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L4979MD L4979D

Note:

1. see fig4 (behavior of output current versus regulated voltage Vo)

2. guaranteed by design

3. When Vo becomes lower than 4V, the reset reaction time decreases down to 2

µs assuring a faster reset condition in this particular

case.

2

VOLTAGE REGULATOR

The voltage regulator uses a p-channel MOS transistor as a regulating element. With this structure a low drop-

out voltage at current up to 150mA is achieved. The output voltage is regulated up to transient input supply volt-

age of 40V. No functional interruption due to over-voltage pulses is generated. The high precision of the output

voltage is obtained with a pre-trimmed reference voltage. A short circuit protection to GND is provided.

Figure 4. Behavior of output current versus regulated voltage Vo (see a.m. Note 1)

3

RESET

guaranteed for an output voltage Vo greater than 1V.

When the output voltage becomes higher than Vo_th then Res goes high with a delay trd. This delay is obtained

by 512 periods of an oscillator (see fig. 5). The oscillator period is given by:

Charge current

4

7.5

14

µA

Discharge current

1.0

2.4

4.5

µA

Watchdog period

25

50

90

ms

Watchdog output low time

6

10

22

ms

ENABLE

Enable input low voltage

1

V

Enable input high voltage

3

V

Enable input hysteresis

700

1000

1100

mV

Pull down current

2

10

20

µA

Pin

Symbol

Parameter

Test Condition

Min.

Typ.

Max.

Unit

Vo

Vo_ref

Iout

Ishort Ilim

Vo

Vo_ref

Iout

Ishort Ilim

ELECTRICAL CHARACTERISTICS (continued)