UTCTDA2003

LINEAR INTEGRATED CIRCUIT

8

QW-R107-002,A

THERMAL SHUT-DOWN

The presence of a thermal limiting circuit offers the following advantages:

1).an overload on the output (even if it is permanent),or an excessive ambient temperature can be easily withstood.

2).the heat-sink can have a smaller factor compared with that of a conventional circuit. There is no device damage in

case of excessive junction temperature: all that happens is that Po ( and there Ptot) and Id are reduced.

APPLICATION SUGGESTION

The recommended values of the components are those shown on application circuit of Fig.16. Different values can be

used. The following table can help the designer.

COMPONENT

RECOMMENDED

VALUE

PURPOSE

LARGE THAN

RECOMMENDED

VALUE

LARGE THAN

RECOMMENDED

VALUE

R1

(Gv-1)*R2

gain setting.

increase of Gain

R2

2.2

π

gain and SVR

setting.

Decrease of SVR

R3

1

Ω

Frequency stability

Danger of oscillation

at high frequencies

with inductive loads.

Rx

≈20R2

Upper frequency

cutoff

Poor high frequencies

attenuation

Dange of oscillation

C1

2.2

µF

Input DC decoupling

Noise at switch-on

switch-off

C2

470

µF

Ripple rejection

Decrease of SVR

C3

0.1

µF

Supply voltage

bypass

Dange of oscillation

C4

100

µF

Supply voltage

bypass

Higher low frequency

cutoff

C5

0.1

µF

Frequency stability

Danger of oscillation

at high frequencies

with inductive loads.

Cx

≈1/(2π*B*R1)

Upper frequency

cutoff

smaller bandwidth

Larger bandwidth