STK6712BMK4 Sanyo Semicon Device, STK6712BMK4 Datasheet - Page 7

• Manufacturer Part Number: STK6712BMK4
• Description: (STK6711AMK4 - STK6714BMK4) 4-Phase Stepping Motor Driver Unipolar Self-Excitation Type(Io = 1.5A)
• Manufacturer: Sanyo Semicon Device

Determining Chopping Frequency
The STK6713BMK4 uses constant current for self-excitation.
The I
As a result, the chopping frequency is
However, note that when the following conditions exist the value for F will change.
Because the STK6712BMK4 is self-exciting there will be minor variation in motor inductance during motor revolution.
Final design verification is required in an actual model.
Thermal Radiation Design
The HIC radiator plate size is dependent on the motor output current I
mode, and excitation input signal clock frequency fclock (Hz).
The thermal resistance for the radiator can be determined from the following expression.
OH
t
F ≈
14 10
t
ON
OFF
c – a =
t
F =
OFF
≈
t
≈ t
ON
R + 0.88
time is set to about 14 µs, and the t
L:
R:
V
I
Tc max = HIC substrate temperature
Ta = set internal temperature
Pd = HIC internal mean power dissipation (W)
t
–6
OFF
OH
ON
CC
+ t
1
Tc max – Ta
L
≥
:
1 + t
+ 14 10
: Motor supply voltage
OFF
–L
R
Motor winding inductance
Motor resistance
Output current
Pd
OFF
In (
=
In (
1
2 = 14 10
V
t
–6
ON
CC
I
OH
+ t
(°C/W).................................................................................................................. (9)
+ 14 10
– ( I
OFF
V
1
R + V
CC
2
OH
-6
+ 0.88
(Hz)........................................................................................................ (8)
+ t
e
–6
CC
–
OFF
R
L
(Hz) ................................................................................................ (6)
+ 0.88
t
OFF
V
CC
ON
–
V
– (R + 0.88) I
STK6712BMK4
time can be expressed as:
) = t
CC
R
+ 0.88
OFF
(°C)
(°C)
2 ............................................................................. (7)
(1 – e
OH
–
OH
R
L
t
OFF
(A), motor electrical characteristics, excitation
)) (R + 0.88)
) ............................ (5)
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