bd6709fs ROHM Co. Ltd., bd6709fs Datasheet - Page 28

• Manufacturer Part Number: bd6709fs
• Description: Dc Brushless Motor Drivers For Cooling Fans Speed Controllable Single-phase Full-wave Dc Brushless Fan Motor Drivers
• Manufacturer: ROHM Co. Ltd.

6) Hall input setting
○ Reducing the noise of hall signal
Hall input voltage range is shown in operating conditions.
Adjust the value of hall element bias resistor R1 and R2 in Fig.90 so that the input voltage of a hall amplifier is input in
"hall input voltage range" including signal amplitude.
Hall element may be affected by Vcc noise or the like depending on the wiring pattern of board. In this case, place a
capacitor like C1 in Fig.90. In addition, when wiring from the hall element output to IC hall input is long, noise may be
loaded on wiring. In this case, place a capacitor like C2 in Fig.90.
H-
C2
＜ BD6718FV ＞
RH
R1
H+
C1
Hall bias current
= HB / (R1 + RH)
HB
Fig.89 Hall input voltage range
Fig.90 Application near hall signal
28/40
Hall element
＜ BD6709FS 、 BD6721FS 、 BD6722FS ＞
Setting R2=0 ohm is acceptable for
BD6721FS and BD6722FS.
H-
C2
RH
R1
R2
Vcc
Hall input voltage range
upper limit
Hall input voltage range
lower limit
GND
H+
C1
Hall bias current
= Vcc / (R1 + R2 + RH)
Vcc