.5V or more is applied to the short brake pin, the top-side output transistors of all phases go off, and the bottom-side output transistors go on. This applies braking to the motor. Short braking operates regardless of the torque command signal. (5) Brake mode switching When 2.5V or more is applied to the BR pin, the brake mode for when EC > ECR can be changed.
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
(6) Power save When 2.5V or more is applied to the power save pin, all circuits are on. When 1.0V or less is applied, the IC enters power save mode, and functions only for surpressing power consumption.
FApplication example
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FOperation notes (1) Torque command
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
When operating with ECR = 2.5V, the voltage range for the torque command input is 0.5V to 3.3V, and therefore, the characteristic will be unbalanced as shown in Fig.15. Take due care.
(2) Switches The switches have a temperature characteristic of approximately -5mV / _C. Take care with regard to the input voltage range. (3) 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.
Set the Hall input voltage in the range 1.0V to 4.0V. Set the resistance values between VH and VCC pins and the Hall elements after calculating the current to flow in Hall elements. If there will not be a resistor connected between the Hall elements and the VH pin, we recommend that IVH = 5mA or more. (4) Thermal shutdown (TSD) When the junction temperature reaches 175_C (Typ.), the A1, A2, and A3 coil outputs go open circuit. The thermal shutdown has approximately 15_C (Typ.) of hysteresis.
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FElectrical characteristics curves
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
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FExternal dimensions (Units: mm)
BA6858AFP / BA6858AFM / BA6859AFP / BA6859AFP-Y / BA6859AFM / BA6859AFS
862

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