www.fairchildsemi.com
KA78RXXC-Series
1A Output Low Dropout Voltage Regulators
Features
• 1A/3.3V, 5V, 8V, 9V, 12V, 15V 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 KA78RXXC 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. Dropout voltage of KA78RXXC is
below 0.5V in full rated current(1A).
This regulator has various functions such as peak current
protection, thermal shut down, overvoltage protection and
output disable function.
TO-220F-4L
1
1. Vin 2. V
O
3. GND 4. Vdis
Internal Block Diagram
Q1
Vin
1
2
Vo
THERMAL SHUTDOWN
OVERVOLTAGE
PROTECTION
BANDGAP REFERENCE
-
+
R1
SOA PROTECTION
HIGH / LOW
Vdis
4
-
+
OUTPUT
ON / OFF
R2
1.4V
SHORT-CIRCUIT
SHORTCIRCUIT
PROTECTION
3
GND
Rev. 1.0.0
©2003 Fairchild Semiconductor Corporation
KA78RXXC-SERIES
Absolute Maximum Ratings
KA78RXXC
Parameter
Input voltage
Disable voltage
Output current
Power dissipation 1
Power dissipation 2
Junction temperature
Operating temperature
Thermal resistance, junction-to case (Note2)
Thermal resistance, junction-to-air (Note2)
Symbol
Vin
Vdis
Io
Pd1
Pd2
Tj
Topr
Rθjc
Rθja
Value
35
35
1.0
1.5
15
+150
-20 ~ +80
4.31
48.83
Unit
V
V
A
W
W
°C
°C
°C/W
°C/W
Remark
-
-
-
No heatsink
With heatsink
-
-
-
-
2
KA78RXXC-SERIES
Electrical Characteristics
(Vin = Note3, Io = 0.5A, Ta = 25°C, unless otherwise specified)
Parameter
KA78R33C
KA78R05C
Output voltage
KA78R08C
KA78R09C
KA78R12C
KA78R15C
Load regulation
Line regulation
Ripple rejection ratio
Dropout voltage
Disable voltage high
Disable voltage low
Disable bias current high
Disable bias current low
Quiescent current
Rload
Rline
RR
Vdrop
VdisH
VdisL
IdisH
IdisL
Iq
Note4
Note1
Io = 1A
Output active
Output disabled
Vdis = 2.7V
Vdis = 0.4V
Io = 0A
Vo
Symbol
Conditions
-
-
-
-
-
-
5mA < Io < 1A
Min.
3.22
4.88
7.8
8.78
11.7
14.6
-
-
45
-
2.0
-
-
-
-
Typ.
3.3
5
8
9
12
15
0.1
0.5
55
-
-
-
-
-
-
Max.
3.38
5.12
8.2
9.22
12.3
15.4
2.0
2.5
-
0.5
-
0.8
20
-0.4
10
%
%
dB
V
V
V
µA
mA
mA
V
Unit
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. KA78R33C :Vin = 5V
KA78R05C : Vin = 7V
KA78R08C : Vin = 10V
KA78R09C : Vin = 11V
KA78R12C : Vin = 15V
KA78R15C : Vin = 20V
4. KA78R33C :Vin = 4V to 10V
KA78R05C : Vin = 6V to 12V
KA78R08C : Vin = 9V to 25V
KA78R09C : Vin = 10V to 25V
KA78R12C : Vin = 13V to 29V
KA78R15C : Vin = 16V to 30V
3
KA78RXXC-SERIES
Typical Performance Characteristics
KA78R33
5.25
80
Output voltage Vo(V)
4.50
3.75
3.00
2.25
1.50
0.75
0
RL=3.3Ω
Ω
RL=
8
Quiescent current Iq(mA)
60
40
20
RL=
∞
0
5
10
Input voltage Vin(V)
15
20
0
0
2
4
6
8
10
Input voltage Vin (V)
Figure 1. Output Voltage vs. Input Voltage
5.25
Figure 2. Quiescent Current vs. Input Voltage
3.36
Output voltage Vo(V)
Output voltage Vo(V)
0
0.5
1
1.5
2
2.5
3
4.50
3.75
3.00
2.25
1.50
0.75
0
3.34
3.32
3.30
3.28
3.26
3.24
3.22
-25
0
Disable voltage Vdis (V)
75
25
50
TEMPERATURE Tj(
o
C)
100
125
Figure 3. Output Voltage vs. Disable Voltage
10
Figure 4. Output Voltage vs. Temperature(Tj)
Quescent current Iq(mA)
0.55
8
Drop out voltage Vdrop [V]
0.50
0.45
0.40
0.35
0.30
0.25
0.20
-25
0
25
50
75
100
125
1.0A
6
4
2
0
-25
0
25
50
75
100
125
Junction temperature Tj(
o
C)
Junction Temp Tj [
℃
]
Figure 5. Quiescent Current vs. Temperature(Tj)
Figure 6. Dropout Voltage vs.Junction Temperature
4
KA78RXXC-SERIES
Typical Performance Characteristics
(Continued)
20
100
Power dissipation P
D
(W)
Relative output voltage(%)
80
60
15
10
40
5
20
0
-25
0
0
25
50
75
o
100
125
0
0.5
1.0
1.5
2.0
2.5
3.0
TEMPERATURE T
J
( C)
Output Current(A)
Figure 7. Power Dissipation vs. Temperature(Tj)
Figure 8. Overcurrent Protection Characteristics
(Typical Value)
2.75
Output peak current Iop (A)
2.50
2.25
2.00
1.75
1.50
0
1
2
3
4
5
6
Input-output differential voltage Vin-Vo (V)
Figure 9. Output Peak Currenrt vs.
Input-Output Differential Voltage
5
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