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Motor driver ICs
Reversible motor driver
BA6950FS
The BA6950FS is a reversible-motor driver suited for brush motors. Two logic inputs allow four output modes: forward, reverse, stop (standby), and brake. The rotational speed of motor can be set arbitrarily by changing the voltage applied to the motor with control pins. The IC can also drive a motor at a constant speed by using a built-in current feedback amplifier. FApplications VCRs, audio equipment FFeatures 1) Two logic inputs allow four output modes: forward, reverse, stop (standby), and brake. 2) Motor speed variable with voltage control signals.
3) Built-in current feedback amplifier allows constant motor speed. 4) Control gain can be set arbitrarily by using external resistors. 5) Built-in thermal shutdown circuit.
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating conditions (Ta = 25_C)
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Motor driver ICs
FBlock diagram
BA6950FS
FPin descriptions
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Motor driver ICs
FInput / output circuit (resistances, in , are typical values) (1) R and F inputs (pins 5 and 10)
BA6950FS
(3)
Motor output (pins 6, 7, 8, and 9)
(2)
CTL amplifier (pins 2 and 3)
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Motor driver ICs
FElectrical characteristics (unless otherwise noted, Ta = 25_C, VCC = 4.8V, VB = 4.8V)
BA6950FS
FCircuit operation (1) Input section (FIN, RIN) Control signals are input from these pins. Current flows from M2 to M1 (forward mode) when FIN is HIGH and RIN is LOW, and from M1 to M2 (reverse mode) when RIN is HIGH and FIN is LOW. Putting FIN and RIN both HIGH results in the brake mode in which the high-side output transistor is turned off to shut down the motor driving current and the low-side output transistor is turned ON to absorb the counter-electromotive force of the motor, so that a brake is put on the motor. When FIN and RIN are both LOW, both M1 and M2 are left open and the motor stops. Input / output truth table
(3) Output high level voltage Values of current, voltage, and HIGH level output voltage can be set as follows by using external resistors (refer to the application circuit of Fig. 4). S I16 pin (IRT1) I16 pin (IRT1) = V2 pin/R1 SSS 1 S I15 pin (IRT2) SSS 2 I15 pin (IRT2) = I8 pin R5/R4 S V16 pin (VRT1) V16 pin = R3 (I16 pin)I15 pin))R2 I16 pin
SSS 3 S V7, 9 pin (M1, M2 voltage; high-side voltage) SSS 4 V7, 9 pin = 4 V16 pin (Typ.) (4) Current feedback amplifier The pin-8 current is increased when the motor rotational speed is reduced by loading, and the current feedback amplifier increases the pin-15 current according to equation 2 . Because the pin-16 voltage then increases according to equation 3 , the HIGH level output voltage also increases according to equation 4 . In this way, the rotational speed is kept constant by increasing the voltage applied to the motor.
(2) Output section (M1, M2) Two logic inputs control the motor by changing the status of bridge-configured transistors.
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Motor driver ICs
FApplication example
BA6950FS
Fig.4 FOperation notes (1) Thermal shutdown circuit The thermal shutdown (TSD) circuit turns off all driver outputs when the IC junction temperature rises above 175_C (Typ.). The temperature difference between the activation and deactivation settings is about 20_C. STemperature setting of TSD
(2) Control logic and control signal input pins Voltage should never be applied to the control logic input pins (pins 5 and 10) or the control signal input pin (pin 2) when the VCC voltage is not applied to the IC. Similarly, the voltage on each input pin should not exceed any applied VCC voltage. (3) PCB arrangement When changing the rotational direction of a motor, a large
current of up to a few hundred milliamperes can flow between the motor power supply (pin 6) and RNF (pin 8). Depending on the application, this large output current may flow back to input pins, resulting in output oscillation or other malfunctions. Make sure that your design does not allow a common impedance between the large current output lines and the input section. Suppress the power supply impedance to low levels, otherwise output oscillation may occur. (4) Package power The power dissipated by the IC varies widely with the supply voltage and the output current. Give full consideration to the package power dissipation rating when setting the supply voltage and the output current. (5) The input pins (pins 5 and 10) have temperaturedependent characteristics. Take the temperature effect into consideration when using the IC. (6) To eliminate motor noise, connect a capacitor between M1 (pin 7) and GND and between M2 (pin 9) and GND.
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Motor driver ICs
FElectrical characteristic curves
BA6950FS
FExternal dimensions (Units: mm)
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