Data Sheet

TB67S249FTG
2017-08-18
17
• When the next current step/ratio is lower than the previous step
• When the Fast period continues beyond 1 fchop cycle (Current does not reach ADMDth within
1 fchop cycle.)
Timing charts may be simplified for explanatory purpose.
Fast
NF
NF
NF
The current is charged for a short period of time to
be compared in the RS comparator circuit. S
ince
the motor current level is higher than the next
NFth, the
operation will be switched
to Fast mode
instantly.
f
chop
f
chop
f
chop
f
chop
Slow
Fast
Charge
Slow
Fast
Charge
Fast
Slow Slow
Charge
Charge
Internal
OSC
waveform
NFth
ADMDth
NFth
ADMDth
Fast
NF
NF
f
chop
f
chop
f
chop
f
chop
Slow
Fast
Charge
Fast
Charge
Slow Slow
Charge
When
the motor current does not reach the
ADMDth
after 1 fchop cycle, the Fast
recirculating
sequence continues on until the
current level reaches the ADMDth.
Internal
OSC
waveform
NFth
ADMDth
NFth
ADMDth
The current is charged for a short period of time to be
compared in
the NF comparator circuit. Since the
motor current level is higher than the next NFth, the
operation
will be switched to Fast mode instantly.