AN8480NSB

ICs for Compact Disc/CD-ROM Player

6

s Application Notes (continued)

• Theory of thermal resistance

A chip temperature or the fin temperature can be understood in the same way as Ohm's Law.

P

: Electric power generated by IC

If it exceeds 150

°C, you can suppress the rise of a chip temperature by adding a heat sink which is equivalent to

A package surface and the fin are available for a temperature measurement. But the fin part is recommendable for

measurement because a package surface measurement does not always promise you a consistent measuring result.

s Application Circuit Example

P

ECR

17

18

12

1

26

27

28

22

21

7

9

8

6

5

2

3

Hall

bias

Start/stop

Thermal

protection

circuit

Absolute

value

Brake

circuit

Hall

amp.

matrix

Detection

Upper side

distribution

Lower side

distribution

Logic

Amp.

Amp.

Direction

detection

Direction

changeover

EA

ER

VTL

EP

= ER × EA

FG

comparator

VH

H3

−

H3

+

H2

−

H2

+

H1

−

H1

+

EC

Servo

torque

command

VM

CS1

A1

A2

A3

PG

FG

High: Start

Medium: FG is on.

Low: Stop

Low: Short brake

High: Reverce rotation brake

Low: TSD on

High: TSD off

0.1

µF

FG signal