SD1579 Datasheet, PDF (6/7 Pages) Silan Microelectronics Joint-stock – Hall IC Fan Motor Driver

APPLICATION INFORMATION
1. Back electromotive force causes regenerated current to VDD line, therefore take a measure such as placing
a capacitor between power supply and GND for routing regenerated current; In order to reduce the output
DO and DOB side effects of induced electromotive force, need to increase a resistance-capacitance
network at the output; in a typical application circuit diagram, R1 and R2 is typically 56 ohms; C1, C2 and
C3 is typically 2.2uF; The value of R and C must match the actual coil;
2. Figure 2 is the normal working state, the current compose ICC and Iload , power dissipation PC = VDD * ICC
+ Vo * Iload , Where Vo is the output voltage when DO or DOB turn on; It is need to be careful not to exceed
its maximum power dissipation value dule to change of power supply voltage VDD and the coil current Iload.
3. SD1579 has built-in reverse protection diodes, so D1 is no need; If you increase the D1 can better protect
the chips, as shown in Figure 3; it should be noted that care should to taken to the two coils current when
power voltage reversed, if 2*Vo * Iload > IC's power consumption, it may cause damage to IC;
Fig.2 Normal working state
Fig.3 Reverse voltage state
4. Add a diode to coils can better protect the chip and the fans at reverse voltage state, as shown in Figure 4;
Figure 4 Add a diode to coils
HANGZHOU SILAN MICROELECTRONICS CO.,LTD
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