BA6247(2011) 데이터 시트보기 (PDF) - ROHM Semiconductor
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BA6247 Datasheet PDF : 14 Pages
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BA6247FP-Y,BA6238A
Technical Note
2) Output high voltage setting
This function optionally sets output voltage by the VR 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. Please do not to
exceed the VCC1 and VCC2 voltage forced to the VR pin voltage.
a) BA6247FP-Y
The circuit diagram associated with the output high voltage setting VR pin is as per shown on the right.
The output high and low voltages VOH and VOL are expressed by:
VOH = VR + ( VF(Q5) + VF(Q4) ) - ( VF(Q2) + VF(Q3) )
VOH ≈ VR
Q1
Q2
VCC1
VCC2
VOL = VSAT(Q7) + VF(Q6)
Q4
Q3
(Reference values; VSAT ≈ 0.2V, VF ≈ 0.7V)
Q5
Q7
OUT
In addition, the relation of VREF voltage to output voltage
is expressed by:
Q6
VR
GND
VR < VCC1 - VSAT(Q1) - VF(Q4) - VF(Q5)
VR < VCC2 - VSAT(Q3) + (VF(Q2) +VF(Q3)) - ( VF(Q4) + VF(Q5) )
Fig.13 BA6247FP-Y
Therefore, when the VR voltage condition is as follows, the output high voltage is restricted.
VR > VCC1 - VSAT(Q1) - VF(Q4) - VF(Q5)
VR > VCC2 - VSAT(Q3) + (VF(Q2) +VF(Q3)) - ( VF(Q4) + VF(Q5) )
VOH = VCC1 - VSAT(Q1) - VF(Q2) - VF(Q3)
VOH = VCC2 - VSAT(Q3)
b) BA6238A
The circuit diagram associated with the output high voltage setting VR pin is as per shown on the right.
The output high and low voltages VOH and VOL are expressed by:
VOH = VR + ( VF(Q5) + VF(Q4) ) - ( VF(Q2) + VF(Q3) )
VOH ≈ VR
VOL = VSAT(Q7) + VF(Q6)
(Reference values; VSAT ≈ 0.1V, VF ≈ 0.7V)
In addition, the relation of VREF voltage to output voltage is expressed by:
VR < VCC1 - VSAT(Q1) - VF(Q4) - VF(Q5)
VR < VCC2 - ( VSAT(Q2) + VF(Q3) ) + (VF(Q2) + VF(Q3)) - ( VF(Q4) + VF(Q5) )
Therefore, when the VREF voltage condition is as follows, the output high
voltage is restricted.
VR > VCC1 - VSAT(Q1) - VF(Q4) - VF(Q5)
VR > VCC2 - ( VSAT(Q2) + VF(Q3) ) + (VF(Q2) + VF(Q3)) - ( VF(Q4) + VF(Q5) )
Q1
Q4
Q5
VR
Q2
Q3
Q7
Q6
VCC1
VCC2
OUT
GND
Fig.14 BA6238A
VOH = VCC1 - VSAT(Q1) - VF(Q2) - VF(Q3)
VOH = VCC2 - VSAT(Q2) - VF(Q3)
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7/11
2011.05 - Rev.B
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