©2011 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.3
Features
KA278RXXC-series (33/05/12 )
• 3.3V, 5V, 12V output low dropout voltage regulator
• TO-220 full-mold package (4pin)
• Overcurrent protection, thermal shutdown
• Overvoltage protection, short circuit protection
• With output disable function
KA278RA05C
• Nominal 5V output without adjusting
• Output adjustable between 1.25V and 32V
• 2A output low dropout voltage regulator
• TO-220 full-mold package (4pin)
• Overcurrent protection, thermal shutdown
• Overvoltage protection, short circuit protection
Description
The KA278RXXC is a low-dropout voltage regulator suit-
able for various electronic equipments. It provides
constant voltage power source with TO-220-4 lead full mold
package. The dropout voltage of KA278RXXC is below
0.5V in full rated current(2A). This regulator has various
functions such as a peak current protection, a thermal shut
down, an overvoltage protection .
TO-220F-4L
1.Vin 2. Vo 3. GND 4. Vdis - KA278RXXC(33/05/12)
1
1.Vin 2. Vo 3. GND 4. Vadj - KA278RA05C
Internal Block Diagram
THERMAL SHUTDOWN
BANDGAP RE FE RENC E
OVERVOLTAGE
PROTECTION
SOA PRO T EC T I ON
SHORTCIRCUIT
PROTECTION
1
4
3
2
Vin
Vadj
Vo
GND
Q1
Rin
Rref
+
-
THERMAL SHUTDOWN
BANDGAP REFERENCE
OVERVOLTAGE
PROTECTION
SOA PROTECTION
SHORTCIRCUIT
PROTECTION
1
4
3
2
Vin
Vdis
Vo
GND
HIGH / LO W OUTPUT
ON / OFF
Q1
R1
R2
-
+
-
+
1.4V
(KA278RA05C)
(KA278R33/05/12C)
KA278RXXC-Series
2A Output Low Dropout Voltage Regulators
KA278RXXC-SERIES
2
Absolute Maximum Ratings
KA278RXXC, KA278RA05C
Parameter Symbol Value Unit Remark
Input voltage Vin 35 V -
Disable voltage KA278RXXC 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 -
KA278RXXC-SERIES
3
Electrical Characteristics
(Vin=Note3, Io=1.0A, Ta=25°C , unless otherwise specified)
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 cylinder.
-. Thermal grease applied between PKG and heat sink fixture.
3. KA278R33C : Vin = 5V
KA278R05C : Vin = 7V
KA278R12C : Vin = 15V
4. KA278R33C : Vin =4 to 10V
KA278R05C : Vin=6 to 12V
KA278R12C : Vin = 13V to 29V
Parameter Symbol Conditions Min. Typ. Max. Unit
Output voltage KA278R33C Vo - 3.22 3.3 3.38 VKA278R05C - 4.88 5 5.12
KA278R12C - 11.7 12 12.3
Load regulation Rload 5mA < Io < 2A - 0.1 2.0 %
Line regulation Rline Note4 - 0.5 2.5 %
Ripple rejection ratio RR Note1 45 55 - dB
Dropout voltage Vdrop Io = 2A - - 0.5 V
Disable voltage high KA278RXXC VdisH Output active 2.0 - - V
Disable voltage low KA278RXXC VdisL Output disabled - - 0.8 V
Disable bias current high KA278RXXC IdisH Vdis = 2.7V - - 20 μA
Disable bias current low KA278RXXC IdisL Vdis = 0.4V - - -0.4 mA
Quiescent current Iq Io = 0A - - 10 mA
Reference voltage KA278RA05C Vref - 1.24 1.27 1.30 V
KA278RXXC-SERIES
4
Typical Performance Characteristics
KA278R33C
Input voltage Vin (V)
4.50
3.75
3.00
2.25
1.50
0.75
5.25
00 2 4 6 8 10
Output voltage Vo(V)
RL=
RL=3.3Ω
8
0 5 10 15 20
0
20
40
60
80
100
∞
RL=
Quiescent current Iq(mA)
Input voltage Vin(V)
0
Output voltage Vo(V)
3
Disable voltage Vdis (V)
0.5 1.5
122.5
4.50
3.75
3.00
2.25
1.50
0.75
5.25
0
3.34
3.32
3.30
3.36
-25
Output v oltage Vo(V)
TEMPERATURE Tj(oC)
75 125
02550 100
3.26
3.24
3.22
3.28
10
8
6
4
2
0
Quiescent current Iq(mA)
Junction temperature Tj(oC)
75 125
02550 100
-25 -25 0 25 50 75 100 125
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
2.0A
Drop out voltage Vdrop [V]
Jun c tion T e m p T j [℃]
Figure 1. Output Voltage vs. Input Voltage Figure 2. Quiescent Current vs. Input Voltage
Figure 4. Output Voltage vs. Temperature(Tj)
Figure 3. Output Voltage vs. Disable Voltage
Figure 5. Quiescent Current vs. Temperature(Tj) Figure 6. Dropout Voltage vs.Junction Temperature
KA278RXXC-SERIES
5
Typical Performance Characteristics (Continued)
-25
Power dissipation PD(W)
TEMPERATURE Tj(oC)
75 125
02550 100
15
10
5
20
0Output Current(A)
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
Output Current(A)
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
0123456
3.50
3.75
4.00
4.25
4.50
4.75
Output peak current Iop (A)
Input-output differential voltage Vin-Vo (V)
Figure 9. Output Peak Currenrt vs.
Input-Output Differential Voltage
Figure 7. Power Dissipation vs. Temperature(Tj) Figure 8. Overcurrent Protection Characteristics
(Typical Value)
KA278RXXC-SERIES
6
Typical Performance Characteristics(Continued)
KA278R05C
51015
Input voltage Vin (V)
6
5
4
3
2
1
7
00
Output volt age Vo( V)
RL=
RL=2.5Ω
8
0 5 10 15 20
0
20
40
60
80
100
120
∞
RL=
Quiescent current Iq(mA)
Input voltage Vin(V)
7
6
5
4
3
00
Output voltage Vo(V)
3
Disable voltage Vdis (V)
0.5 1.5
2
1
122.5
5.04
5.02
5.00
5.06
-25
Output voltage Vo(V)
TEMPERATURE Tj(oC)
75 125
02550 100
4.96
4.94
4.92
4.98
8
6
4
2
0
Quiescent current I q(mA)
Junction temperature Tj(oC)
75 125
02550 100
-25 -25 0 25 50 75 100 125
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
2.0A
Drop out voltage Vdrop [V]
Junction Temp Tj [℃]
Figure 1. Output Voltage vs. Input Voltage Figure 2. Quiescent Current vs. Input Voltage
Figure 4. Output Voltage vs. Temperature(Tj)
Figure 3. Output Voltage vs. Disable Voltage
Figure 5. Quiescent Current vs. Temperature(Tj) Figure 6. Dropout Voltage vs.Junction Temperature
KA278RXXC-SERIES
7
Typical Performance Characteristics (Continued)
-25
Power dissipation PD(W)
TEMPERATURE Tj(oC)
75 125
02550 100
15
10
5
20
0
Output Current(A)
Relative o utput voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
0
40
6.0
Output Current(A)
Relative o utput voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
0
40
6.0
0123456
3.50
3.75
4.00
4.25
4.50
4.75
Output peak current Iop (A)
Input-output differential voltage Vin-Vo (V)
Figure 7. Power Dissipation vs. Temperature(Tj) Figure 8. Overcurrent Protection Characteristics
(Typical Value)
Figure 9. Output Peak Currenrt vs.
Input-Output Differential Voltage
KA278RXXC-SERIES
8
Typical Performance Characteristics (Continued)
KA278R12C
51015
Input voltage Vin (V)
15.0
12.5
10.0
7.5
5.0
2.5
00
Output volt age Vo(V)
RL=
RL= 6Ω
20 25
8
0 5 10 15 20
0
20
40
60
80
100
120
∞
RL=
Quie sc e nt c u rre nt Iq (m A )
Input voltage Vin(V)
0
Output voltage Vo(V)
3
Disable voltage Vdis (V )
0.5 1.5
122.5
15.0
12.5
10.0
7.5
5.0
2.5
0
12.04
12.02
12.00
-25
Output voltage Vo(V)
TEMPERAT URE Tj(oC)
75 125
02550 100
11.96
11.94
11.92
11.98
10
8
6
4
2
0
Quiescent current Iq(mA)
Junction t e m p er at ur e T j(oC)
75 125
02550 100
-25 -25 0 25 50 75 100 125
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
2.0A
Drop out voltage Vdrop [V]
Junction T e mp Tj [℃]
Figure 1. Output Voltage vs. Input Voltage Figure 2. Quiescent Current vs. Input Voltage
Figure 4. Output Voltage vs. Temperature(Tj)
Figure 3. Output Voltage vs. Disable Voltage
Figure 5. Quiescent Current vs. Temperature(Tj) Figure 6. Dropout Voltage vs.Junction Temperature
KA278RXXC-SERIES
9
Typical Performance Characteristics (Continued)
-25
Power dissipation PD(W)
TEMPERATURE Tj(oC)
75 125
02550 100
15
10
5
20
0Output Current(A)
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
Output Current(A)
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
0123456
3.50
3.75
4.00
4.25
4.50
4.75
Output peak current Iop (A)
Input-output differential voltage Vin-Vo (V)
Figure 7. Power Dissipation vs. Temperature(Tj) Figure 8. Overcurrent Protection Characteristics
(Typical Value)
0123456
3.50
3.75
4.00
4.25
4.50
4.75
Output peak current Iop (A)
Input-output differential voltage Vin-Vo (V)
Figure 9. Output Peak Currenrt vs.
Input-Output Differential Voltage
KA278RXXC-SERIES
10
Typical Performance Characteristics (Continued)
KA278RA05C
51015
Input voltage Vin (V)
6
5
4
3
2
1
7
00
Output v oltage Vo(V)
RL=
RL=2.5Ω
8
0 5 10 15 20
0
20
40
60
80
100
120
∞
RL=
Quiescent current Iq(mA)
Input voltage Vin(V)
5.04
5.02
5.00
5.06
-25
Output voltage Vo(V)
TEMPERATURE Tj(oC)
75 125
02550 100
4.96
4.94
4.92
4.98
10
8
6
4
2
0
Quiescent current Iq(mA)
Junction temperature Tj(oC )
75 125
02550 100
-25
Figure 1. Output Voltage vs. Input Voltage Figure 2. Quiescent Current vs. Input Voltage
Figure 3. Output Voltage vs. Temperature(Tj)
Figure 6. Power Dissipation vs. Temperature(Tj)
Figure 5. Dropout Voltage vs.Junction Temperature
-25 0 25 50 75 100 125
0.30
0.35
0.40
0.45
0.50
0.55
0.60
0.65
0.70
2.0A
Drop out voltage Vdrop [V]
Junction Temp Tj [℃]
* Fixed Mode (Vo=5V) Figure 4. Quiescent Current vs. Temperature(Tj)
-25
Power dissipation PD(W)
TEMPERATURE Tj(oC)
75 125
02550 100
15
10
5
20
0
KA278RXXC-SERIES
11
Typical Performance Characteristics (Continued)
0123456
3.50
3.75
4.00
4.25
4.50
4.75
Output peak current Iop (A)
Input-o utput differe ntial voltag e Vin-V o (V)
Figure 7. Overcurrent Protection
Characteristics(Typical value) Figure 8. Output Peak Currenrt vs.
Input-Output Differential Voltage
Output Current(A)
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
Output Current(A)
Relative output voltage(%)
3.0 5.0
01.02.0 4.0
80
60
20
100
0
40
6.0
KA278RXXC-SERIES
12
Typical Application
KA278R33/05/12C
Figure 1. Application Circuit
• Ci is required if regulator is located at an appreciable distance from power supply filter.
• Co improves stability and transient response.(Co > 47μF)
KA278RA05
• Ci is required if regulator is located at an appreciable distance from power supply filter.
• Co improves stability and transient response.(CO > 47μF)
+
+
12
3
4
Vin
Vdis
Vo
GND
Disable Signal
KA278RA05
2
Vin
1
3
R3
GND 4
Vo
Vadj
R4
Co RL
Ci
Output
Input
Vo = 1.25 ( 1 + ) R1= 1.8kΩ, R2= 0.6kΩ
R1//R3
R2//R4
KA278RA05
2
Vin
1
3
R3
GND 4
Vo
Vadj
R4
Co RL
Ci
Output
Input
KA278RA05
2
Vin
1
3
R3
GND 4
Vo
Vadj
R4
Co RL
Ci
Output
Input
Vo = 1.25 ( 1 + ) R1= 1.8kΩ, R2= 0.6kΩ
R1//R3
R2//R4
Vo = 1.25 ( 1 + ) R1= 1.8kΩ, R2= 0.6kΩ
R1//R3
R2//R4
20
15
10
-50
Variation(%)
50 100 125
-25 0 25 75
0
-5
-10
5
Junction temperature Tj(℃)
25
20
15
10
-50
Variation(%)
50 100 125
-25 0 25 75
50 100 125
-25 0 25 75
0
-5
-10
5
Junction temperature Tj(℃)
25
KA278RA05
2
Vin
1
3
GND 4
Vo
Vadj Co RL
Ci
Output = 5V
Input
KA278RA05
2
Vin
1
3
GND 4
Vo
Vadj Co RL
Ci
Output = 5V
Input
Figure 2. Application Circuit (Adjustable Mode)
Figure 3. Internal Resistor(R1,R2) Variation vs. Temperature(Tj)
Figure 4. Application Circuit (Fixed Mode)
KA278RXXC-SERIES
13
Mechanical Dimensions
Package Dimensions in millimeters
TO-220F-4L
KA278RXXC-SERIES
14
Mechanical Dimensions (Continued)
Package Dimensions in millimeters
TO-220F-4L(Forming)
KA278RXXC-SERIES
9/29/11 0.0m 001
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© 2011 Fairchild Semiconductor Corporation
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FAIRCHILD’S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES
OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR
CORPORATION. As used herein:
1. Life support devices or systems are devices or systems
which, (a) are intended for surgical implant into the body,
or (b) support or sustain life, and (c) whose failure to
perform when properly used in accordance with
instructions for use provided in the labeling, can be
reasonably expected to result in a significant injury of the
user.
2. A critical component in any component of a life support
device or system whose failure to perform can be
reasonably expected to cause the failure of the life support
device or system, or to affect its safety or effectiveness.
www.fairchildsemi.com
DISCLAIMER
FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY
PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRC HILD DOES NOT ASSUME ANY
LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUC T OR CIRCUIT DESCRIBED HEREIN ; NEITHER
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Ordering Information
Product Number Package Operating Temperature
KA278R33CTU
TO-220F-4L -20°C to +80°C
KA278R05CTU
KA278R12CTU
KA278RA05CTU
KA278R12CYDTU TO-220F-4L(Forming)
