STK672-440A-E Datasheet, PDF (16/21 Pages) Sanyo Semicon Device – Thick-Film Hybrid IC 2-phase Stepping Motor Driver

STK672-440A-E
4. Calculating STK672-440A-E HIC Internal Power Loss
The average internal power loss in each excitation mode of the STK672-440A-E can be calculated from the following
formulas. *1
[Each excitation mode]
2-phase excitation mode
2PdAVex= (Vsat+Vdf) ×0.5×CLOCK×IOH×t2+0.5×CLOCK×IOH× (Vsat×t1+Vdf×t3) --------------------------- (4-1)
1-2 Phase excitation mode
1-2PdAVex= (Vsat+Vdf) ×0.25×CLOCK×IOH×t2+0.25×CLOCK×IOH× (Vsat×t1+Vdf×t3) ---------------------- (4-2)
W1-2 Phase excitation mode
W1-2PdAVex=0.64[(Vsat+Vdf) ×0.125×CLOCK×IOH×t2+0.125×CLOCK×IOH× (Vsat×t1+Vdf×t3)] ---------- (4-3)
2W1-2 Phase excitation mode
2W1-2PdAVex=0.64[(Vsat+Vdf) ×0.0625×CLOCK×IOH×t2+0.0625×CLOCK×IOH× (Vsat×t1+Vdf×t3)] ------ (4-4)
4W1-2 Phase excitation mode
4W1-2PdAVex=0.64[(Vsat+Vdf) ×0.0625×CLOCK×IOH×t2+0.0625×CLOCK×IOH× (Vsat×t1+Vdf×t3)] ------ (4-5)
Motor hold mode
HoldPdAVex= (Vsat+Vdf) ×IOH---------------------------------------------------------------------------------------------- (4-6)
Note: 2-phase 100% conductance is assumed in Equation (4-6).
Vsat: Combined voltage of Ron voltage drop + current detection resistance
Vdf: Combined voltage of the FET body diode + current detection resistance *1
CLOCK: Input CLOCK (HIC: input frequency at Pin 12)
*1 Although a synchronous rectification system is used, substitute using the value of Vdf, while taking design
margins into account.
t1, t2, and t3 represent the waveforms shown in the figure below.
t1: Time required for the winding current to reach the set current (IOH)
t2: Time in the constant current control (PWM) region
t3: Time from end of phase input signal until inverse current regeneration is complete
IOH
0A
t1
t2
t3
Motor COM Current Waveform Model
t1= (-L/(R+0.25)) In (1-(((R+0.25)/VCC) ×IOH)) --------------------------------------------------------------- (4-7)
t3= (-L/R) In ((VCC+1)/(IOH×R+VCC+1)) --------------------------------------------------------------------- (4-8)
VCC: Motor supply voltage (V)
L: Motor inductance (H)
R: Motor winding resistance (Ω)
IOH: Motor set output current crest value (A)
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