ME78L05
3-Terminal
General Description
ME78L05 is three-terminal positive regulators.
One of these regulators can deliver up to 100 mA of
output current. The internal limiting and thermal
-shutdown features of the regulator make them
essentially immune to overload. When used as a
replacement for a zener diode-resistor Comb-
ination, an effective improvement in output impe-
dance can be obtained, together with lower
quiescent current.
Positive Voltage Regulator ME78L05
Features
●Output
Current of 100mA
●Output
Voltages of 5V±5% over the temp-
erature range
●Thermal
Overload Protection
●Short
Circuit Protection
●Output
transistor safe area protection
●No
external components
●Package：SOT89-3
Pin Configuration
1. Output
2. GND
3. Input
Maximum Ratings(Ta=25℃)
Parameter
Input supply voltage : VIN
MAX. Output current:Iout
Max Power:Pmax
Maximum junction temperature: T
j
Storage temperature :T
str
Soldering temperature and time
Rating
30
100
0.35
-25½125
-55½150
+260（Recommended 10S）
Unit
V
mA
W
℃
℃
℃
Caution: The absolute maximum ratings are rated values exceeding which the product could suffer physical damage.
These values must therefore not be exceeded under any conditions.
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ME78L05
Block Diagram
Electrical Characteristics
(Cin =0.33μF, Co =0.1μF,0≤Tj≤125
O
C, unless otherwise noted)
Parameter
Symbol
Conditions
I
O
=40mA, VIN=10V
Output Voltage
V
O
I
O
=1mA½40mA
VIN=7V½20V
I
O
=1mA½10mA
VIN=10V
Line Regulations
Load Regulation
Dropout Voltage
Output noise Voltage
Ripple Rejection
Quiescent Current
Quiescent Current
Change
LNR
LDR
V
DIF
V
N
PSRR
I
Q
ΔI
Q
VIN=7V½20V,I
O
=40mA
VIN=8V½20V,I
O
=40mA
VIN=10V,I
O
=1mA-100mA
VIN=10V,I
O
=1mA-40mA
Tj=25
O
C,Io=100mA
f=10Hz to 100KHz
Tj=25
O
C,f=120Hz,Io=40mA
VIN=8V½20V
VIN=10V,I
OUT
=40mA
VIN=8V½20V,I
O
=40mA
VIN=10V,I
O
=1mA½40mA,
Min.
4.82
4.8
4.75
-150
-100
-60
-30
-
-
-
-
-1.5
-0.1
Typ.
5.0
5.0
5.0
-
-
-
-
2
40
80
-
-
-
Max.
5.18
5.2
5.25
150
100
60
30
-
-
-
5.5
1.5
0.1
mV
mV
V
μV/Vo
dB
mA
mA
V
Unit
LNR: Line Regulation. The change in output voltage for a change in the input voltage. The measurement is made
under conditions of low dissipation or by using pulse techniques such that the average chip temperature is
not significantly affected.
LDR: Load Regulation.The change in output voltage for a change in load current at constant chip temperature.
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ME78L05
T
ype Characteristics
Ta=25℃
Io=100mA
VIN=10V
Ta=25℃
Io=40mA
Io=10mA
VIN=7V
VIN=10V
Ta=25℃
Io=40mA
Ta=25℃
VIN=10V
Ta=25℃
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ME78L05
Operation Description
ME78L05 is designed with Thermal Overload Protection that shuts down the circuit when subjected to an
excessive power overload condition, Internal Short Circuit Protection that limits the maximum current the circuit will
pass, and Output Transistor Safe-Area Compensation that reduces the output short circuit current as the voltage
across the pass transistor is increased.
In many low current applications, compensation capacitors are not required. However, it is recommended that
the regulator input be bypassed with a capacitor if the regulator is connected to the power supply filter with long wire
lengths, or if the output load capacitance is large. An input bypass capacitor should be selected to provide good high
frequency characteristics to insure stable operation under all load conditions. A 0.33μFor larger tantalum, mylar, or
other capacitor having low internal impedance at high frequencies should be chosen. The bypass capacitor should
be mounted with the shortest possible leads directly across the regulator’s input terminals. Normally good
construction techniques should be used to minimize ground loops and lead resistance drops since the regulator has
no external sense lead.
Typical Application Circuit
Fig.1 Fixed Output Regulator
A common ground is required between the input and the output voltages. The input voltage must remain typically
2.0 V above the output voltage even during the low point on the input ripple voltage.
●Cin
is required if regulator is located an appreciable distance from power supply filter.
●Co
is not needed for stability; however, it does improve transient response.
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ME78L05
ME78L05
VIN
Cin
0.33
μF
Input
Output
GND
R
I
Q
Fig.2 Constant Current Regulator
Io
Constant Current to
Grounded Load
The ME78L05 regulatorcan also be used as a current source when connected as Fig.2. In order to minimize
dissipation the ME78L05 is chosen in this application. Resistor R determines the current as follows:
I
O
=
5V
+I
Q
R
ME78L05
VIN
Cin
0.33
μF
Input
Output
GND
R1
Vo
R2
0.1
μF
Fig.3 Adjustable Output Regulator
Vo=5V+(5V/R1+I
Q
)*R2
5V/R1>3*I
Q
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