Fairchild Semiconductor KA278R33 Datasheet
KA278R33
Low Dropout Voltage Regulator
www.fairchildsemi.com
Features
• 2A / 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
Internal Block Diagram
1
Vin
Description
The KA278R33 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 KA278R33 is below 0.5V in full rated
current(2A). This regulator has various function such as
peak current protection, thermal shut down, overvoltage protection and output disable function.
TO-220F-4L
1
1. Vin 2. Vo 3. GND 4. Vdis
Q1
2
Vo
THERMAL SHUTDOWN
BANDGAP REFERENCE
HIGH / LOW OUTPUT
4
Vdis
1.4V
©2001 Fairchild Semiconductor Corporation
+
ON / OFF
OVERVOLTAGE
PROTECTION
+
SOA PROTECTION
SHORT-CIRCUIT
SHORTCIRCUIT
PROTECTION
3
GND
R1
R2
Rev.1.0.1
KA278R33
Absolute Maximum Ratings
Parameter Symbol Value Unit Remark
Input Voltage Vin 35 V Disable Voltage 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 -
Electrical Characteristics
(Vin=5V, Io=1.0A, Ta=25 °C, unless otherwise specified)
Parameter Symbol Conditions Min. Typ. Max. Unit
Output Voltage Vo - 3.22 3.3 3.38 V
Load Regulation Rload 5mA < Io < 2A - 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 = 2A - - 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 µA
Disable Bias Current Low IdisL Vdis = 0.4V - - -0.4 mA
Quiescent Current Iq Io = 0A - - 10 mA
Note:
1.These parameters, although guaranteed, are not 100% tested in production.
2
Typical Perfomance Characteristics
KA278R33
5.25
4.50
3.75
8
RL=
RL=3.3Ω
0 2 4 6 8 10
Output voltage Vo(V)
3.00
2.25
1.50
0.75
0
Input voltage Vin (V)
Figure 1.Output Voltage vs. Input Voltage
5.25
4.50
3.75
3.00
2.25
1.50
Output voltage Vo(V)
0.75
0
0
0.5 1.51 2 2.5
Disable voltage Vdis (V)
50
40
30
20
10
Quiescent current Iq(mA)
0
0
5
RL=
8
10
15
Input voltage Vin (V)
Figure 2.Quiescent Current vs. Input Voltage
3.36
3.34
3.32
3.30
3.28
3.26
Output voltage Vo(V)
3.24
3
3.22
-25
75
TEMPERATURE Tj(oC)
1250 25 50 100
Figure 3.Output Voltage vs. Disable Voltage
10
8
6
4
2
Quiescent current Iq(mA)
0
75 1250 25 50 100-25
Junction temperature Tj(oC)
Figure 5.Quiescent Current vs. Temperature(Tj)
Figure 4.Output Voltage vs. Temperature(Tj)
0.6
0.5
0.4
0.3
0.2
Dropout voltage Vdrop(V)
0.1
0
Io=2A
1.5A
1.0A
0.5A
750 25 50 100-25
125
Junction temperature Tj(oC)
Figure 6.Dropout Voltage vs. Junction Temperature
3
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