2003 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.0
Features
KA278RXXC-series (33/05/51/09/12)
2A/3.3V, 5V, 5.1V, 9V, 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(33/05/51/09/12)
1
1.Vin 2. Vo 3. GND 4. Vadj - KA278RA05C
Internal Block Diagram
THERMAL SHUTDOWN
BANDGAP REFERENCE
OVERVOLTAGE
PROTECTION
SOA PROTECTION
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 / LOW
OUTPUT
ON / OFF
Q1
R1
R2
-
+
-
+
1.4V
(KA278RA05C)
(KA278R33/05/51/09/12C)
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)
R
jc
2.9
C/W
-
Thermal resistance, junction-to-air (note2)
R
ja
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
KA278R09C : Vin = 11V
KA278R12C : Vin = 15V
4. KA278R33C : Vin =4 to 10V
KA278R05C, KA278R51C : Vin=6 to 12V
KA278R09C : Vin=10 to 25V
KA278R12C : Vin = 13V to 29V
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
Output voltage
KA278R33C
Vo
-
3.22
3.3
3.38
V
KA278R05C
-
4.88
5
5.12
KA278R51C
-
4.98
5.1
5.22
KA278R09C
-
8.78
9
9.22
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
A
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
0
0 2 4 6 8 10
O
u
t
put voltage V
o
(V
)
RL=
RL=3.3
8
0
5
10
15
20
0
20
40
60
80
100
RL=
Q
u
iesc
ent
cur
r
en
t
I
q
(
m
A
)
Input voltage Vin(V)
0
O
u
t
put
vo
l
t
a
ge
V
o
(
V
)
3
Disable voltage Vdis (V)
0.5
1.5
1
2
2.5
4.50
3.75
3.00
2.25
1.50
0.75
5.25
0
3.34
3.32
3.30
3.36
-25
O
u
tput
volta
ge
V
o
(V
)
TEMPERATURE Tj(
o
C)
75
125
0
25
50
100
3.26
3.24
3.22
3.28
10
8
6
4
2
0
Quiescent cur
r
e
n
t
I
q
(
m
A
)
Junction temperature Tj(
o
C)
75
125
0
25
50
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
D
r
op
out
v
o
l
t
age
V
d
r
o
p [
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
5
Typical Performance Characteristics
(Continued)
-25
P
o
w
e
r di
s
sipat
i
on P
D
(W)
TEMPERATURE Tj(
o
C)
75
125
0
25
50
100
15
10
5
20
0
Output Current(A)
R
e
l
a
t
i
v
e
o
u
t
put
v
o
l
t
a
ge(
%)
3.0
5.0
0
1.0
2.0
4.0
80
60
20
100
0
40
6.0
Output Current(A)
R
e
l
a
t
i
v
e
o
u
t
put
v
o
l
t
a
ge(
%)
3.0
5.0
0
1.0
2.0
4.0
80
60
20
100
0
40
6.0
R
e
l
a
t
i
v
e
o
u
t
put
v
o
l
t
a
ge(
%)
3.0
5.0
0
1.0
2.0
4.0
80
60
20
100
0
40
6.0
0
1
2
3
4
5
6
3.50
3.75
4.00
4.25
4.50
4.75
O
u
t
p
ut
p
eak
c
u
r
r
en
t
I
op
(
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)
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