Fairchild Semiconductor KA278R05 Datasheet
KA278R05
Low Dropout Voltage Regulator
www.fairchildsemi.com
Features
• 2A/5V Output Low Dropout Voltage Regulator
• TO-220 Full-Mold Package (4Pin)
• Overcurrent Protection, Thermal Shutdown
• Overvoltage Protection, Short Circuit Protection
• With Output Disable Function
Internal Block Diagram
1
Vin
Description
The KA278R05 is a low-dropout voltage regulator suitable
for various electronic equipments. It provides constant
voltage power source with TO-220 4 lead full mold package.
The dropout voltage of KA278R05 is below 0.5V in full
rated current(2A). This re gulator has various f unctions such
as a peak current protection, a thermal shut down, an
overvoltage protection and an output disable function.
TO-220F-4L
1
1.Vin 2. Vo 3. GND 4. Vdis
Q1
2
Vo
THERMAL SHUTDOWN
BANDGAP REFERENCE
HIGH / LOW OUTPUT
4
Vdis
1.4V
©2002 Fairchild Semiconductor Corporation
+
ON / OFF
OVERVOLTAGE
PROTECTION
+
SOA PROTECTION
SHORT-CIRCUIT
SHORTCIRCUIT
PROTECTION
3
GND
R1
R2
Rev. 1.0.2
KA278R05
Absolute Maximum Ratings
Parameter Symbol Value Unit Remark
Input Voltage Vin 35 V Disable Voltage Vdis 35 V Output Current Io 2.0 A Power Dissipation 1 Pd1 1.5 W No Heatsink
Power Dissipation 2 Pd2 15 W With Heatsink
Junction Temperature Tj 150 °C-
Operating Temperature Topr -20 ~ 80 °C-
Thermal Resistance, Junction-to Case (Note2) Rθjc 2.9 °C/W -
Thermal Resistance, Junction-to-Air (Note2) Rθja 48.51 °C/W Thermal Shutdown Temperature Ttsd 150 °C-
Electrical Characteristics
(Vin=7V, Io=1.0A, Ta=25°C , unless otherwise specified)
Parameter Symbol Conditions Min. Typ. Max. Unit
Output Voltage Vo - 4.88 5 5.12 V
Load Regulation Rload 5mA < Io < 2A - 0.1 2.0 %
Line Regulation Rline 6V < Vin < 12V - 0.5 2.5 %
Ripple Rejection Ratio RR note1 45 55 - dB
Dropout Voltage Vdrop Io = 2A - - 0.5 V
Disable Voltage High VdisH Output Active 2.0 - - V
Disable Voltage Low VdisL Output Disabled - - 0.8 V
Disable Bias Current High IdisH Vdis = 2.7V - - 20 µA
Disable Bias Current Low IdisL Vdis = 0.4V - - -0.4 mA
Quiescent Current Iq Io = 0A - - 10 mA
Note:
1.These parameters, although guaranteed, are not 100% tested in production.
2. Junction -to -case thermal resistance test environments.
-. Pneumatic heat sink fixture.
-. Clamping pressure 60psi through 12mm diameter cyl ind er.
-. Thermal gr ease applied be tween PKG and h eat sink fixtur e
2
Typi ca l Performance Characteristics
KA278R05
7
6
5
4
3
2
Output voltage Vo(V)
1
0
0
8
RL=
Ω
RL=2.5
51015
Input voltage Vin (V)
Figure 1. Output Voltage vs. Input Voltage
7
6
5
4
3
2
Output voltage Vo(V)
1
50
40
30
20
10
Quiescent current Iq(mA)
0
0
RL=
5
10
15
Input voltage Vin (V)
Figure 2. Quiescent Current vs. Input Voltage
5.06
5.04
5.02
5.00
4.98
4.96
Output voltage Vo(V)
4.94
0
0
0.5
122.5
1.5
3
Disable voltage Vdis (V)
Figure 3. Output Voltage vs. Disable Voltage
8
6
4
2
Quiescent current Iq(mA)
0
02550
-25
75
100
125
Junction temperature Tj(oC)
Figure 5. Quiescent Current vs. Temperature(Tj)
4.92
-25
02550
Temperature Tj(°C)
TEMPERATURE Tj(oC)
75
100
125
Figure 4. Output Voltage vs. Temperature(Tj)
0.6
0.5
0.4
0.3
0.2
Dropout voltage Vdrop(V)
0.1
0
02550
-25
Io=2A
1.5A
1.0A
0.5A
75
100
125
Junction temperature Tj(oC)
Figure 6. Dropout Voltage vs. Junction Temperature
3
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