bd6222 ROHM Co. Ltd., bd6222 Datasheet - Page 10

• Manufacturer Part Number: bd6222
• Description: H-bridge Drivers For Brush Motors
• Manufacturer: ROHM Co. Ltd.

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BD6220, BD6221, BD6222, BD6225, BD6226, BD6227
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2009 ROHM Co., Ltd. All rights reserved.
e) f) PWM control mode
g) h) VREF control mode
The rotational speed of the motor can be controlled by the switching duty when the PWM signal is input to the FIN
pin or the RIN pin. In this mode, the high side output is fixed and the low side output does the switching,
corresponding to the input signal. The switching operates by the output state toggling between "L" and "Hi-Z".
The PWM frequency can be input in the range between 20kHz and 100kHz. Note that control may not be attained
by switching on duty at frequencies lower than 20kHz, since the operation functions via the stand-by mode. Also,
circuit operation may not respond correctly when the input signal is higher than 100kHz. To operate in this mode,
connect the VREF pin with VCC pin. In addition, establish a current path for the recovery current from the motor, by
connecting a bypass capacitor (10µF or more is recommended) between VCC and ground.
The built-in VREF-switching on duty conversion circuit provides switching duty corresponding to the voltage of the
VREF pin and the VCC voltage. The function offers the same level of control as the high voltage output setting
function in previous models. The on duty is shown by the following equation.
DUTY ≈ VREF [V] / VCC [V]
For example, if VCC voltage is 12V and VREF pin voltage is 9V, the switching on duty is about 75 percent. However,
please note that the switching on duty might be limited by the range of VREF pin voltage (Refer to the operating
conditions, shown on page 2). The PWM carrier frequency in this mode is 25kHz (nominal), and the switching
operation is the same as it is the PWM control modes. When operating in this mode, do not input the PWM signal to
the FIN and RIN pins. In addition, establish a current path for the recovery current from the motor, by connecting a
bypass capacitor (10µF or more is recommended) between VCC and ground.
OUT1
OUT2
VREF
OUT1
OUT2
VCC
RIN
RIN
FIN
FIN
0
OFF
ON
Control input : H
Fig.38 PWM control operation (output stage)
Fig.40 VREF control operation (timing chart)
Fig.39 PWM control operation (timing chart)
M
OFF
ON
10/15
OFF
ON
Control input : L
M
OFF
OFF
Technical Note
2009.04 - Rev.B