2001 Fairchild Semiconductor Corporation
www.fairchildsemi.com
Rev. 1.0.3
Features
1A / 3.3V Output low dropout voltage regulator
TO220 Full-Mold package (4PIN)
Overcurrent protection, Thermal shutdown
Overvoltage protection, Short-Circuit protection
With output disable function
Description
The KA78R33 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 KA78R33 is below 0.5V in full rated
current(1A). 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
-
CIRCUIT
KA78R33
Low Dropout Voltage Regulator
KA78R33
2
Absolute Maximum Ratings
Electrical Characteristics
(Vin=5V, Io=0.5A, 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 enviroments.
-. 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
1.0
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
4.31
C/W
-
Thermal Resistance, Junction-to-Air (Note2)
R
ja
48.83
C/W
-
Thermal Shutdown Temperature
Ttsd
150
C
-
Parameter
Symbol
Conditions
Min.
Typ.
Max.
Unit
Output Voltage
Vo
-
3.22
3.3
3.38
V
Load Regulation
Rload
5mA < Io < 1A
-
0.1
2.0
%
Line Regulation
Rline
4V < Vin < 10V
-
0.5
2.5
%
Ripple Rejection Ratio
RR
note1
45
55
-
dB
Dropout Voltage
Vdrop
Io = 1A
-
-
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
KA78R33
3
Typical Perfomance 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
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
tp
u
t
v
o
l
t
a
g
e
V
o
(
V
)
RL=
RL=3.3
8
0
O
u
t
put
vo
l
t
a
g
e
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
10
8
6
4
2
0
Q
u
es
c
e
nt
c
u
r
r
en
t
I
q
(
m
A
)
Junction temperature Tj(
o
C)
75
125
0
25
50
100
-25
i
50
40
30
20
10
0
Q
ues
ce
nt
cur
r
ent
I
q
(
m
A
)
Input voltage Vin (V)
RL=
0 2 4 6 8 10
8
i
3.34
3.32
3.30
3.36
-25
O
u
t
put
v
o
l
t
age
V
o
(
V
)
TEMPERATURE Tj(
o
C)
75
125
0
25
50
100
3.26
3.24
3.22
3.28
125
0.6
0.5
0.4
0.3
0
D
r
op
out
volt
ag
e
V
d
r
o
p
(
V
)
Junction temperature Tj(
o
C)
0.2
0.1
75
0
25
50
100
-25
Io=1A
0.75A
0.5A
0.25A
KA78R33
4
Typical Perfomance Characteristics (continued)
Figure 7. Power Dissipation vs. Temperature(Ta)
-25
P
o
w
e
r
di
s
s
i
p
at
i
o
n P
D
(W
)
TEMPERATURE T
J
(
o
C)
75
125
0
25
50
100
15
10
5
20
0
a
Output Current(A)
Rel
a
t
i
v
e
out
p
u
t
v
o
l
t
age(
%
)
1.5
2.5
0
0.5
1.0
2.0
80
60
20
100
0
40
3.0
Output Current(A)
Rel
a
t
i
v
e
out
p
u
t
v
o
l
t
age(
%
)
1.5
2.5
0
0.5
1.0
2.0
80
60
20
100
0
40
3.0
Rel
a
t
i
v
e
out
p
u
t
v
o
l
t
age(
%
)
1.5
2.5
0
0.5
1.0
2.0
80
60
20
100
0
40
3.0
Figure 8. Overcurrent Protection Characteristics
(Typical Value)
KA78R33
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
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