BD6220F-E2 Datasheet, PDF (16/25 Pages) Rohm – DC Brush Motor Drivers

BD622xxx Series
Operational Notes – continued
12. Regarding the Input Pin of the IC
This monolithic IC contains P+ isolation and P substrate layers between adjacent elements in order to keep them
isolated. P-N junctions are formed at the intersection of the P layers with the N layers of other elements, creating a
parasitic diode or transistor. For example (refer to figure below):
When GND > Pin A and GND > Pin B, the P-N junction operates as a parasitic diode.
When GND > Pin B, the P-N junction operates as a parasitic transistor.
Parasitic diodes inevitably occur in the structure of the IC. The operation of parasitic diodes can result in mutual
interference among circuits, operational faults, or physical damage. Therefore, conditions that cause these diodes to
operate, such as applying a voltage lower than the GND voltage to an input pin (and thus to the P substrate) should
be avoided.
Resistor
Transistor (NPN)
Pin A
Pin A
Pin B
C
B
E
Pin B
P⁺
N
N
Parasitic
Elements
P
P⁺
N
N
P Substrate
GND
Parasitic
Elements
N ^P+
N _{P N P}⁺ _N
P Substrate
Parasitic
GND GND
Elements
Figure 44. Example of monolithic IC structure
B
N Region
close-by
C
E
Parasitic
Elements
GND
13. Area of Safe Operation (ASO)
Operate the IC such that the output voltage, output current, and power dissipation are all within the Area of Safe
Operation (ASO).
14. Power supply lines2
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.
15. Capacitor Between Output and Ground
If a large capacitor is connected between the output pin and ground pin, current from the charged capacitor can flow
into the output pin and may destroy the IC when the VCC or VIN pin is shorted to ground or pulled down to 0V. Use a
capacitor smaller than 10µF between output and ground.
16. Switching Noise
When the operation mode is in PWM control or VREF control, PWM switching noise may affect the control input pins
and cause IC malfunctions. In this case, insert a pull down resistor (10kΩ is recommended) between each control
input pin and ground.
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TSZ02201-0P2P0B300080-1-2
09.Sep.2014 Rev.003