NJM3517D2 参数 Datasheet PDF下载

NJM3517

Power return T O C for unipolar drive (figure 15)

Relatively high V

Z

gives:

— Relatively fast current decay

— Energy returned to power supply

— Only small energy losses

— Winding leakage flux must be considered

— Potential cooling problems

Power return to T O C for bi-level drive (figure 16)

—

—

—

—

Very fast current decay

Energy returned to power supply

Only small energy losses

Winding leakage flux must be considered

s

DIAGRAMS

How to use the diagrams:

1. What is the maximum motor current in the application?

• The ambient temperature sets the maximum allowable power dissipation in the IC, which relates to the

motor currents and the duty cycle of the Bi-level function. For NJM3517, without any measures taken to

reduce the chip temperature via heatsinks, the power dissipation vs. temperature follows the curve in figure

18.

• Figures 23 and 24 give the relationship between motor currents and their dissipations. The sum of these

power dissipations must never exceed the previously-established value, or life expectancy will be drastically

shortened.

• When no Bi-level or voltage doubling is utilized, the maximum motor current can be found directly in figure

23 .

2. How to choose timing components.

• Figure 21 shows the relationship between C

T

, R

T

, and t

On

. Care must be taken to keep the t

On

time short,

otherwise the current in the winding will rise to a value many times the rated current, causing an overheated

IC or motor.

3. What is the maximum t

On

pulse-width at a given frequency?

• Figure 22 shows the relationship between duty cycle, pulse width, and step frequency. Check specifications

for the valid operating area.

4. Figures 17, 18 and 20 show typical saturation voltages vs. output current levels for different output transistors.

5. Shaded areas represent operating conditions outside the safe operating area.

The specifications on this databook are only

given for information , without any guarantee

as regards either mistakes or omissions. The

application circuits in this databook are

described only to show representative usages

of the product and not intended for the

guarantee or permission of any right including

the industrial rights.