L9700 Ver la hoja de datos (PDF) - STMicroelectronics

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L9700

HEX PRECISION LIMITER

STMicroelectronics 

L9700

Figure 2 : Dynamical Input Characteristics (continued) .

2b

solete Product(s) APPLICATION INFORMATION

b Most integrated circuits, both HNMOS and bipolar,

O are very sensitive to positive and negative overvol-

) - tages on the supply and at the inputs.

t(s These transients occur in large numbers and with

different magnitudes in the automotive environment,

uc making adequate protection for devices ai-med at it

d indispensible.

ro Overvoltages on the supply line are faced through

P high voltage integration technologies or through ex-

ternal protection (transil, varistor).

te Signal inputs are generally protected using clamp

le diodes to the supply and ground, and a current limi-

o ter resistor. However, such solutions do not always

bscompletely satisfy the protection specifications in

terms of intervention speed, negative clamping and

Ocurrent leakage high enough to change analog si-

clamp and a low current leakage providing the opti-

mal solution to the problems of the automotive en-

vironment.

The high intervention speed, due to the pre-bias of

the limiter stage and internal feedback, limits the

voltage overshoot and avoid the use of external ca-

pacitors for the limitation of the transient rise times.

Figure 3 illustrates a typical automotive application

scheme. The resistor RS limits the input current of

the device and is therefore dimensioned considering

the characteristics of the transients to be eliminated.

Consequently :

Vtransient Peak

RS = IIN MAX

gnals.

The CIN capacitors must be used only on analog in-

The L9700 device combines a high intervention puts because they present a low impedance during

speed with a high precision positive and negative the sampling period.

4/8

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