Fairchild Semiconductor KA278RA05 Datasheet
KA278RA05
Low Dropout Voltage Regulator
(Fixed & Adjustable)
www.fairchildsemi.com
Features
• Nominal 5V output without adjusting
• Output Adjustable Between 1.25V and 32V
• 2A Output low dropout vol t age regulator
• TO220 Full-Mold package (4PIN)
• Overcurrent protection, Thermal shutdown
• Overvoltage protection, Short-Circ uit protection
Internal Block Diagram
Description
The KA278RA05 is a low-dropout voltage regulator suitable
for various electronic equipments. It provides constant
voltage power source with TO-220F-4 lead full mold
package. Dropout voltage of KA278RA05 is below 0.5V in
full rated current(2A). This regulator has various function
such as peak current protection, thermal shut down and over
voltage prot ection.
TO-220F-4L
1
1. Vin 2. V
3. GND 4. Vadj
O
Vin
1
THERMAL SHUTDOWN
BANDGAP REFERENCE
©2001 Fairchild Semiconductor Corporation
OVERVOLTAGE
PROTECTION
-
+
SOA PROTECTION
SHORT-CIRCUIT
SHORTCIRCUIT
PROTECTION
3
GND
Q1
Rin
R1
R2
Rref
1.8kΩ
0.6kΩ
2
Vo
4
Vadj
Rev. 1.0.2
KA278RA05
Absolute Maximum Ratings
Parameter Symbol Value Unit Remark
Input Voltage Vin 35 V Output Current I
O
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-
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 < I
Line Regulation Rline 6V < Vin < 12V - 0.5 2.5 %
Ripple Rejection Ratio RR note1 45 55 - dB
Dropout Voltage Vdrop I
Quiescent Current Iq I
= 2A - - 0.5 V
O
= 0A - - 10 mA
O
Reference Voltage Vref - 1.24 1.27 1.30 V
< 2A - 0.1 2.0 %
O
Note:
1. These parameters, although guaranteed, are not 100% tested in production.
2
Typical Perfomance Characteristics
KA278RA05
7
6
5
4
3
2
Output voltage Vo(V)
1
0
0
RL=
8
ΩΩΩΩ
RL=2.5
51015
Input voltage Vin (V)
Figure 1. Output Voltage vs. Input Voltage
5.06
5.04
5.02
5.00
4.98
4.96
Output voltage Vo(V)
4.94
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
10
8
6
4
2
Quiescent current Iq(mA)
4.92
-25
02550
TEMPERATURE Tj(oC)
75
100
125
Figure 3. Output Voltage vs. Temperature(Tj)
*Fixed Mode (VO=5V)
0.6
0.5
0.4
0.3
0.2
Dropout voltage Vdrop(V)
0.1
0
02550
-25
Junction temperature Tj(oC)
Figure 5. Dropout Voltage vs. Junction Temperature
Io=2A
1.5A
1.0A
0.5A
75
100
125
0
02550
-25
75
100
125
Junction temperature Tj(oC )
Figure 4. Quiescent Current vs. Temperature(Tj)
20
(W)
D
15
D
10
5
Power dissipation P
0
02550
-25
TEMPERATUR E Tj(oC)
75
a
100
125
Figure 6. Power Dissipation vs. Temper ature(Ta)
3
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