bd6709fs ROHM Co. Ltd., bd6709fs Datasheet - Page 39

• Manufacturer Part Number: bd6709fs
• Description: Dc Brushless Motor Drivers For Cooling Fans Speed Controllable Single-phase Full-wave Dc Brushless Fan Motor Drivers
• Manufacturer: ROHM Co. Ltd.

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10) Testing on application boards
11) GND wiring pattern
12) Capacitor between output and GND
13) IC terminal input
14) In use
Cautions on use
1) Absolute maximum ratings
2) Connecting the power supply connector backward
3) Power supply line
4) GND potential
5) Thermal design
6) Inter-pin shorts and mounting errors
7) Actions in strong electromagnetic field
8) ASO
9) Thermal shut down circuit
An excess in the absolute maximum rations, such as supply voltage, temperature range of operating conditions, etc., can
break down the devices, thus making impossible to identify breaking mode, such as a short circuit or an open circuit. If
any over rated values will expect to exceed the absolute maximum ratings, consider adding circuit protection devices,
such as fuses.
Connecting of the power supply in reverse polarity can damage IC. Take precautions when connecting the power supply
lines. An external direction diode can be added.
Back electromotive force causes regenerated current to power supply line, therefore take a measure such as placing a
capacitor between power supply and GND for routing regenerated current. And fully ensure that the capacitor
characteristics have no problem before determine a capacitor value. (when applying electrolytic capacitors, capacitance
characteristic values are reduced at low temperatures)
The potential of GND pin must be minimum potential in all operating conditions. Also ensure that all terminals except GND
terminal do not fall below GND voltage including transient characteristics. However, it is possible that the motor output
terminal may deflect below GND because of influence by back electromotive force of motor. Malfunction may possibly
occur depending on use condition, environment, and property of individual motor. Please make fully confirmation that no
problem is found on operation of IC.
Use a thermal design that allows for a sufficient margin in light of the power dissipation(Pd) in actual operating conditions.
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.
Use caution when using the IC in the presence of a strong electromagnetic field as doing so may cause the IC to
malfunction.
When using the IC, set the output transistor so that it does not exceed absolute maximum rations or ASO.
The IC incorporates a built-in thermal shutdown circuit (TSD circuit). Operation temperature is 175℃(typ.) and has a
hysteresis width of 25℃(typ.). When IC chip temperature rises and TSD circuit works, the output terminal becomes an
open state. 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. Do not continue to use the IC after operation this circuit or use the IC in an environment where
the operation of this circuit is assumed.
When testing the IC on an application board, connecting a capacitor to a pin with low impedance subjects the IC to stress.
Always discharge capacitors after each process or step. Always turn the IC’s power supply off before connecting it to or
removing it from a jig or fixture during the inspection process. Ground the IC during assembly steps as an antistatic
measure. Use similar precaution when transporting or storing the IC.
When using both small signal and large current GND patterns, it is recommended to isolate the two ground patterns,
placing a single ground point at the ground potential of application so that the pattern wiring resistance and voltage
variations caused by large currents do not cause variations in the small signal ground voltage. Be careful not to change
the GND wiring pattern of any external components, either.
When a large capacitor is connected between output and GND, if Vcc is shorted with 0V or GND for some cause, it is
possible that the current charged in the capacitor may flow into the output resulting in destruction. Keep the capacitor
between output and GND below 100uF.
When Vcc voltage is not applied to IC, do not apply voltage to each input terminal. When voltage above Vcc or below
GND is applied to the input terminal, parasitic element is actuated due to the structure of IC. Operation of parasitic
element causes mutual interference between circuits, resulting in malfunction as well as destruction in the last. Do not
use in a manner where parasitic element is actuated.
We are sure that the example of application circuit is preferable, but please check the character further more in application
to a part which requires high precision. In using the unit with external circuit constant changed, consider the variation of
externally equipped parts and our IC including not only static character but also transient character and allow sufficient
margin in determining.
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