MC78M15CDT ON Semiconductor, MC78M15CDT Datasheet - Page 9

• Manufacturer Part Number: MC78M15CDT
• Description: IC REG LDO 500MA 15V DPAK-3
• Manufacturer: ON Semiconductor

Specifications of MC78M15CDT

• Regulator Topology: Positive Fixed
• Voltage - Output: 15V
• Voltage - Input: Up to 35V
• Voltage - Dropout (typical): 2V @ 350mA
• Number Of Regulators: 1
• Current - Output: 500mA
• Operating Temperature: 0°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: TO-252-2, DPak (2 Leads + Tab), TO-252AA, SC-63
• Polarity: Positive
• Number Of Outputs: 1
• Output Type: Fixed
• Output Voltage: 15 V
• Output Current: 0.7 A
• Line Regulation: 50 mV
• Load Regulation: 300 mV
• Input Voltage Max: 35 V
• Maximum Operating Temperature: + 125 C
• Minimum Operating Temperature: 0 C
• Mounting Style: SMD/SMT
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Current - Limit (min): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

Design Considerations
regulators are 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.
capacitors are not required. However, it is recommended
that the regulator input be bypassed with a capacitor if the
The MC78M00/MC78M00A Series of fixed voltage
In many low current applications, compensation
Input
The MC78M00 series can be current boosted with a PNP
transistor. The MJ2955 provides current to 5.0 A. Resistor R in
conjunction with the V
transistor begins conducting; this circuit is not short circuit
proof. Input-output differential voltage minimum is increased
by V
0.33 mF
Input
The MC78M00 regulators can also be used as a current source
when connected as above. In order to minimize dissipation the
MC78M05C is chosen in this application. Resistor R determines
the current as follows:
For example, a 500 mA current source would require R to be a
10 W, 10 W resistor and the output voltage compliance would be
the input voltage less 7.0 V.
Figure 12. Current Boost Regulator
BE
of the pass transistor.
MJ2955 or Equiv.
R
Figure 10. Current Regulator
1.0 mF
XX = 2 digits of type number indicating voltage.
I
IB
= 1.5 mA over line and load changes.
BE
MC78M05C
I
of the PNP determines when the pass
O
=
MC78MXXC
5.0 V
R
+ I
IB
I
O
R
APPLICATIONS INFORMATION
Current to
Grounded
Constant
1.0 mF
Load
Output
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9
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 0.33 mF or 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.
Input
The addition of an operational amplifier allows adjustment to higher
or intermediate values while retaining regulation characteristics.
The minimum voltage obtainable with this arrangement is 2.0 V
greater than the regulator voltage.
Input
The circuit of Figure 12 can be modified to provide supply protection
against short circuits by adding a short circuit sense resistor, R
and an additional PNP transistor. The current sensing PNP must be
able to handle the short circuit current of the three-terminal
regulator .Therefore, a 4.0 A plastic power transistor is specified.
Figure 11. Adjustable Output Regulator
0.33 mF
R
XX = 2 digits of type number indicating voltage.
Figure 13. Current Boost with
1.0 k
MC78M05C
Short Circuit Protection
2N6049
or Equiv.
R
SC
6
MJ2955
or Equiv.
1.0 mF
4
7
MC1741
*
+
MC78MXXC
2
3
V
V
O
in
, 7.0 V to 20 V
-V
out
10 k
≥ 2.0 V
Output
Output
sc
,
0.1 mF