LB1824 データシートの表示（PDF） - SANYO -> Panasonic

部品番号

コンポーネント説明

メーカー

LB1824

Power Brushless Motor Driver for OA Equipment

SANYO -> Panasonic 

LB1824

• C1 and C2

C1 and C2 are required for fixed voltage power supply stabilization. Since this IC adopts a direct PWM method

and a large current is switched at the output, noise is generated extremely easily. Accordingly, adequate

stabilization is required on the power supplies so that noise does not cause incorrect circuit operation.

The connections between C1, C2 and C3 and ground should be kept as short as possible. Special care should be

exercised with respect to C1, since its characteristics are easily influenced by grounding problems.

12. External resistors

• R4 and R5

R4 and R5 are used to apply a high level to the F/R pin. Since there is a pull-down resistance of about 50 kΩ on

the F/R input pin it goes low when open. A high level input to the F/R pin should be at least 4.0 V and not more

than 6.3 V.

• R15

R15 is used to apply a high level to the S/S pin. Since there is a pull-down resistance of about 50 kΩ on the S/S

input it goes low when open. (In the start state a high level input to the S/S pin should be at least 4.0 V and not

more than 6.3 V.) As is the case with the F/R pin, the resistance is divided into 2 resistors, and while this scheme

is resistant to noise (since the input impedance can be lowered), if noise is not a

problem the high level can be set by connecting a single resistor such as R15. (A value of 180 kΩ is

recommended.)

If the initial rise in VCC is slow (under about 10 V/ms) the motor may turn to some extent (in stop mode) when

VCC is first applied. This is because the S/S input voltage is resistor divided, and when VCC is under 12 V, the

input voltage will be under 2.6 V (the start input level). If the rise slope cannot be increased and this phenomenon

is a problem, it can be handled by connecting a capacitor between VCC and S/S.

13. Through currents due to the direct PWM method

In the direct PWM method through currents flow in the outputs due to the switching, e.g., when used in a discrete

structure or in LB1822 applications. This is due to the output transistor’s delay and parasitic capacitance. Previously,

an external capacitor was used to handle this kind of situation. However, the LB1824 provides internal circuit

measures to handle this problem, and no measures based on external components are required. Although an overshoot

with a duration of under 10 ns will appear on the RF voltage waveform during switching, this will not be a problem.

14. Oscillator

A crystal oscillator is normally used with the LB1824. If the speed control conditions are not critical, a ceramic

oscillator could be used. To avoid problems always consult the oscillator’s manufacturer concerning the oscillator

itself and the external resistances and capacitances used.

15. IC internal power dissipation calculation example (calculation for a VCC of 24 V and typical ratings)

• Power dissipation due to the power supply current (ICC)

At start time:

P1 = VCC × ICC1 = 24 × 34 m = 0.82 W

At stop time:

P2 = VCC × ICC2 = 24 × 8 m = 0.19 W

• Power dissipation when a –10 mA load current is taken from the 7 V fixed voltage output

P3 = (VCC – 7) × 10 m = 17 × 10 m = 0.17 W

• Power dissipation due to the output drive current (for an output on duty of 100%)

P4 = {(VCC – 1)2/8 k}+{(VCC – 2)2/10 k}

= (232/8 k) + (222/10 k) = 0.12 W

• Power dissipation in the output transistor (For IO = 2 A and an output on duty of 100%)

P5 = VOsat2 × IO = 2.7 × 2 = 5.4 W

Therefore the IC overall power dissipation is:

At stop time:

No. 4264-8/9

Share Link: