LB11847_08 Datasheet, PDF (13/15 Pages) Sanyo Semicon Device – PWM Current Control Type Stepping Motor Driver

LB11847
4. Simultaneous ON prevention function
This IC incorporates a circuit to prevent feedthrough current when phase switching. For reference, the output ON and
OFF delay times at PHASE and ENABLE switching are given below.
Reference data * typical value
PHASE switching
(Low → High)
PHASE switching
(High → Low)
ENABLE switching
ON delay time
OFF delay time
ON delay time
OFF delay time
ON delay time
OFF delay time
Sink side
1.9μs
0.8μs
1.4μs
0.9μs
2.15μs
1.2μs
Source side
2.2μs
1.8μs
1.7μs
1.35μs
2.75μs
5.8μs
5. Noise canceler
This IC has a noise canceling function to prevent malfunction due to noise spikes generated when switching ON. The
noise cancel time tn is determined by internal resistance of the CR pin and the constant of the externally connected CR
components. The constant also determines the switching OFF time.
Figure 1 shows the internal configuration at the CR pin, and Figure 2 shows the CR pin constant setting range.
Equation when logic voltage VCC = 5V
CR pin voltage E1 = VCC • R/(R1+R2+R) [V]
Noise cancel time tn ≈ (R1+R2) • C • 1n {(E1-1.5)/(E1-4.0)} [s]
Switching OFF time toff ≈ –R • C • 1n (1.5/E1) [s]
Internal resistance at CR pin : R1 = 1kΩ, R2 = 300Ω (typ.)
*The CR constant setting range in Figure 2 on page 16 is given for reference. It applies to a switching OFF time in the
range from 8 to 100μs. The switching time can also be made higher than 100μs. However, a capacitor value of more
than several thousand pF will result in longer noise canceling time, which can cause the output current to become
higher than the set current. The longer switching OFF time results in higher output current ripple, causing a drop in
average current and rotation efficiency. When keeping the switching OFF time within 100μs, it is recommended to stay
within the CR constant range shown in Figure 2.
Internal configuration at CR pin
VCC line
One-shot multi-blanking
time circuit
CR pin
E1
R1 1kΩ
R2
300Ω
C:470pF
R:15kΩ
Figure 1
No.6183-13/15