STK672-432A-E Sanyo Semicon Device, STK672-432A-E Datasheet - Page 17

• Manufacturer Part Number: STK672-432A-E
• Description: 2-phase Stepping Motor Driver
• Manufacturer: Sanyo Semicon Device

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Fixed current control time, t2, for each excitation mode
(1) 2-phase excitation
(2) 1-2 phase excitation
(3) W1-2 phase excitation
(4) 2W1-2 phase excitation (and 4W1-2 phase excitation)
For the values of Vsat and Vdf, be sure to substitute from Vsat vs I OH and Vdf vs I OH at the setting current value I OH .
(See pages to follow)
Then, determine if a heat sink is necessary by comparing with the ΔTc vs Pd graph (see next page) based on the
calculated average output loss, HIC.
For heat sink design, be sure to see STK672-432A-E.
The HIC average power, PdAVex described above, represents loss when not in avalanche mode. To add the loss in
avalanche mode, be sure to add PAVL (4-13, 14) using the formula (3-2) for average power loss , PAVL, for STK672-
4** avalanche mode, described below to PdAVex described above.
When using this IC without a fin, always check for temperature increases in the set, because the HIC substrate
temperature, Tc, varies due to effects of convection around the HIC.
[Calculating the average power loss, PAVL, during avalanche mode]
The allowable avalanche energy, EAVL, during fixed current chopping operation is represented by Equation (3-2) used
to find the average power loss, PAVL, during avalanche mode that is calculated by multiplying Equation (3-1) by the
chopping frequency.
Be sure to actually operate an STK672-4** series and substitute values found when observing operations on an
oscilloscope for V DSS , IAVL, and tAVL.
The sum of PAVL values for each excitation mode is multiplied by the constants given below and added to the average
internal HIC loss equation, except in the case of 2-phase excitation.
PAVL=V DSS ×IAVL×0.5×tAVL×fc ······································································································(3-2)
1-2 excitation mode and higher: PAVL(1)=0.7×PAVL····································································· (4-13)
During 2-phase excitation and motor hold: PAVL(1)=1×PAVL ······················································· (4-14)
fc: Hz units (input MAX PWM frequency when using the STK672-4** series.)
STK672-432A-E
t2 = (2÷CLOCK) - (t1 + t3)·······························(4-9)
t2 = (3÷CLOCK) - t1·········································(4-10)
t2 = (7÷CLOCK) - t1·········································(4-11)
t2 = (15÷CLOCK) - t1·······································(4-12)
No.A1586-17/21
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