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KA278R51
Low Dropout Voltage Regulator
Features
* * * * * 2A / 5.1V 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 KA278R51 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 KA278R51 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
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. 1.0.1
(c)2001 Fairchild Semiconductor Corporation
KA278R51
Absolute Maximum Ratings
Parameter Input Voltage Disable Voltage Output Current Power Dissipation 1 Power Dissipation 2 Junction Temperature Operating Temperature Symbol Vin Vdis Io Pd1 Pd2 Tj Topr Value 35 35 2.0 1.5 15 +150 -20 ~ +80 Unit V V A W W C C Remark No Heatsink With Heatsink -
Electrical Characteristics
(Vin=7V, Io=1.0A, Ta = +25C, unless otherwise specified) Parameter Output Voltage 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 Symbol Vo Rload Rline RR Vdrop VdisH VdisL IdisH IdisL Iq 5mA < Io < 2A 6V < Vin < 12V note1 Io = 2A Output Active Output Disabled Vdis = 2.7V Vdis = 0.4V Io = 0A Conditions Min. 4.98 45 2.0 Typ. 5.1 0.1 0.5 55 Max. 5.22 2.0 2.5 0.5 0.8 20 -0.4 10 Unit V % % dB V V V A mA mA
Note: 1.These parameters, although guaranteed, are not 100% tested in production.
2
KA278R51
Typical Perfomance Characteristics
7 50
Output voltage Vo(V)
6 5
RL= 8
i Quescent current Iq(mA)
40
4
RL=2.5
30
3 2 1 0 0 5 10 15
20
RL=
0
8
10
0
5
10
15
Input voltage Vin (V)
Input voltage Vin (V)
Figure 1.Output Voltage vs. Input Voltage
Figure 2.Quiescent Current vs. Input Voltage
7
5.16 5.14 5.12 5.10 5.08 5.06 5.04 5.02 -25
Output voltage Vo(V)
6 5 4 3 2 1 0
0
0.5
1
1.5
2
2.5
3
Output voltage Vo(V)
0
25
50
75
100
125
Disable voltage Vdis (V)
TEMPERATURE Tj(oC)
Figure 3.Output Voltage vs. Disable Voltage
Figure 4.Output Voltage vs. Temperature(Tj)
Quescent current Iq(mA) i
Dropout voltage Vdrop (V)
10 8
0.6 0.5 0.4 Io=2A 0.3 1.5A 0.2 1.0A 0.1 0.5A 0 -25
6
4
2
0
-25
0
25
50
75
100
125
0
25
50
75
100
125
Junction temperature Tj(o C)
Junction temperature Tj (o C)
Figure 5.Quiescent Current vs. Temperature(Tj)
Figure 6.Dropout Voltage vs. Junction Temperature
3
KA278R51
Typical Perfomance Characteristics (continued)
20 100
Relative output voltage(%)
Power dissipation PD(W)
80 60
15
10
40
5
20
0 -25
0 0 1.0 2.0
3.0
4.0
5.0
6.0
a TEMPERATURE Tj(o C)
Output Current(A)
Figure 7.Power Dissipation vs. Temperature(Ta)
Figure 8.Overcurrent Protection Characteristics(Typical value)
70
Ripple Rejection RR (dB)
60 50 40 30 20 10 0 Tj = 25 oC VIN = 7V IO =1A VIN = 0.5Vrms 0.1 1 10 100
Input Voltage (V)
30 25 20 15 10 5 0 -5 -10 -15 -20 -25 8
Output Voltage Deviation (mV)
7
0
5
15
25
35
45
Input Ripple Frequency (KHz)
Time (s)
Figure 9.Ripple Rejection vs. Input Ripple Frequency
Figure 10.Line Transient Response
Output Current (A)
3.0 2.5 2.0 1.5 1.0 0.5 0.0 -0.5 -1.0 -1.5 -2.0 -2.5 2.0
Output Voltage Deviation (V)
0
0
10
20
30
40
Time (s)
Figure 11.Load Transient Response
4
KA278R51
Typical Application
Vin 1
+
Vo 2
+
Ci
3 GND 4 Vdis Disable Signal
Co
RL
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)
5
KA278R51
Mechanical Dimensions
Package Dimensions in millimeters
TO-220F-4L
6
KA278R51
Ordering Information
Product Number KA278R51 Package TO-220F-4L Operating Temperature -20 C to + 80C
7
KA278R51
DISCLAIMER FAIRCHILD SEMICONDUCTOR RESERVES THE RIGHT TO MAKE CHANGES WITHOUT FURTHER NOTICE TO ANY PRODUCTS HEREIN TO IMPROVE RELIABILITY, FUNCTION OR DESIGN. FAIRCHILD DOES NOT ASSUME ANY LIABILITY ARISING OUT OF THE APPLICATION OR USE OF ANY PRODUCT OR CIRCUIT DESCRIBED HEREIN; NEITHER DOES IT CONVEY ANY LICENSE UNDER ITS PATENT RIGHTS, NOR THE RIGHTS OF OTHERS. LIFE SUPPORT POLICY FAIRCHILD'S PRODUCTS ARE NOT AUTHORIZED FOR USE AS CRITICAL COMPONENTS IN LIFE SUPPORT DEVICES OR SYSTEMS WITHOUT THE EXPRESS WRITTEN APPROVAL OF THE PRESIDENT OF FAIRCHILD SEMICONDUCTOR CORPORATION. As used herein: 1. Life support devices or systems are devices or systems which, (a) are intended for surgical implant into the body, or (b) support or sustain life, and (c) whose failure to perform when properly used in accordance with instructions for use provided in the labeling, can be reasonably expected to result in a significant injury of the user.
www.fairchildsemi.com 4/26/01 0.0m 001 Stock#DSxxxxxxxx (c) 2001 Fairchild Semiconductor Corporation
2. A critical component in any component of a life support device or system whose failure to perform can be reasonably expected to cause the failure of the life support device or system, or to affect its safety or effectiveness.

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