BA6219BFP Datasheet, PDF (6/13 Pages) Rohm – 2.0A or More Reversible Motor Drivers (Single Motor)

BA6219BFP-Y,BA6222
Technical Note
2) Output high voltage setting
This function optionally sets output voltage by the output high voltage setting pin and controls the motor rotating speed.
However, when the output high voltage is set to a low level, consumption at IC increases. Carry out thermal design with
sufficient margin incorporated with the power dissipation (Pd) under the actual application condition taken into account.
a) BA6219BFP-Y
The circuit diagram associated with the output high voltage setting
VR pin is as per shown on the right. The maximum output voltage
V_OMAX is expressed by:
V_OMAX = VCC1 - ( V_SAT(Q1) + V_F(Q2) + V_F(Q3) + V_F(Q4) )
In addition, the relation of VR voltage to output voltage at V_OMAX or lower is
expressed by:
V_OH = VR + ( V_F(Q5) + V_F(Q6) + V_F(Q7) ) - ( V_F(Q2) + V_F(Q3) + V_F(Q4) )
V_OH = VR + ΔV_F ≈ VR
Q1
Q2
Q5
Q6
Q7
Q3
Q4
VR
Fig. 17
VCC1
VCC2
OUT
ΔV_F depends on the output current but is nearly V_OH=VR. (Reference values; V_SAT ≈ 0.25V, V_F ≈ 0.75V)
b) BA6222
As the relationship between the output high voltage setting pin VR
voltage and output high voltage V_OH is expressed by:
V_OH ≈ 4 x VR + V_OFS
In such event, V_OFS means the offset voltage, which varies in accord with
output current and chip temperature.
The VR voltage region can be classified into three categories in accord
with the output state:
(A) Output high voltage 0V offset region
(B) Fourfold gain region
(C) Output voltage saturated region
VOH
VCC1 - 3VF - VSAT
BA6222
BA6219BFP-Y
(A)
(B)
VR
(C)
Fig. 18
Using this function with the VR pin connected to a load which has output impedance of several hundred ohms may
result in oscillation. In such event, connect a capacitor of 3300pF or higher to about 0.1μF across VR and GND
and make sure that the motor is free of oscillation.
c) Power supply voltage range of VR voltage
VOH
When output voltage control pin (VR) is used:
VR < VCC1 - ( V_SAT(Q1) + V_F(Q5) + V_F(Q6) + V_F(Q7) )
VR ≈ VCC1 - 2.5V
VR < VCC2 - ( V_SAT(Q3) - V_F(Q3) - V_F(Q2) ) - ( V_F(Q5) + V_F(Q6) + V_F(Q7) )
VR ≈ VCC2 - 1V
The output voltage control function does not operate in the region
outside this range. In addition, when the VR pin is not used, use
by shorting VR to VCC1.
Control range
VR
Saturation range
Fig. 19
3) 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 L terminal to achieve potential below GND when brake is activated.)
via OPEN: The time longer than 1 ms is recommended.
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2011.05 - Rev.B