BD64550EFV Ver la hoja de datos (PDF) - ROHM Semiconductor
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BD64550EFV Datasheet PDF : 17 Pages
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BD64550EFV
Technical Note
●H-bridge Driver Operation
This IC has built-in 2-channel H-bridge driver.
Each can be used for DC motor drive independently.
1. Current setting
Motor output current-limit value can be set according to the equation below.
Io=(VREF/10)・(1/RNFS) [A]
Decide within the range VREF = 0.8V to 3.5V, RNFS = 0.04Ωto 0.35Ω.
2. DECAY mode
Current decay mode can be selected from serial input at the time of motor chopping drive.
Each mode and timing is as follows.
○SLOW DECAY mode
○FAST DECAY Mode
○Timing chart
VM
VM
ON→OFF
OFF→OFF ON→OFF
OFF→OFF
01
48
FBASE
(Internal 8 MHz)
Limit value
Output current
OFF→OFF
ON→OＮ OFF→OFF
ON→OFF
At the time on
At the time off (at DECAY)
At the time on
At the time off (at DECAY)
On time
Off time
(Set by off time)
SLOW
FAST
Fig.16 On/Off Timing at SLOW
Fig.17 On/Off Timing at FAST
Fig.18 DECAY Mode Timing Chart
3. Protection area for output current value wrong detection
In order to avoid wrong detection of current detection comparator by varistor current element in each motor, current
detection are masked at the timing as follows.
①PHASE switching time
②ENABLE on time
③When output is on after OFF_TIME is finished at the time of current chopping drive
①PHASE switching time
PHASE signal
Motor current
Mask area
BLANK TIME
Fig.19 Timing Chart of PHASE Switching Time
②ENABLE on time
③Current chopping driving time
ENABLE
Motor current
Mask area
BLANK TIME
Fig.20 Timing Chart of ENABLE On Timing
RNF voltage
Mask area
BLANK TIME
OFF TIME
Fig.21 Timing Chart of Current Chopping Driving Time
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8/16
2010.06 - Rev.A
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