BA6285AF 데이터 시트보기 (PDF) - ROHM Semiconductor
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BA6285AF Datasheet PDF : 18 Pages
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BA6956AN,BA6287F,BA6285FS,BA6285AFP-Y,BA6920FP-Y
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) BA6287F, BA6285FS, BA6285AFP-Y
The circuit diagram associated with the output high voltage setting
VREF pin is as per shown on the right. The output high and low
voltages VOH and VOL are expressed by:
VOH = VREF - ( VSAT(Q1) + VF(Q2) )
VOL = VSAT(Q3)
(Reference values; VSAT ≈ 0.15V, VF ≈ 0.7V)
In addition, the relation of VREF voltage to output voltage is expressed by:
( VSAT(Q1) + VF(Q2) ) < VREF < VM - VSAT(Q2) + VF(Q2) + VSAT(Q1)
Fig.35
Q1
Q2
VM
VREF
OUT
Q3
RNF
(GND, BA6287F)
BA6287F, BD6285FS, BA6285AFP-Y
Therefore, when the VREF voltage condition is as follows, the
output high voltage is restricted.
VREF > VM - VSAT(Q2) + VSAT(Q1) + VF(Q2)
VOH = VM - VSAT(Q2)
b) BA6956AN, BA6920FP-Y
The circuit diagram associated with the output high
voltage setting VREF pin is as per shown on the right.
The output high and low voltages VOH and VOL are
expressed by:
VM
VCC
Q1
Q2
Q4
Q3
VM
VCC
Q1
Q2
Q4
Q3
VOH = VREF + ( VF(Q5) + VF(Q4) ) - ( VF(Q2) + VF(Q3) )
VOH ≈ VREF
VOL = VSAT(Q6) (BA6956AN)
VOL = VSAT(Q7) + VF(Q6) (BA6920FP-Y)
(Reference values; VSAT ≈ 0.15V, VF ≈ 0.7V)
VREF
Q5
The output high voltage controllable range is expressed by:
Fig.36
OUT
VREF
Q6
RNF
Q5
Q7
OUT
Q6
RNF
BA6956AN
Fig.37 BA6920FP-Y
VREF < VCC - VSAT(Q1) - VF(Q4) - VF(Q5)
VREF < VM - ( VSAT(Q2) + VF(Q3) ) + ( VF(Q2) + VF(Q3)) - ( VF(Q4) + VF(Q5) ) (BA6956AN)
VREF < VM - VSAT(Q3) + ( VF(Q2) + VF(Q3)) - ( VF(Q4) + VF(Q5) ) (BA6920FP-Y)
When the VREF voltage condition is as follows, the output high voltage is restricted.
VREF > VCC - VSAT(Q1) - VF(Q4) - VF(Q5)
VREF > VM - ( VSAT(Q2) + VF(Q3) ) + ( VF(Q2) + VF(Q3)) - ( VF(Q4) + VF(Q5) ) (BA6956AN)
VREF > VM - VSAT(Q3) + ( VF(Q2) + VF(Q3)) - ( VF(Q4) + VF(Q5) ) (BA6920FP-Y)
VOH = VCC - VSAT(Q1) - VF(Q2) - VF(Q3)
VOH = VM - VSAT(Q2) - VF(Q3) (BA6956AN)
VOH = VM - VSAT(Q3) (BA6920FP-Y)
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12/17
2011.05 - Rev.B
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