2005 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.3
Features
3A/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
Description
The KA378R12 is a low-dropout voltage regulator suitable
for various electronic equipments. It provide constant
voltage power source with TO-220 4 lead full mold package.
Dropout voltage of KA378R12 is below 0.5V in full rated
current(3A). This regulator has various function such as
peak current protection, thermal shut down, overvoltage
protection and output disable function.
TO-220F-4L
1. Vin 2. Vo 3. GND 4. Vdis
1
Internal Block Diagram
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
SHORT-CIRCUIT
KA378R12
Low Dropout Voltage Regulator
KA378R12
2
Absolute Maximum Ratings
Electrical Characteristics
(Vin = 15V, Io = 1.5A, 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
Parameter
Symbol
Value
Unit
Remark
Input Voltage
Vin
35
V
-
Disable Voltage
Vdis
35
V
-
Output Current
Io
3.0
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 Shutdown Temperature
Ttsd
150
C
-
Storage Temperature
T
stg
-65 ~ 150
C
-
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
Output Voltage
Vo
-
11.7
12.0
12.3
V
Load Regulation
Rload
5mA < Io < 3A
-
0.1
2.0
%
Line Regulation
Rline
13V < Vin < 29V
-
0.5
2.5
%
Ripple Rejection Ratio
RR
Note1
45
55
-
dB
Dropout Voltage
Vdrop
Io = 3A
-
-
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
A
Disable Bias Current Low
IdisL
Vdis = 0.4V
-
-
-0.4
mA
Quiescent Current
Iq
Io = 0A
-
-
10
mA
KA378R12
3
Typical Performance Characteristics
Figure 1. Output Voltage vs. Input Voltage
Figure 3. Output Voltage vs. Disable Voltage
Figure 5. Quiescent Current vs. Temperature(Tj)
Figure 2. Quiescent Current vs. Input Voltage
Figure 4. Output Voltage vs. Temperature(Tj)
Figure 6. Dropout Voltage vs. Junction Temperature
17.5
O
u
t
put
vol
t
age V
o
(
V
)
25
Input voltage Vin (V)
5
10
15
15.0
12.5
10.0
7.5
5.0
2.5
0
0
RL=
RL=4
20
8
Disable voltage Vdis (V)
0
O
u
t
put
vol
t
age V
o
(
V
)
3
0.5
1.5
1
2
2.5
15.0
12.5
10.0
7.5
5.0
2.5
17.5
0
Junction temperature Tj(
o
C)
10
8
6
4
2
0
Q
u
i
e
s
c
e
n
t
c
u
rre
n
t
I
q
(m
A
)
75
125
0
25
50
100
-25
100
80
60
40
20
0
0
Q
u
i
e
sce
nt
cur
r
en
t
I
q
(
m
A
)
5
10
15
20
25
Input voltage Vin (V)
RL=
8
Temperature Tj(
o
C)
12.04
12.02
12.00
12.06
-25
O
u
t
put
vol
t
age V
o
(
V
)
75
125
0
25
50
100
11.96
11.94
11.92
11.98
Junction temperature Tj(
o
C)
125
0.6
0.5
0.4
0.3
0
D
r
o
p
o
u
t
vo
l
t
ag
e
V
d
r
o
p(
V
)
0.2
0.1
75
0
25
50
100
-25
Io=3A
2.0A
1.0A
0.5A
KA378R12
4
Typical Performance Characteristics
(Continued)
Figure 7. Power Dissipation vs. Temperature(Ta)
Figure 9. Ripple Rejection vs. Input Ripple Frequency
Figure 11. Load Transient Response
Figure 8. Overcurrent Protection Characteristics
(Typical value)
Figure 10. Line Transient Response
Temperature T
a
(
o
C)
-25
P
o
w
e
r
d
i
s
s
i
pa
t
i
on
P
D
(W
)
75
125
0
25
50
100
15
10
5
20
0
Input Ripple Frequency (KHz)
R
i
p
p
l
e
Re
j
e
c
t
i
o
n
RR (
d
B
)
50
40
30
20
10
0
0.1
100
1
10
60
70
T
j
= 25
o
C
V
IN
= 14V
I
O
= 1.5A
V
IN
= 0.5V
rms
Time (
s)
2.0
1.5
1.0
0.5
0
0
O
u
t
p
u
t
C
u
rre
n
t
(
A
)
10
20
2.5
3.0
0.0
-0.5
-1.0
-1.5
-2.0
-2.5
3.0
30
40
O
u
t
p
u
t
V
o
l
t
ag
e
D
e
v
i
at
i
o
n (
V
)
Output Current(A)
R
e
l
a
t
i
ve
out
put
vol
t
age(
%
)
3.0
5.0
0
1.0
2.0
4.0
80
60
20
100
0
40
6.0
7.0
Time (
s)
30
15
13
0
I
n
pu
t
V
o
l
t
a
ge
(
V
)
5
15
45
0
-15
-30
14
25
35
O
u
t
p
u
t
V
o
l
t
ag
e
D
e
v
i
at
i
o
n (
m
V
)
45
KA378R12
5
Typical Application
Figure 1. Application Circuit
Ci is required if regulator is located an appreciable distance from power supply filter.
Co improves stability and transient response.(Co > 47
F)
+
+
1
2
3
4
Vin
Vdis
Vo
GND
Disable Signal
Ci
Co
R
L
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