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© 2019 ROHM Co., Ltd.
No.64UG012E Rev.002
April.2021
User’s Guide
BD63xxxEFV-EVK-001
4.5 CR chopping frequency setting ( CR Terminal )
You can set frequency of the output by a capacitor (C0) and resistor (R0) to be connected between CR terminal to GND.
Please connect the external C0 ( 470p to 1500pF ) and R0 ( 10k to 200k
Ω ) between this terminal and GND. This board is
connected with C0 = 1000 pF, R0 = 39 K
Ω. Chopping frequency is set to about 24.5kHz. When it is open or it is biased from
the outside, it is not possible to control normal PWM constant current, so if it is used in PWM constant current control, always
put both C and R parts.
4.6 Current decay mode setting ( MTH Terminal )
Current decay mode can be optionally set according to input voltage for MTH terminal.
( SLOW DECAY / MIX DECAY / FAST DECAY ).
The input voltage of this board can be set with a division level of 5V by the resistor (R17, R16) to be connected between 5V
–
GND. This board does not implement R16, R17. Please adjust it while confirming motor drive. Please connect the capacitor
C34 between MTH terminal - GND when the terminal voltage is unstable. Connect to GND if using at SLOW DECAY mode.
Avoid using with the MTH Terminal open because if the MTH Terminal is open, the input is unsettled, and then there is the
danger that PWM operation becomes unstable. Besides, take into consideration the outflowcurrent (Max2 μA) if the input
used is a resistor divider.
4.7 Output current value setting (VREF Terminal),
Connection terminal of resistor for detecting of output current (RNF1 Terminal,RNF2 Terminal)
This is the terminal to set the output current value. The output current value ( max value ) can be set by VREF voltage
( R20, R21, C4 ) and current-detecting resistor ( RNF resistor, R1, R2, R7, R8 ).
This board does not implement R20, R21, C4.
The VREF terminal input voltage is set with a division level of 5V by the resistance ( R20, R21 ) to be connected between 5V
– GND. Please set the the output current in reference to the following setting method.
Please connect the capacitor C4
between VREF terminal - GND when the terminal voltage is unstable.
And the resistor for detecting of current can be set by R1, R2, R7, R8, this board is connected R1 = R2 = R7 = R8 =0.2
Ω.
＜
How to set output current value
＞
The output current can be set by VREF voltage and resistor for detecting of output current ( RNF resistance ) .
BD63525AEFV, BD63511EFV, BD63521EFV FULL STEP only
Output current I
OUT
[ A ] = { VREF [ V ] / 5 ( division ratio inside IC )
} / (0.7071 x RNF) [ Ω ]
BD63525AEFV, BD63511EFV, BD63521EFV other than FULL STEP
Output current I
OUT
[ A ] = { VREF [ V ] / 5 ( division ratio inside IC )
} / RNF [ Ω ]
Avoid using the VREF Terminal open because input voltage becomes unsettled, and the VREF voltage increases, and then
the set current increases and a large current flows which may cause malfunction. Keep to the input voltage range because if
voltage above 3V is applied on the VREF Terminal, then there is also the danger that a large current flows in the output and
so OCP or TSD will operate. Besides, take into consideration the outflow current (Max 2μA) if the input used is a resistor
divider. The minimum current, which can be controlled by VREF voltage
, is determined by motor coil’s L, R values and
minimum ON time because there is a minimum ON time in PWM drive.
MTH terminal input voltage [V]
Current decay mode
0.0 to 0.3
SLOW DECAY
0.4 to 1.0
MIX DECAY
1.5 to 3.5
FAST DECAY
