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PDF L4954 Data sheet ( Hoja de datos )

Número de pieza L4954
Descripción QUAD MULTIFUNCTION VOLTAGE REGULATOR FOR CAR RADIO
Fabricantes STMicroelectronics 
Logotipo STMicroelectronics Logotipo



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® L4954
QUAD MULTIFUNCTION
VOLTAGE REGULATOR FOR CAR RADIO
4 REGULATORS
10V (40mA); 8.5V (175mA); 5V (650mA);
5V (100mA) STANDBY
10V AND 5V STAND BY REGULATORS ARE
LOW DROPOUT OUTPUTS
3 HIGH SIDE DRIVERS:
2A (HSD1), 0.3A (HSD2 & HSD3)
NO EXTERNAL CHARGE PUMP CAPACI-
TORS ARE REQUIRED
STAND BY MODE CONTROLLED BY 3 IN-
PUT PINS:
EN1 FOR REG1, REG2, REG3 AND HSD1,
EN2 FOR HSD2, AND EN3 FOR HSD3
INDIVIDUAL THERMAL SHUTDOWN
LOGIC OUTPUTS FOR SUPPLY UNDER-
VOLTAGE: (LVWARN, RESET)
INDEPENDENT CURRENT LIMITING
OVERVOLTAGE SHUTDOWN
SHORT CIRCUIT PROTECTION
LOAD DUMP PROTECTION AND OVERVOL-
TAGE SHUTDOWN
DESCRIPTION
L4954 is a quad output voltage regulator and a
BLOCK DIAGRAM
Multiwatt15
ORDERING NUMBER: L4954
three output high side driver.
The IC includes monitoring circuitry to warn the
microprocessor of a low voltage condition:
the LVWarn, output, sensing the slow dropping of
STCAP pins voltage, gives the microprocessor
time to store data.
A RESET output is generatedat REG4’s decay.
External protection must be provided for reverse
battery protection.
June 2000
VS
STCAP
RESET
LVWarn
EN1
EN2
EN3
GND
VOLTAGE
REFERENCE
CURRENT
LIMIT
RESET
LVW
OUTPUT
CONTROL
THERMAL
SHUTDOWN
OVERVOLTAGE
PROTECTION
REG1
10V, 40mA
REG2
8.5V, 175mA
REG3
5V, 650mA
REG4
5V, 100mA
HSD1
2.0A
HSD2
0.3A
HSD3
0.3A
10V-REG1
8.5V-REG2
5V-REG3
5V-REG4-STBY
HSD1
HSD2
HSD3
D95AU346
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L4954 pdf
L4954
ELECTRICAL CHARACTERISTICS (Continued)
Symbol
Parameter
LVWARN OUTPUT
THLVW LVW Threshold on STCAP
VLVW
LVW Output Voltage
trise LVW Output Rise Time
tfall LVW Output Fall Time
RESET OUTPUT
T HRES
VRES
Reset Threshold on Reg 4
Reset Output Voltage
trise Reset Output Rise Time
tfall Reset Output Fall Time
Test Condition
Min. Typ. Max. Unit
STCAP <7.5V; VIL = ”0”
STCAP >7.5V VIH = ”1”
CLVW = 0.1µF
CLVW = 0.1µF
0
2.75
7.5
3.9
12.6
0.4
5
V
V
V
ms
µs
4.5 V
Set VS so that VOUT5STBY <4.5V;
VIL = ”0”
Set VS so that VOUT5STBY is not
less than normal REG4 output
voltage; VIH = ”1”
0
2.75
0.4 V
5V
CRESET = 0.1µF
CRESET = 0.1µF
4.5 ms
37 µs
FUNCTIONAL DESCRIPTION
The L4954 includes a monitoring circuit to warn
the microprocessor if a low voltage or no voltage
condition is occurring.
When the voltage on the STCAP pin drops below
7.5V (typ), the LVW output will go low. This tells
the microprocessor to stop executing code and
save vital information. The reset output will go low
when REG4 (5V-STBY) drops below (VREG4 -
250mV) or 4.75V is minimum value. The RESET
output doesn’t go above 0.4V until REG4 has
gone back above 4.75V (min).
Any spike will tell the microprocessor to start op-
erating. Once the STCAP line passes 7.5V (typ),
the LVWarn output will also return to high state.
The STCAP pin acts like a delay circuit. Due to
the large capacitor (470µF), the STCAP pin al-
lows the battery voltage to decay slowly giving the
microprocessor time to store data.
Also, during short low voltage or negative voltage
conditions, the STCAP pin protects the 5V STBY
output from dropping below the RESET and LVW
trip points. The four outputs are expected to fol-
low the battery voltage down to 11V for REG1,
9V for REG2, 6V for REG3 and REG4.
The L4954 has a STBY mode to keep the micro-
processor and memories alive during an ignition
off conditions. The EN1 input pin is controlled by
the microprocessor. A high on the EN1 input turns
on REG1, REG2, REG3, and HSD1. A Low on
EN1 places the part in stand-by mode with REG4
on. The High side driver outputs HSD2 and HSD3
are controlled by EN2 and EN3 respectively: a
Low on the control input turns the corresponding
high side driver off.
TIMING DIAGRAM
STCAP
(V)
0
5
REG4
(V)
0
5
LVWarn
(V)
5
RESET
(V)
0.4
7.5 7.5
4.75 4.75
TIME
TIME
TIME
D95AU349A
TIME
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