Technical Note

8/10

BA6950FS, BA6951FS

www.rohm.com

2011.05 - Rev.C

© 2011 ROHM Co., Ltd. All rights reserved.

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Notes for use

1) Absolute maximum ratings

Devices may be destroyed when supply voltage or operating temperature exceeds the absolute maximum rating.

Because the cause of this damage cannot be identified as, for example, a short circuit or an open circuit, it is important

to consider circuit protection measures – such as adding fuses – if any value in excess of absolute maximum ratings is

to be implemented.

2) Connecting the power supply connector backward

Connecting the power supply in reverse polarity can damage the IC. Take precautions against reverse polarity when

connecting the power supply lines, such as adding an external direction diode.

3) Power supply lines

Return current generated by the motor’s Back-EMF requires countermeasures, such as providing a return current path

by inserting capacitors across the power supply and GND (10µF, ceramic capacitor is recommended). In this case, it is

important to conclusively confirm that none of the negative effects sometimes seen with electrolytic capacitors –

including a capacitance drop at low temperatures - occurs. Also, the connected power supply must have sufficient

current absorbing capability. Otherwise, the regenerated current will increase voltage on the power supply line, which

may in turn cause problems with the product, including peripheral circuits exceeding the absolute maximum rating. To

help protect against damage or degradation, physical safety measures should be taken, such as providing a voltage

clamping diode across the power supply and GND.

4) Electrical potential at GND

Keep the GND terminal potential to the minimum potential under any operating condition. In addition, check to

determine whether there is any terminal that provides voltage below GND, including the voltage during transient

phenomena. When both a small signal GND and high current GND are present, single-point grounding (at the set’s

reference point) is recommended, in order to separate the small signal and high current GND, and to ensure that

voltage changes due to the wiring resistance and high current do not affect the voltage at the small signal GND. In the

same way, care must be taken to avoid changes in the GND wire pattern in any external connected component.

5) Thermal design

Use a thermal design that allows for a sufficient margin in light of the power dissipation (Pd) under actual operating

conditions.

6) Inter-pin shorts and mounting errors

Use caution when positioning the IC for mounting on printed circuit boards. The IC may be damaged if there is any

connection error, or if pins are shorted together.

7) Operation in strong electromagnetic fields

Using this product in strong electromagnetic fields may cause IC malfunctions. Use extreme caution with

electromagnetic fields.

8) ASO - Area of Safety Operation

When using the IC, set the output transistor so that it does not exceed absolute maximum ratings or ASO.

9) Built-in thermal shutdown (TSD) circuit

The TSD circuit is designed only to shut the IC off to prevent thermal runaway. It is not designed to protect the IC or

guarantee its operation in the presence of extreme heat. Do not continue to use the IC after the TSD circuit is activated,

and do not operate the IC in an environment where activation of the circuit is assumed.

10) Capacitor between output and GND

In the event a large capacitor is connected between the output and GND, if VCC and VIN are short-circuited with 0V or

GND for any reason, the current charged in the capacitor flows into the output and may destroy the IC. Use a capacitor

smaller than 0.47μF between output and GND.

11)

Testing on application boards

When testing the IC on an application board, connecting a capacitor to a low impedance pin subjects the IC to stress.

Therefore, always discharge capacitors after each process or step. Always turn the IC's power supply off before

connecting it to or removing it from the test setup during the inspection process. Ground the IC during assembly steps

as an antistatic measure. Use similar precaution when transporting or storing the IC.

12) Switching of rotating direction (FWD/REV)

When the rotating direction is changed over by the motor rotating condition, switch the direction after the motor is

temporarily brought to the BRAKE condition or OPEN condition. It is recommended to keep the relevant conditions as

follows: via BRAKE: Longer than braking time*.

(* the time required for the output voltage to achieve potential below GND when brake is activated.)

via OPEN: The time longer than 1 ms is recommended.