LM9076 datasheet(6/8 Pages) NSC

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Application Information (Continued)

RESET DELAY TIME

When the regulator output is switched On, or after recovery

from brief V

OUT fault condition, the RESET flag can be can

be programmed to remain low for an additional delay time.

This will give time for any system reference voltages, clock

signals, etc., to stabilize before the micro-controller resumes

normal operation.

This delay time is controlled by the capacitor value on the

DELAY pin. During normal operation the CDELAY capacitor is

charged to near V

OUT . When a VOUT fault causes the

RESET pin to go low, the C

DELAY capacitor is quickly dis-

charged to ground. When the V

OUT fault is removed, and

OUT returns to the normal operating value, the CDELAY

capacitor begins charging at a typical constant 0.420uA rate.

When the voltage on the C

DELAY capacitor reaches the same

potential as the V

OUT pin the RESET pin will be allowed to

return high.

The typical RESET delay time can be calculated with the

following formula:

DELAY =VOUT X(CDELAY /IDELAY )

ForaC

DELAY

value of 0.001uF and a I

DELAY

value of

0.475uA the typical RESET delay time is:

DELAY =VOUT X (0.001uF / 0.475uA)

DELAY = 5.0V X (0.001uF / 0.420uA) = 11.9ms

THERMAL PROTECTION

Device operational range is limited by the maximum junction

temperature (T

J). The junction temperature is influenced by

the ambient temperature (T

A), package selection, input volt-

age (V

IN), and the output load current. When operating with

maximum load currents the input voltage and/or ambient

temperature will be limited. When operating with maximum

input voltage the load current and/or the ambient tempera-

ture will be limited.

Even though the LM9076 is equipped with circuitry to protect

itself from excessive thermal dissipation, it is not recom-

mended that the LM9076 be operated at, or near, the maxi-

mum recommended die junction temperature (T

J) as this

may impair long term device reliability.

The thermal protection circuity monitors the temperature at

the die level. When the die temperature exceeds typically

160C the voltage regulator output will be switched off.

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