16. Techniques for measuring IC internal temperature increases

• Thermocouple measurement

When using a thermocouple for temperature measurement, the thermocouple is attached to a fin on the heat sink.

While this measurement technique is simple, it suffers from large measurement errors when the thermal

generation process is not at steady state.

• Measurement using IC internal diode properties

We recommend using the properties of the parasitic diode that exists between INT.IN and ground for measuring

the temperature of this IC. (Sanyo data: For ID = 1 mA, the temperature characteristic is about 1.8 mV/°C.) The

external resistor must be disconnected when measuring the temperature.

17. Servo constants

The servo constant calculations depend strongly on the characteristics of the motor used and require special expertise.

Normally, the motor manufacturer will set up these constants. Sanyo can provide the data required for the servo

constant calculations. This data includes both the characteristics data for this IC as well as the frequency

characteristics simulation data for the filter characteristics set up by the motor manufacturer.

If the resistor (R10) between DOUT and INT.IN is too small, then C8 and C9 will become excessively large, and if

R10 is too large, then speed errors due to the speed discriminator shutoff current and the integrator input current will

become more likely to occur. Therefore, this resistor should have a value in the range 10 to 100 k

Ω. If the resistor

state pull-in characteristics will be degraded. Thus the value of this resistor must not be made too small. We

recommend a value of around 1 M

Ω when R10 is 75 kΩ. Applications must be designed by first setting up only the

speed discriminator system (R9, R10, C8, and C9) and only then setting up the PLL system resistor R8.

No. 5679-8/10

LB1922