MC78T05C [ONSEMI]
THREE-AMPERE POSITIVE FIXED VOLTAGE REGULATORS; 三，安培固定正稳压器
| 型号： | MC78T05C |
| 厂家： | 
ONSEMI |
| 描述： | THREE-AMPERE POSITIVE FIXED VOLTAGE REGULATORS |
| 文件： | 总12页 (文件大小：166K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Order this document by MC78T00/D
This family of fixed voltage regulators are monolithic integrated circuits
capable of driving loads in excess of 3.0 A. These three–terminal regulators
employ internal current limiting, thermal shutdown, and safe–area
compensation. Devices are available with improved specifications, including
a 2% output voltage tolerance, on AC–suffix 5.0, 12 and 15 V device types.
Although designed primarily as a fixed voltage regulator, these devices
can be used with external components to obtain adjustable voltages and
currents. This series of devices can be used with a series–pass transistor to
supply up to 15 A at the nominal output voltage.
THREE–AMPERE
POSITIVE FIXED
VOLTAGE REGULATORS
SEMICONDUCTOR
TECHNICAL DATA
• Output Current in Excess of 3.0 A
• Power Dissipation: 25 W
• No External Components Required
• Output Voltage Offered in 2% and 4% Tolerance*
• Thermal Regulation is Specified
• Internal Thermal Overload Protection
• Internal Short Circuit Current Limiting
• Output Transistor Safe–Area Compensation
T SUFFIX
PLASTIC PACKAGE
CASE 221A
Pin 1. Input
2. Ground
3. Output
2
MAXIMUM RATINGS (T = +25°C, unless otherwise noted.)
1
A
3
Rating
Symbol
Value
Unit
Input Voltage (5.0 V – 12 V)
Input Voltage (15 V)
V
I
35
40
Vdc
Heatsink surface is connected to Pin 2.
Power Dissipation and Thermal Characteristics
Plastic Package (Note 1)
T
= +25°C
P
InternallyLimited
A
D
Thermal Resistance, Junction–to–Air
= +25°C
R
P
R
65
InternallyLimited
2.5
°C/W
θJA
D
T
C
Thermal Resistance, Junction–to–Case
°C/W
°C
θJC
Storage Junction Temperature
T
stg
+150
Operating Junction Temperature Range
(MC78T00C, AC)
T
J
0 to +125
°C
DEVICE TYPE/NOMINAL OUTPUT VOLTAGE
MC78T05
MC78T08
5.0 V
8.0 V
MC78T12
MC78T15
12 V
15 V
NOTES: 1. Although power dissipation is internally limited, specifications apply only
for P ≤ P , P = 25 W.
O
max max
ORDERING INFORMATION
Operating
Simplified Application
V
Temperature
Range
O
Tol.
Device
Package
MC78TXX
Output
Input
T = 0° to
+125°C
Plastic
Power
MC78TXXCT
MC78TXXACT
4%
2%*
J
C
*
in
0.33µF
C **
O
T = –40° to
+125°C
Plastic
Power
MC78TXXBT#
MC78TXXABT# 2%*
4%
J
XX Indicates nominal voltage.
A common ground is required between the input and the output voltages. The input voltage must
remain typically 2.2 V above the output voltage even during the low point on the input ripple voltage.
* 2% regulators available in 5, 12 and 15 V devices.
XX these two digits of the type number indicate voltage.
# Automotive temperature range selections are avail-
able with special test conditions and additional
tests. Contact your local Motorola sales office for
information.
** C is required if regulator is located an appreciable distance from power supply filter.
in
** (See Applications Information for details.)
** C is not needed for stability; however, it does improve transient response.
O
Motorola, Inc. 1996
Rev 1
MC78T00 Series
ELECTRICAL CHARACTERISTICS (V = 10 V, I = 3.0 A, 0°C ≤ T ≤ 125°C, P ≤ P
[Note 1], unless otherwise noted.)
in
O
J
O
max
MC78T05AC
MC78T05C
Characteristics
Symbol
Min
Typ
Max
Min
Typ
Max
Unit
Output Voltage
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
V
O
Vdc
4.9
4.8
5.0
5.0
5.1
5.2
4.8
4.75
5.0
5.0
5.2
5.25
O
J
(5.0 mA ≤ I ≤ 3.0 A;
O
5.0 mA ≤ I ≤ 2.0 A, 7.3 Vdc ≤ V ≤ 20 Vdc)
O
in
Line Regulation (Note 2)
Reg
–
3.0
25
–
3.0
25
mV
mV
line
(7.2 Vdc ≤ V ≤ 35 Vdc, I = 5.0 mA, T = +25°C;
in
O
O
O
O
J
7.2 Vdc ≤ V ≤ 35 Vdc, I = 1.0 A, T = +25°C;
in
J
J
8.0 Vdc ≤ V ≤ 12 Vdc, I = 3.0 A, T = +25°C;
in
7.5 Vdc ≤ V ≤ 20 Vdc, I = 1.0 A)
in
Load Regulation (Note 2)
Reg
load
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
10
15
30
80
–
–
10
15
30
80
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Thermal Regulation
(Pulse = 10 ms, P = 20 W, T = +25°C)
Reg
–
0.001
0.01
–
0.002
0.03
%V /W
O
therm
A
Quiescent Current
I
mA
mA
B
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
3.5
4.0
5.0
6.0
–
–
3.5
4.0
5.0
6.0
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Quiescent Current Change
∆I
–
0.3
1.0
–
0.3
1.0
B
(7.2 Vdc ≤ V ≤ 35 Vdc, I = 5.0 mA, T = +25°C;
in
O
J
5.0 mA ≤ I ≤ 3.0 A, T = +25°C;
O
J
7.5 Vdc ≤ V ≤ 20 Vdc, I = 1.0 A)
in
O
Ripple Rejection
RR
62
75
–
62
75
–
dB
(8.0 Vdc ≤ V ≤ 18 Vdc, f = 120 Hz,
in
I
O
= 2.0 A, T = 25°C)
J
Dropout Voltage (I = 3.0 A, T = +25°C)
V –V
in O
–
–
2.2
10
2.5
–
–
–
2.2
10
2.5
–
Vdc
O
J
Output Noise Voltage
V
n
µV/V
O
(10 Hz ≤ f ≤ 100 kHz, T = +25°C)
J
Output Resistance (f = 1.0 kHz)
R
–
–
2.0
1.5
–
–
–
–
20
–
–
mΩ
O
Short Circuit Current Limit
I
1.5
A
SC
(V = 35 Vdc, T = +25°C)
in
J
Peak Output Current (T = +25°C)
I
–
–
5.0
0.2
–
–
–
–
5.0
0.2
–
–
A
J
max
Average Temperature Coefficient of Output Voltage
(I = 5.0 mA)
TCV
mV/°C
O
O
NOTES: 1. Although power dissipation is internally limited, specifications apply only for P ≤ P
, P = 25 W.
max max
O
2. Line and load regulation are specified at constant junction temperature. Changes in V due to heating effects must be taken into account separately.
O
Pulse testing with low duty cycle is used.
2
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
ELECTRICAL CHARACTERISTICS (V = 13 V, I = 3.0 A, 0°C ≤ T ≤ 125°C, P ≤ P
[Note 1], unless otherwise noted.)
in
O
J
O
max
MC78T08C
Characteristics
Symbol
Min
Typ
Max
Unit
Output Voltage
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
V
O
Vdc
7.7
7.6
8.0
8.0
8.3
8.4
O
J
(5.0 mA ≤ I ≤ 3.0 A;
O
5.0 mA ≤ I ≤ 2.0 A, 10.4 Vdc ≤ V ≤ 23 Vdc)
O
in
Line Regulation (Note 2)
Reg
–
4.0
35
mV
mV
line
(10.3 Vdc ≤ V ≤ 35 Vdc, I = 5.0 mA, T = +25°C
in
O
O
J
10.3 Vdc ≤ V ≤ 35 Vdc, I = 1.0 A, T = +25°C
in
J
11 Vdc ≤ V ≤ 17 Vdc, I = 3.0 A, T = +25°C
in
O
J
10.7 Vdc ≤ V ≤ 23 Vdc, I = 1.0 A)
in
O
Load Regulation (Note 2)
Reg
load
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
10
15
30
80
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Thermal Regulation
(Pulse = 10 ms, P = 20 W, T = +25°C)
Reg
–
0.002
0.03
%V /W
O
therm
A
Quiescent Current
I
mA
mA
B
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
3.5
4.0
5.0
6.0
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Quiescent Current Change
∆I
–
0.3
1.0
B
(10.3 Vdc ≤ V ≤ 35 Vdc, I = 5.0 mA, T = +25°C;
in
O
J
5.0 mA ≤ I ≤ 3.0 A, T = +25°C;
O
J
10.7 Vdc ≤ V ≤ 23 Vdc, I = 1.0 A)
in
O
Ripple Rejection
(11 Vdc ≤ V ≤ 21 Vdc, f = 120 Hz, I = 2.0 A, T = 25°C)
RR
60
71
–
dB
in
O
J
Dropout Voltage (I = 3.0 A, T = +25°C)
V –V
in O
–
–
2.2
10
2.5
–
Vdc
O
J
Output Noise Voltage
V
n
µV/V
O
(10 Hz ≤ f ≤ 100 kHz, T = +25°C)
J
Output Resistance (f = 1.0 kHz)
R
–
–
2.0
1.5
–
–
mΩ
O
Short Circuit Current Limit
I
A
SC
(V = 35 Vdc, T = +25°C)
in
J
Peak Output Current (T = +25°C)
I
–
–
5.0
0.3
–
–
A
J
max
Average Temperature Coefficient of Output Voltage (I = 5.0 mA)
TCV
mV/°C
O
O
NOTES: 1. Although power dissipation is internally limited, specifications apply only for P ≤ P
, P = 25 W.
max max
O
2. Line and load regulation are specified at constant junction temperature. Changes in V due to heating effects must be taken into account separately.
O
Pulse testing with low duty cycle is used.
3
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
ELECTRICAL CHARACTERISTICS (V = 17 V, I = 3.0 A, 0°C ≤ T ≤ 125°C, P ≤ P
[Note 1], unless otherwise noted.)
in
O
J
O
max
MC78T12AC
MC78T12C
Characteristics
Symbol
Min
Typ
Max
Min
Typ
Max
Unit
Output Voltage
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
V
O
Vdc
11.75
11.5
12
12
12.25
12.5
11.5
11.4
12
12
12.5
12.6
O
J
(5.0 mA ≤ I ≤ 3.0 A,
O
5.0 mA ≤ I ≤ 2.0 A, 14.5 Vdc ≤ V ≤ 27 Vdc)
O
in
Line Regulation (Note 2)
Reg
–
6.0
45
–
6.0
45
mV
mV
line
(14.5 Vdc ≤ V ≤ 35 Vdc, I = 5.0 mA, T = +25°C;
in
O
O
J
14.5 Vdc ≤ V ≤ 35 Vdc, I = 1.0 A, T = +25°C;
in
J
16 Vdc ≤ V ≤ 22 Vdc, I = 3.0 A, T = +25°C;
in
O
J
14.9 Vdc ≤ V ≤ 27 Vdc, I = 1.0 A)
in
O
Load Regulation (Note 2)
Reg
load
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
10
15
30
80
–
–
10
15
30
80
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Thermal Regulation
(Pulse = 10 ms, P = 20 W, T = +25°C)
Reg
–
0.001
0.01
–
0.002
0.03
%V /W
O
therm
A
Quiescent Current
I
mA
mA
B
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
3.5
4.0
5.0
6.0
–
–
3.5
4.0
5.0
6.0
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Quiescent Current Change
∆I
–
0.3
1.0
–
0.3
1.0
B
(14.5 Vdc ≤ V ≤ 35 Vdc, I = 5.0 mA, T = +25°C;
in
O
J
5.0 mA ≤ I ≤ 3.0 A, T = +25°C;
O
J
14.9 Vdc ≤ V ≤ 27 Vdc, I = 1.0 A)
in
O
Ripple Rejection
RR
57
67
–
57
67
–
dB
(15 Vdc ≤ V ≤ 25 Vdc, f = 120 Hz,
in
= 2.0 A, T = 25°C)
I
O
J
Dropout Voltage (I = 3.0 A, T = +25°C)
V
in
– V
O
–
–
2.2
10
2.5
–
–
–
2.2
10
2.5
–
Vdc
O
J
Output Noise Voltage
V
n
µV/V
O
(10 Hz ≤ f ≤ 100 kHz, T = +25°C)
J
Output Resistance (f = 1.0 kHz)
R
–
–
2.0
1.5
–
–
–
–
20
–
–
mΩ
O
Short Circuit Current Limit
I
1.5
A
SC
(V = 35 Vdc, T = +25°C)
in
J
Peak Output Current (T = +25°C)
I
–
–
5.0
0.5
–
–
–
–
5.0
0.5
–
–
A
J
max
Average Temperature Coefficient
TCV
mV/°C
O
of Output Voltage (I = 5.0 mA)
O
NOTES: 1. Although power dissipation is internally limited, specifications apply only for P ≤ P
, P
max max
O
= 25 W.
O
2. Line and load regulation are specified at constant junction temperature. Changes in V due to heating effects must be taken into account separately.
Pulse testing with low duty cycle is used.
4
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
ELECTRICAL CHARACTERISTICS (V = 20 V, I = 3.0 A, 0°C ≤ T ≤ 125°C, P ≤ P
[Note 1], unless otherwise noted.)
in
O
J
O
max
MC78T15AC
MC78T15C
Characteristics
Symbol
Min
Typ
Max
Min
Typ
Max
Unit
Output Voltage
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
V
O
Vdc
14.7
14.4
15
15
15.3
15.6
14.4
14.25
15
15
15.6
15.75
O
J
(5.0 mA ≤ I ≤ 3.0 A;
O
5.0 mA ≤ I ≤ 2.0 A, 17.5 Vdc ≤ V ≤ 30 Vdc)
O
in
Line Regulation (Note 2)
Reg
–
7.5
55
–
7.5
55
mV
mV
line
(17.6 Vdc ≤ V ≤ 40 Vdc, I = 5.0 mA, T = +25°C;
in
O
O
J
17.6 Vdc ≤ V ≤ 40 Vdc, I = 1.0 A, T = +25°C;
in
J
20 Vdc ≤ V ≤ 26 Vdc, I = 3.0 A, T = +25°C;
in
O
O
J
18 Vdc ≤ V ≤ 30 Vdc, I = 1.0 A)
in
Load Regulation (Note 2)
Reg
load
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
10
15
30
80
–
–
10
15
30
80
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Thermal Regulation
(Pulse = 10 ms, P = 20 W, T = +25°C)
Reg
–
0.001
0.01
–
0.002
0.03
%V /W
O
therm
A
Quiescent Current
I
mA
mA
B
(5.0 mA ≤ I ≤ 3.0 A, T = +25°C)
–
–
3.5
4.0
5.0
6.0
–
–
3.5
4.0
5.0
6.0
O
J
(5.0 mA ≤ I ≤ 3.0 A)
O
Quiescent Current Change
∆I
–
0.3
1.0
–
0.3
1.0
B
(17.6 Vdc ≤ V ≤ 40 Vdc, I = 5.0 mA, T = +25°C;
in
O
J
5.0 mA ≤ I ≤ 3.0 A, T = +25°C;
O
J
18 Vdc ≤ V ≤ 30 Vdc, I = 1.0 A)
in
O
Ripple Rejection
RR
55
65
–
55
65
–
dB
(18.5 Vdc ≤ V ≤ 28.5 Vdc, f = 120 Hz,
in
I
O
= 2.0 A, T = 25°C)
J
Dropout Voltage (I = 3.0 A, T = +25°C)
V –V
in O
–
–
2.2
10
2.5
–
–
–
2.2
10
2.5
–
Vdc
O
J
Output Noise Voltage
V
n
µV/V
O
(10 Hz ≤ f ≤ 100 kHz, T = +25°C)
J
Output Resistance (f = 1.0 kHz)
R
–
–
2.0
1.0
–
–
–
–
20
–
–
mΩ
O
Short Circuit Current Limit
I
1.0
A
SC
(V = 40 Vdc, T = +25°C)
in
J
Peak Output Current (T = +25°C)
I
–
–
5.0
0.6
–
–
–
–
5.0
0.6
–
–
A
J
max
Average Temperature Coefficient of Output Voltage
(I = 5.0 mA)
TCV
mV/°C
O
O
NOTES: 1. Although power dissipation is internally limited, specifications apply only for P ≤ P
, P
max max
O
= 25 W.
O
2. Line and load regulation are specified at constant junction temperature. Changes in V due to heating effects must be taken into account separately.
Pulse testing with low duty cycle is used.
5
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
VOLTAGE REGULATOR PERFORMANCE
The performance of a voltage regulator is specified by its
can be caused by a change in either the input voltage or the
load current. Thermal regulation is a function of IC layout and
die attach techniques, and usually occurs within 10 ms of a
change in power dissipation. After 10 ms, additional changes
in the output voltage are due to the temperature coefficient of
the device.
Figure 1 shows the line and thermal regulation response of
a typical MC78T05AC to a 20 W input pulse. The variation of
the output voltage due to line regulation is labeled ➀ and the
thermal regulation component is labeled ➁. Figure 2 shows
the load and thermal regulation response of a typical
MC78T05AC to a 20 W load pulse. The output voltage
variation due to load regulation is labeled ➀ and the thermal
regulation component is labeled ➁.
immunity to changes in load, input voltage, power dissipation,
and temperature. Line and load regulation are tested with a
pulse of short duration (< 100µs) and are strictly a function of
electrical gain. However, pulse widths of longer duration (>
1.0 ms) are sufficient to affect temperature gradients across
the die. These temperature gradients can cause a change in
the output voltage, in addition to changes caused by line and
load regulation. Longer pulse widths and thermal gradients
make it desirable to specify thermal regulation.
Thermal regulation is defined as the change in output
voltage caused by a change in dissipated power for a
specified time, and is expressed as a percentage output
voltage change per watt. The change in dissipated power
Figure 1. MC78T05AC Line and Thermal Regulation
Figure 2. MC78T05AC Load and Thermal Regulation
2
2
2
1
2
1
18
2.0
8.0
0
t, TIME (2.0 ms/DIV)
t, TIME (2.0 ms/DIV)
V
= 5.0 V
V
= 5.0 V
out
out
1
2
= Reg
= Reg
= 2.4 mV
1
2
= Reg
= 4.4 mV
line
line
V
I
= 8.0 V
→
18 V
→
8.0 V
V
I
= 15
in
in
= 2.0 A
= 0 A
→
2.0 A → 0 A
= 0.0015%V /W
= Reg
= 0.0015%V /W
out
out
therm
O
therm
O
Representative Schematic Diagram
Input
1.0k
1.0k
Q1
Q2
Q21
Q20
210
Q22
6.7V
16k
100
200
Q24
Q25
Q9
Q26
13
1.0k
Q8
300
Q3
Q27
0.12
3.0k
10pF
3.6k
6.4k
Q4
Q19
Q23
5.6k
Q16
300
Q5
Q10
200
50
Output
520
40
pF
Q12
2.6k
8.0–15 V
O
6.0k
Q17
Q18
5.0 V
O
2.0k
Q11
3.9k
Q6
Q7
Q13
6.0k
Q15
2.8k
Gnd
Q14
6
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
Figure 3. Temperature Stability
Figure 4. Output Impedance
0
1.02
1.0
10
V
I
– V
= 10 V
= 100 mA
1
in
out
10–
10–
out
V
V
= 5.0 V
out
in
= 7.5 V
= 1.0 A
= 0
I
C
2
out
O
J
T
= 25
°C
3
10–
10–
4
.98
–90
–50
–10
30
70
110
150
190
1.0
10
100
1.0 k
10 k 100 k
1.0 M
10 M 100 M
T , JUNCTION TEMPERATURE (°C)
f, FREQUENCY (Hz)
J
Figure 6. Ripple Rejection versus
Output Current
Figure 5. Ripple Rejection versus Frequency
100
80
100
80
60
40
20
I
= 50 mA
out
I
= 1.5 A
out
V
out
= 5.0 V
= 10 V
= 0
V
= 5.0 V
= 10 V
= 0
= 25°C
out
60
V
in
V
in
C
O
C
O
f = 120 Hz
= 25°C
T
J
T
J
40
30
0.01
0.1
1.0
10
1.0
10
100 1.0 k
10 k
100 k
1.0 M
10 M 100 M
f, FREQUENCY (Hz)
I
, OUTPUT CURRENT (A)
out
Figure 7. Quiescent Current versus
Input Voltage
Figure 8. Quiescent Current versus
Output Current
4.0
5.0
4.0
3.0
2.0
1.0
0
T
= 0°C
J
T
= 25°C
J
T
= 0°C
J
3.0
2.0
T
= 125°C
J
T
= 25°C
J
T
= 125°C
J
1.0
0
T
T
T
= 0°C
J
J
J
V
–V = 5.0 V
in out
= 25°C
= 125
°C
0
10
20
, INPUT VOLTAGE (Vdc)
30
40
0.01
0.1
I , OUTPUT CURRENT (A)
out
1.0
10
V
in
7
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
Figure 9. Dropout Voltage
Figure 10. Peak Output Current
2.5
2.0
1.5
1.0
0.5
8.0
6.0
4.0
2.0
0
I
= 3.0 A
out
I
= 1.0 A
out
I
= 0.5 A
out
T
T
T
= 0°C
J
J
J
∆V
= 50 mV
–10
O
= 25
°C
= 125
°
C
–90
–50
30
70
110
C)
150
190
0
10
V –V , INPUT–OUTPUT VOLTAGE (Vdc)
in
20
30
40
T , JUNCTION TEMPERATURE (
°
J
O
Figure 11. Line Transient Response
Figure 12. Load Transient Response
0.8
0.6
0.4
0.2
0.3
V
= 5.0 V
= 150 mA
= 0
V
C
T
= 10 V
= 0
= 25°C
out
in
O
J
0.2
0.1
I
out
C
O
T
= 25°C
J
0
–0.1
0
–0.2
–0.3
–0.2
–0.4
–0.6
1.5
1.0
1.0
0.5
0
0.5
0
0
10
20
t, TIME (µs)
30
40
0
10
20
30
40
t, TIME (µs)
Figure 13. Maximum Average Power
Dissipation for MC78T00CT, ACT
40
30
Maximum Ambient
Temperature
θ
of Heatsinks
SA
1.3°C/W
2.4°C/W
Infinite
20
Heatsink
3.3°C/W
10
0
6.3
°
C/W
10.5
°
C
25
50
75
100
C)
125
T , AMBIENT TEMPERATURE (
°
A
8
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
APPLICATIONS INFORMATION
Design Considerations
regulator is connected to the power supply filter with long wire
lengths, or if the output load capacitance is large. An input
bypass capacitor should be selected to provide good high
frequency characteristics to insure stable operation under all
load conditions. A 0.33 µF or larger tantalum, mylar, or other
capacitor having low internal impedance at high frequencies
should be chosen. The bypass capacitor should be mounted
with the shortest possible leads directly across the regulator’s
input terminals. Normally good construction techniques
should be used to minimize ground loops and lead resistance
drops since the regulator has no external sense lead.
The MC78T00 Series of fixed voltage regulators are
designed with Thermal Overload Protection that shuts down
the circuit when subjected to an excessive power overload
condition, Internal Short Circuit Protection that limits the
maximum current the circuit will pass, and Output Transistor
Safe–Area Compensation that reduces the output short
circuit current as the voltage across the pass transistor is
increased.
In many low current applications, compensation
capacitors are not required. However, it is recommended that
the regulator input be bypassed with a capacitor if the
Figure 14. Current Regulator
Figure 15. Adjustable Output Regulator
MC78T05
Input
0.33
Output
MC78T05
R
µF
Input
Constant
Current to
Grounded Load
I
O
7
4
2
3
The MC78T05 regulator can also be used as a current source when
connectedas above. In order to minimize dissipation the MC78T05 is
–
+
0.33
µ
F
0.1µF
6
chosen in this application. Resistor
R
determines the current
as follows:
10k
5.0 V
R
1.0k
I
=
+ I
O
B
MC1741
∆
I
I
0.7 mA over line, load and Temperature changes
3.5 mA
B
B
V
V
, 8.0 V to 20 V
O
– V ≥ 2.5 V
in
O
For example, a 2.0 A current source would require R to be a 2.5
Ω,
Theadditionofanoperationalamplifierallowsadjustmenttohigheror
intermediate values while retaining regulation characteristics. The
minimum voltage obtainable with this arrangement is 3.0 V greater
than the regulator voltage.
10 W resistor and the output voltage compliance would be the input
voltage less 7.0 V.
Figure 17. Current Boost With
Short Circuit Protection
Figure 16. Current Boost Regulator
2N4398
or Equiv.
2N4398 or Equiv
Input
R
sc
R
MC78TXX
Output
MJ2955
or Equiv.
R
MC78TXX
1.0µF
0.1µF
Output
1.0µF
XX = 2 digits of type number indicating voltage.
The MC78T00 series can be current boosted with a PNP transistor. The
XX = 2 digits of type number indicating voltage.
The circuit of Figure 17 can be modified to provide supply protection
2N4398providescurrentto15A.ResistorRinconjuctionwiththeV of
BE
the PNP determines when the pass transistor begins conducting; this
circuit is not short circuit proof. Input–output differential voltage
against short circuits by adding a short circuit sense resistor, R , and
SC
an additional PNP transistor. The current sensing PNP must be able to
handle the short circuit current of the three–terminal regulator.
Therefore, an eight–ampere power transistor is specified.
minimum is increased by the V
of the pass transistor.
BE
9
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
OUTLINE DIMENSIONS
T SUFFIX
PLASTIC PACKAGE
CASE 221A–06
ISSUE Y
NOTES:
1. DIMENSIONING AND TOLERANCING PER ANSI
Y14.5M, 1982.
SEATING
PLANE
–T–
2. CONTROLLING DIMENSION: INCH.
3. DIMENSION Z DEFINES A ZONE WHERE ALL
BODY AND LEAD IRREGULARITIES ARE
ALLOWED.
C
S
B
F
T
INCHES
MIN
MILLIMETERS
4
DIM
A
B
C
D
F
G
H
J
K
L
N
Q
R
S
MAX
0.620
0.405
0.190
0.035
0.147
0.105
0.155
0.025
0.562
0.060
0.210
0.120
0.110
0.055
0.255
0.050
–––
MIN
14.48
9.66
4.07
0.64
3.61
2.42
2.80
0.46
12.70
1.15
4.83
2.54
2.04
1.15
5.97
0.00
1.15
–––
MAX
15.75
10.28
4.82
0.88
3.73
2.66
3.93
0.64
14.27
1.52
5.33
3.04
2.79
1.39
6.47
1.27
–––
0.570
0.380
0.160
0.025
0.142
0.095
0.110
0.018
0.500
0.045
0.190
0.100
0.080
0.045
0.235
0.000
0.045
–––
A
K
Q
Z
1
2
3
U
H
L
R
J
V
T
U
V
G
D
Z
0.080
2.04
N
10
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
Motorola reserves the right to make changes without further notice to any products herein. Motorola makes no warranty, representation or guarantee regarding
the suitability of its products for any particular purpose, nor does Motorola assume any liability arising out of the application or use of any product or circuit, and
specificallydisclaims any and all liability, including without limitation consequential or incidental damages. “Typical” parameters which may be provided in Motorola
datasheetsand/orspecificationscananddovaryindifferentapplicationsandactualperformancemayvaryovertime. Alloperatingparameters,including“Typicals”
must be validated for each customer application by customer’s technical experts. Motorola does not convey any license under its patent rights nor the rights of
others. Motorola products are not designed, intended, or authorized for use as components in systems intended for surgical implant into the body, or other
applicationsintended to support or sustain life, or for any other application in which the failure of the Motorola product could create a situation where personal injury
ordeathmayoccur. ShouldBuyerpurchaseoruseMotorolaproductsforanysuchunintendedorunauthorizedapplication,BuyershallindemnifyandholdMotorola
and its officers, employees, subsidiaries, affiliates, and distributors harmless against all claims, costs, damages, and expenses, and reasonable attorney fees
arisingoutof,directlyorindirectly,anyclaimofpersonalinjuryordeathassociatedwithsuchunintendedorunauthorizeduse,evenifsuchclaimallegesthatMotorola
was negligent regarding the design or manufacture of the part. Motorola and
Opportunity/Affirmative Action Employer.
are registered trademarks of Motorola, Inc. Motorola, Inc. is an Equal
11
MOTOROLA ANALOG IC DEVICE DATA
MC78T00 Series
How to reach us:
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51 Ting Kok Road, Tai Po, N.T., Hong Kong. 852–26629298
MC78T00/D
◊
相关型号：
MC78T05CD2TG
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ONSEMI
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