STK672-400 Datasheet, PDF (13/19 Pages) Sanyo Semicon Device – Thick-Film Hybrid IC 2-phase Stepping Motor Driver

STK672-400
Phase signal ON time T and constant-current control time t2 in excitation modes
(1) 2 phase excitation mode
t2 = (2÷CLOCK) - (t1 + t3)·······························(3-9)
(2) 1-2 phase excitation mode
t2 = (3÷CLOCK) - t1·········································(3-10)
(3) W1-2 mode
t2 = (7÷CLOCK) - t1·········································(3-11)
(4) 2W1-2 phase excitation (4W1-2 phase excitation) t2 = (15÷CLOCK) - t1·······································(3-12)
Enter the value of Vsat and Vdf from Vsat vs IOH and Vdf vs IOH graphs for the set current value of IOH.
Compare the HIC average power loss thus determined with the ΔTc vs Pd graph to determine whether the heat sink is
necessary. See the section on STK672-400 thermal design section later in this document for details on heat sink design.
The value HIC for the average power loss PdAV is the loss when the device is not in the avalanche state. To add the
avalanche state loss, add the STK672-400 avalanche energy allowable value from equation (2) to the PdAV value above.
When the fin is not used, the HIC substrate temperature Tc changes because of the effect of air convection, etc. Be sure
to check temperature rise with the set.
[Calculating PAVL, the average power loss in the avalanche state]
The average power loss in the avalanche state, PAVL, is given by formula (4-2), which is the expression for the loss,
PAVL, in the avalanche state during constant-current chopping operation multiplied by the chopping frequency.
PAVL=VDSS×IAVL×0.5×tAVL×fc ······································································································ (4-2)
fc: Hz (Use the maximum PWM frequency for the STK672-400 series.)
The values for VDSS, IAVL, and tAVL must be observed with an oscilloscope in an actual operating circuit based on
the STK672-400 series device, and those values must then be substituted into these equations.
The PAVL added differs for the different excitation modes: for modes other than 2 phase excitation, multiply PAVL by
the following constant and then add to the hybrid IC internal average power loss.
For 1-2 phase excitation and higher modes: PAVL(1)=0.7×PAVL··················································· (3-13)
For 2 phase excitation mode and motor hold mode: PAVL(1)=1×PAVL·········································· (3-14)
No.A0751-13/19