Specification

[AP1034]
016003455-E-01 - 13 - 2016/06

Active Decay Mode Current Waveform
The AP1034 selects the decay mode automatically for better current follower performance. Usually, it
operates in slow decay mode but changes to fast decay mode when switching the step during current
decreasing period.
Also There is Pre fast decay mode before Charge mode.
Therefore if in the low target current, it is possible to
reduce the current distortion.
①
②
③
①
②
③
①
②
③
①
④
②
③
①
②
③
①
②
③
Iload (100%)
Chopper Frequency(f
CP
)
Mottor Current
①
Charge
②
Slow decay
③
Pre fast decay
④
Fast decay
Blanking Time (t
B
)
Figure 9. Active Decay Mode Current Waveform

Blanking Time
Recovery current of parasitic diode arises when the decay mode changes charge mode during PWM constant
current operation. It can flow into current sense resistor, and the noise of current sense terminal (IS1,IS2)
cause the malfunction of internal comparator (CMP1,CMP2) . To prevent malfunction, the detection of
current sense comparator is blanking during Charge mode. The blanking time of the IC is 2.6us fixed at FS=L,
1.3us fixed at FS=H.

Output Transistor Operating Mode
●
Charge mode
●
Slow decay mode
●
Pre Fast decay mode
●
Fast decay mode
ON
OFF
OFF
ON
OFF
OFF
ON
ON
OFF
ON
ON
OFF
OFF
OFF
ON
OFF
Figure 10. Current Flow of Mixed Decay Mode