l4979md13tr STMicroelectronics, l4979md13tr Datasheet - Page 5

• Manufacturer Part Number: l4979md13tr
• Description: Low Drop Voltage Regulator
• Manufacturer: STMicroelectronics

ELECTRICAL CHARACTERISTICS (continued)
Note: 1. see fig4 (behavior of output current versus regulated voltage Vo)
2
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
The reset circuit monitors the output voltage Vo. If the output voltage drops below V
with a delay time trr. Real trr value changes as a non-linear function of delta (V
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:
ENABLE
V
V
V
Pin
R
E
E
E
E
cw
cw
cw
es
n
n
n
n
VOLTAGE REGULATOR
RESET
2. guaranteed by design
3. When Vo becomes lower than 4V, the reset reaction time decreases down to 2 s assuring a faster reset condition in this particular
case.
Symbol
V
V
I
V
T
I
I
_leak
t
en_hy
cwc
cwd
en_h
wop
wol
en_l
Charge current
Discharge current
Watchdog period
Watchdog output low time
Enable input low voltage
Enable input high voltage
Enable input hysteresis
Pull down current
Parameter
Vo_ref
Vo_ref
Vo
Vo
V
V
V
V
E
s
s
s
s
n
= 13.5V, V
= 13.5V, V
= 13.5V, C
= 13.5V, C
= 5V
Test Condition
Ishort Ilim
Ishort Ilim
cw
cw
tw
tw
= 47nF
= 47nF
= 0.1V
= 2.5V
Iout
Iout
o-th
Min.
700
1.0
25
4
6
3
2
- V
o_th
o
). The reset low signal is
1000
Typ.
then Res becomes low
7.5
2.4
50
10
10
L4979MD L4979D
Max.
1100
4.5
14
90
22
20
1
Unit
mV
ms
ms
V
V
A
A
A
5/10