Fairchild Semiconductor KA378R12C Datasheet
KA378R12C
Low Dropout Voltage Regulator
www.fairchildsemi.com
Features
• 3A / 12V Output low dropout voltage regulator
• TO-220 Full-Mold package (4PIN)
• Overcurrent protection, T hermal shutdow n
• Overvoltage protection, Short Circuit protection
• With output disable function
Internal Block Diagram
1
Vin
THERMA L SHU TD OWN
Description
The KA378R12C 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 KA378R12C is below 0.5V in full rated
current(3A). 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
OVERVOLTAGE
PROTECTION
Q1
2
Vo
BANDGAP REFERENCE
HIGH / L OW
4
Vdis
1.4V
©2001 Fairchild Semiconductor Corporation
+
OUTPUT
ON / OFF
+
SOA PROTE CTION
SHORT-CIRCUIT
SHO RT CIRCUIT
PROTECTION
3
GND
R1
R2
Rev. 1.0.2
KA378R12C
Absolute Maximum Ratings
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) Rθjc 2.9 °C/W -
Thermal Shutdown Temperature Ttsd 150 °C-
Storage Temperature T
stg
-65 ~ 150 °C-
Electrical Characteristics
(Vin=15V, Io=1.5A, Ta=25°C, unless otherwise specified)
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 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 cylinder.
-.Thermal grease applied between PKG and heat sink fixture
2
Typical Perfomance Characteristics
KA378R12C
17.5
15.0
12.5
10.0
7.5
5.0
Output voltage Vo(V)
2.5
0
0
RL=
8
RL=4
ΩΩΩΩ
51015
20
Inpu t v olta ge V in (V )
Figure 1. Output Voltage vs. Input Voltage
17.5
15.0
12.5
10.0
7.5
5.0
Output voltage Vo(V)
2.5
0
0
122.5
1.5
Disable voltage Vdis (V)
100
80
60
40
20
Quiescent current Iq(mA)
25
0
510 15 20 25
0
RL=
8
Input voltage Vin (V)
Figure 2. Quiescent Current vs. Input Voltage
12.06
12.04
12.02
12.00
11.98
11.96
Output voltage Vo(V)
11.94
30.5
11.92
-25
02550
75
100
125
Temperature Tj(oC)
Figure 3. Output Voltage vs. Disable Voltage
10
8
6
4
2
Quiescent 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
Junction temperature Tj(oC)
Io= 3 A
2.0A
1.0A
0.5A
75
100
125
Figure 6. Dropout Voltage vs. Junction Temperature
3
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