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PDF L9777 Data sheet ( Hoja de datos )
| Número de pieza | L9777 | |
| Descripción | Low power voltage regulator | |
| Fabricantes | STMicroelectronics | |
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L9777
Low power voltage regulator
Features
■ Operating DC supply voltage range 5.6 V to
31 V
■ Low current consumption (110 µA typ @ Iout = 0)
■ High precision output voltage (2 %)
■ Low dropout voltage
■ VDD tracking regulator switchable on/off by
VDD_EN pin
■ Reset circuit sensing the output voltage down
to 1 V.
■ Double reset function
■ Adjustable reset threshold
■ External capacitor to set NMI/ reset power up
delay and watchdog frequency
■ Over temperature protection
■ Wide temperature range (TJ = -40 °C to 150 °C)
■ Short circuit proof
■ Suitable for use in automotive electronics
PowerSSO-12 (exposed DIE Pad)
Description
The L9777 is a monolithic integrated low drop
regulator which can supply up to 200 mA,
available in the PowerSSO-12 package.
It is designed to supply microprocessor systems
under severe conditions of automotive
applications and therefore equipped with
additional protection functions against over load,
short circuit and over temperature.
Of course the L9777 can also be used in other
applications where a regulated voltage is
required.
Table 1.
Device summary
Order code
L9777A
L9777B
L9777B13TR
L9777C
Package
PowerSSO-12
PowerSSO-12
PowerSSO-12
PowerSSO-12
Packing
Tray
Tray
Tape and reel
Tray
December 2010
Doc ID 13496 Rev 2
1/25
www.st.com
1
http://www.Datasheet4U.com
1 page  
L9777
1
Block diagrams and pins configuration
Block diagrams and pins configuration
1.1
Block diagram (option A)
Figure 1. Block diagram (option A)
Vbatt
VI
GND
WD_EN
Start up
VCC
Voltage
Reference
IWD_EN
WD
D
VD
CD
watchdog
RWD
VDD_EN
3R
R
1.26V
VOFF +_
10
IVDD=100mA
IVDD_EN
VDD
CVDD
VCC
IVCC=200mA
VMUXTH
CVCC
RRESET
RNMI
Delay
RADJ
TIMING
CTIMING
RESET
Low
Voltage
Reset
NMI
1.2
Option B features
● VDD can sustain short to 40 V regardless of VI battery voltage
● Current capability of VDD scaled down to 50 mA with dropout of 1.5 V (Max.)
● In default condition, VDD and WD functions are disabled using 2 pull down current on
VDD_EN and WD_EN pin
● Standby current consumption reduced to 100 µA (Typ.)
Figure 2. Package pin configuration (options A and B)
RESET
NMI
D
VDD_EN
WD
WD_EN
1 12
2 11
3 10
49
58
67
PinConfA_B
RADJ
GND
VDD
VCC
TIMING
VI
Doc ID 13496 Rev 2
5/25
5 Page 
L9777
3 Functional
description
Functional description
3.1 V
oltage regulator
This device supply an always active 5 V regulated voltage on pin VCC with a current
capability up to 200 mA. VCC voltage has an accuracy of 2% over a wide supply voltage (VI
= 5.6 V to 31 V) and temperature range (TJ = -40 °C to 150 °C).
A short circuit protection to GND is provided (see Figure 6).
By means of tracking regulator, it is available a second output regulated voltage on pin VDD
with a current capability up to 50mA. This regulated output is switchable on/off by external
pin VDD_EN.
Figure 6.
VCC versus output current IVCC
VCC
VCCREF
ISHORT ILIM
IVCC
3.2 Reset
The reset circuit monitors the output voltage VCC. In case of internal reset threshold, if the
output voltage stays lower than VCCUN for a filter time TRR, then NMI goes low.
This filter time depends on the distance between the VCC output and the under voltage
reset threshold (VCCUN): this solution increases the noise immunity of the voltage regulator
be-cause the filter time between the reset event and the falling of NMI output changes
according to the depth of spike on output voltage (see following picture).
A minimum filter time of 1 µs (TRR1) is guaranteed if VCC goes down to 2.5 V and VS >
5.6 V.
Figure 7. Filter time between VCC and NMI
VCC
NMI
VCC
V1
VCCUN
2.5V
NMI
TRR1
TRR2
Otherwise, in case of external reset threshold fixed by means of external resistor divider on
pin RADJ, there is only a constant filter time (TRRADJ) of 1 µs min value.
Doc ID 13496 Rev 2
11/25
11 Page | ||
| Páginas | Total 25 Páginas | |
| PDF Descargar | [ Datasheet L9777.PDF ] | |
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