Fairchild Semiconductor KA78R33 Datasheet
KA78R33
Low Dropout Voltage Regulator
www.fairchildsemi.com
Features
• 1A / 3.3V Output low dropout voltage regulator
• TO220 Full-Mold package (4PIN)
• Overcurrent protection, T hermal shutdow n
• Overvoltag e protection, Short-Circuit protection
• With output disable function
Internal Block Diagram
1
Vin
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, overvolt age
protection and output disable functio n.
TO-220F-4L
1
1. Vin 2. Vo 3. GND 4. Vdis
Q1
2
Vo
THERMAL SHUTDOWN
BANDGAP REFERENCE
HIGH / LOW
4
Vdis
1.4V
©2001 Fairchild Semiconductor Corporation
+
OUTPUT
ON / OFF
OVERVOLTAGE
PROTECTION
+
SOA PROTECTION
CIRCUIT
-
SHORTCIRCUIT
PROTECTION
3
GND
R1
R2
Rev. 1.0.3
KA78R33
Absolute Maximum Ratings
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) Rθjc 4.31 °C/W -
Thermal Resistance, Junction-to-Air (Note2) Rθja 48.83 °C/W -
Thermal Shutdown Temperature Ttsd 150 °C-
Electrical Characteristics
(Vin=5V, Io=0.5A, 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 < 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 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. Junction to case thermal resistance test enviroments.
-. Pneumatic heat sink fixture.
-. Clamping pressure 60psi through 12mm diameter cyl ind er.
-. Thermal gr ease applied be tween PKG and h eat sink fixtur e
2
Typical Perfomance Characteristics
KA78R33
5.25
4.50
3.75
8
RL=
3.00
2.25
ΩΩΩΩ
1.50
Output voltage Vo(V)
0.75
0
0 2 4 6 8 10
RL=3.3
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
122.5
1.5
Disable voltage Vdis (V)
50
40
30
20
i
10
Quescent curr ent Iq ( m A )
0
0 2 4 6 8 10
RL=
8
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
02550
TEMPERATURE Tj(oC)
75
100
125
Figure 3. Output Voltage vs. Disable Voltage
10
8
6
4
i
2
Quesce nt current Iq(mA)
0
02550
-25
75
100
125
Junction temperature Tj(oC)
Figure 5. Quiescent Current vs. Temperature(Tj)
Figure 4. Output Voltage vs. Temper at ure(Tj)
0.6
0.5
0.4
0.3
0.2
Dropout voltage Vdrop(V)
0.1
0
02550
-25
Io=1A
0.75A
0.5A
0.25A
75
100
125
Junction temperature Tj(oC)
Figure 6. Dropout Voltage vs. Junction Temperature
3
Loading...