L4947 View Datasheet(PDF) - STMicroelectronics
Part Name
Description
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L4947 Datasheet PDF : 6 Pages
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L4947 - L4947R
ELECTRICAL CHARACTERISTICS (refer to the test circuit, Vi = 14. 4V, Co = 47µF, ESR < 10Ω,
Rp = 1KΩ, RL = 1KΩ, –40°C ≤ TJ ≤ 125°C, unless otherwise specified)
Symbol
Vo
Parameter
Output Voltage
Vi
∆Vo
∆Vo
Vi –Vo
Iq
Operating Input Voltage
Line Regulation
Load Regulation
Dropout Voltage
Quiescent Current
∆Vo
T
SVR
Temperature Output Voltage
Drift
Supply Volt. Rej.
Isc
Output Short Circuit Current
Test Conditions
Io = 0mA to 500mA
Over Full T Range
TJ = 25°C
Io = 0mA to (*) 500mA
Vi = 6V to 26V ;
Io = 5mA
Io = 5mA to 500mA
Io = 500mA, TJ = 25°C
Over Full T Range
Io = 0mA, TJ = 25°C
Io = 0mA Over Full T
Io = 500mA Over Full T
Io = 350mA ; f = 120Hz
Co = 100µF ;
Vi = 12V ± 5Vpp
VR
IR
VRT peak
VRT (off)
VRT (on)
VHyst
Vd
VdH
Id
Vdisch
Td
Reset Output Saturation Voltage
Reset Output Leakage Current
Power On-Off Reset out Peak
Voltage
Power OFF Vo Threshold
Power ON Vo Threshold
Power ON-Off Hysteresis
Delay Comparator Threshold
Delay Comparator Hysteresis
Delay Capacitor Charging
Current
Delay Capacitor Discharge
Voltage
Power on Reset Delay Time
1.5V < Vo < VRT (off),
IR = 1.6mA
3.0V < Vo < VRT (off),
IR = 8mA
VO in Regulation, VR = 5V
1KΩ Reset Pull-up to Vo, TJ =
25°C
TJ = 25°C
L4947: Vo @ Reset Out H to L
Transition
L4947R: Vo @ Reset Out H to
L Transition
Vo @ Reset Out L to H
Transition
VRT (on) –VRT (off)
Vd @ Reset Out L to H
Transition
Vd @ Reset Out H to L
Transition
Vd = 3V, TJ = 25°C
Vo < VRT (off)
Cd = 100nF, TJ = 25°C
(*) For a DC voltage 26 < Vi < 37V the device is not operating
Min.
4.80
4.90
6
50
Typ.
5.00
5.00
2
15
0.40
5
6.5
110
– 0.5
60
Max. Unit
5.20
V
5.10
V
26
V
10
mV
60
mV
0.55
V
0.75
V
10
mA
13
mA
180 mA
mV/°C
dB
0.50 0.80 1.50
A
0.40
V
0.40
V
50
µA
0.50 0.80
V
4.70
V
4.75 Vo–0.15
V
4.55 Vo–0.30
V
VRT (off) Vo –
V
+ 0.05 0.04
0.05
V
3.65 4.00 4.35
V
3.20 3.55 3.90
V
0.45
V
20
/µA
0.55 1.20
V
10
20
30
ms
FUNCTIONAL DESCRIPTION
The L4947/L4947R is a very low drop 5V/0.5A
voltage regulator provided with a reset function
and therefore particularly suited to meet the re-
quirements of supplying the microprocessor sys-
tems used in automotive and industrial applica-
tions.
The block diagram shows the basic structure of
the device : the reference, the error amplifier, the
driver, the power PNP, the protection and reset
functions.
The power stage is a Lateral PNP transistor
which allows a very low dropout voltage (typ.
400mV at TJ = 25°C, max. 750mV over the full
temperature range @ IO = 500mA). The typical
curve of the dropout voltage as a function of the
junction temperature is shown in Fig. 1 : that is
the worst case, where IO = 500mA.
3/6
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