1038fa, ELEKTRONIKA, Dane elementów elektronicznych
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LT1038
OBSOLETE PRODUCT
DATA SHEET FOR REFERENCE ONLY
Consult www.linear.com for possible alternate source.
10A Positive
Adjustable Voltage
Regulator
FEATURES
DESCRIPTIO
n
Guaranteed
0.8% Initial Tolerance
The LT
®
1038 is a three terminal regulator which is capable
of providing in excess of 10A output current over 1.2V to
32V range. The device is packaged in a standard T0-3
power package and is plug-in compatible with industry
standard adjustable regulators, such as the LM117 and
LM138. Also, the LT1038 is a functional replacement for
the LM396.
In addition to excellent load and line regulations, the
LT1038 is fully protected by current limiting, safe area
protection and thermal shutdown. New current limiting
circuitry allows transient load currents up to 24A to be
supplied for 500
n
Guaranteed
0.4% Load Regulation
n
Guaranteed
10A Output Current
n
100% Thermal Limit Burn-In
n
24A Transient Output Current
n
Standard Adjustable Pinout
n
Operates to 35V
APPLICATIO
U
n
System Power Supplies
n
High Power Linear Regulator
s without causing the regulator to cur-
rent limit and drop out of regulation during the transient.
On-chip trimming of initial reference voltage to
m
n
Battery Chargers
n
Power Driver
0.8%
combined with 0.4% load regulation minimize errors in all
high current applications. Further, the LT1038 is manufac-
tured with standard bipolar processing and has Linear
Technology’s high reliability.
±
n
Constant Current Regulator
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIO
N
S
5V, 10A Regulator
Load Regulation
0.2
V
IN
= 15V
V
OUT
= 10V
PRELOAD = 100mA
0.1
LT1038
5V
AT 10A
V
IN
³
8V
V
IN
V
OUT
0
121
½
I
OUT
= 6A
ADJ
+
1%
+
µ
F
10
µ
– 0.1
I
OUT
= 10A
365
½
1%
– 0.2
1038 TA01
– 0.3
– 0.4
–75
–50
–25
0
25 50
75 100 125
150
TEMPERATURE (
°
C)
1038 TA02
1
1
F
LT1038
ABSOLUTE AXI U RATI GS
PACKAGE/ORDER I FOR ATIO
U
W
U
(Note 1)
Power Dissipation ............................... Internally Limited
Input to Output Voltage Differential ......................... 35V
Operating Junction Temperature Range
LT1038M Control Circuitry ................ –55
BOTTOM VIEW
ORDER PART
NUMBER
V
IN
2
°
C to 150
°
C
1
LT1038MK
LT1038CK
LT1038M Power Transistor ............... –55
°
C to 200
°
C
CASE
IS OUTPUT
ADJ
LT1038C Control Circuitry ..................... 0
°
C to 125
°
C
K PACKAGE
2-LEAD TO-3 METAL CAN
LT1038C Power Transistor .................... 0
°
C to 175
°
C
T
JMAX
= 3
°
C,
q
JA
= 35
°
C/W
Storage Temperature Range ................. – 65
°
C to 150
°
C
OBSOLETE PACKAGE
Lead Temperature (Soldering, 10 sec) .................. 300
°
C
PRECO DITIO I G
100% Thermal Limit Burn-in
ELECTRICAL CHARACTERISTICS
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25
°
C. (Note 2)
LT1038M
LT1038C
SYMBOL PARAMETER
CONDITIONS
MIN
TYP
MAX
MIN
TYP
MAX
UNITS
V
REF
Reference Voltage
I
OUT
= 20mA, T
j
= 25
°
C
1.24
1.25
1.26
1.23
1.25
1.275
V
3V
£
(V
IN
– V
OUT
)
£
35V
l
1.22
1.25
1.285
1.22
1.25
1.285
V
20mA
£
I
OUT
£
10A, P
£
75W
D
V
OUT
Line Regulation
3V
£
(V
IN
– V
OUT
)
£
35V,
0.005
0.01
0.005
0.02
%/V
D
V
IN
I
OUT
= 20mA (Note 3)
l
0.02
0.03
0.02
0.03
%/V
D
V
OUT
Load Regulation
20mA
£
I
OUT
£
10A (Note 3)
D
I
OUT
3V
£
(V
IN
– V
OUT
)
£
35V
0.1
0.4
0.1
0.6
%
3V
£
(V
IN
– V
OUT
)
£
35V
l
0.3
0.8
0.3
1.0
%
Thermal Regulation
20ms Pulse
0.002
0.005
0.002
0.01
%/W
Ripple Rejection
V
OUT
= 10V, f = 120Hz
C
ADJ
= 0
m
F
l
60
60
dB
C
ADJ
= 10
m
F
l
60
75
60
75
dB
I
ADJ
Adjust Pin Current
l
50
100
50
100
m
A
D
I
ADJ
Adjust Pin Current Change 20mA
£
I
OUT
£
10A
3V
£
(V
IN
– V
OUT
)
£
35V
l
0.2
3
0.2
3
m
A
Minimum Load Current
(V
IN
– V
OUT
) = 35V
l
7
20
7
20
mA
(V
IN
– V
OUT
)
£
20V
l
10
10
mA
I
SC
Current Limit
(V
IN
– V
OUT
)
£
10V
DC
l
10
14
10
14
A
Transient (0.5ms)
14
22
12
22
A
(V
IN
– V
OUT
) = 30V, T
j
= 25
°
C
1
2
1
2
A
D
V
OUT
Temperature Stability
l
1
2
1
%
D
Temp
D
V
OUT
Long Term Stability
T
A
= 125
°
C, 1000 Hours
0.3
1
0.3
1
%
Time
e
n
RMS Output Noise
10Hz
£
£
10kHz
0.001
0.001
%
(% of V
OUT
)
q
JC
Thermal Resistance
Power Transistor
l
1
1
°
C/W
Junction to Case
Control Circuity
0.5
0.5
°
C/W
2
D
f
LT1038
ELECTRICAL CHARACTERISTICS
Note 1:
Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2:
Unless otherwise specified, these specifications apply:
V
IN
– V
OUT
= 5V and I
OUT
= 5A. These specifications are applicable for
power dissipations up to 75W. At input-output voltage differentials greater
than 10V, achievable output current and power dissipation decrease due to
protection circuitry.
Note 3:
See thermal regulation specifications for changes in output voltage
due to heating effects. Load and line regulation are measured at a constant
junction temperature by low duty cycle pulse testing.
TYPICAL PERFOR A CE CHARACTERISTICS
Dropout Voltage
Adjustment Current
Temperature Stability
4
D
V
OUT
= 100mV
65
1.27
60
1.26
55
3
I
OUT
= 10A
50
1.25
I
OUT
= 6A
45
2
I
OUT
= 2A
40
1.24
35
1
–75
–50
–25
0
25 50
75 100 125
150
30
–75
–50
–25
0
25 50
75 100 125
150
1.23
–50
–25
0
25
50
75
100
125
150
TEMPERATURE (
°
C)
TEMPERATURE (
°
C)
TEMPERATURE (
°
C)
1038 TA02
1038 G02
1038 G03
Output Impedance
Minimum Operating Current
Ripple Rejection
10
10
100
V
IN
= 15V
V
OUT
= 10V
I
OUT
= 1A
C
ADJ
= 10
µ
F
1
8
80
T
j
= 150
°
C
C
ADJ
= 0
µ
F
0.1
C
ADJ
= 0
µ
F
6
T
j
= 25
°
C
60
C
OUT
= 0
µ
F
0.01
C
ADJ
= 10
µ
F
4
T
j
= – 55
°
C
40
C
OUT
= 10
µ
F
0.001
2
20
V
IN
– V
OUT
= 5V
I
OUT
= 1A
f = 120Hz
T
j
= 25
°
0.0001
0
0
10
100
1k
10k
100k
1M
0
50
15
20
25
30 35
40
0
5
10
15
20
25
30
35
FREQUENCY (Hz)
INPUT-OUTPUT DIFFERENTIAL (V)
OUTPUT VOLTAGE (V)
1038 G04
1038 G05
1038 G06
3
C
LT1038
TYPICAL PERFOR A CE CHARACTERISTICS
Ripple Rejection
Ripple Rejection
Current Limit
100
80
32
V
IN
= 15V
V
OUT
= 10V
I
OUT
= 1A
PEAK CURRENT LIMIT
DC CURRENT LIMIT
T
CASE
= 25
°
C
PRELOAD = 0A
C
ADJ
= 10
µ
F
C
ADJ
= 10
µ
F
80
70
24
60
C
ADJ
= 0
µ
F
P
R
ELOAD = 10A
60
16
C
ADJ
= 0
µ
F
40
PRELOAD = 2A
8
50
V
IN
= 15V
V
OUT
= 10V
f = 120Hz
T
CASE
= 25
°
C
20
0
0
40
10
100
1k
10k
100k
1M
0.1
1
10
0
10
20
30
40
FREQUENCY (Hz)
OUTPUT CURRENT (A)
INPUT-OUTPUT DIFFERENTIAL (V)
1038 G07
1038 G08
1195 G20
Current Limit
Current Limit
Line Transient Response
28
V
IN
= 10V
V
OUT
= 5V
T
CASE
= 25
°
C
28
1.5
V
OUT
= 10V
I
OUT
= 100mA
T
j
= 25
PRELOAD CURRENT = 0A
T
CASE
= 25
24
24
°
1.0
0.5
°
C
C
L
= 1
µ
F; C
L
= 10
µ
F
20
20
0
PRELOAD = 10A
PRELOAD = 0A
V
IN
– V
OUT
= 10V
16
16
– 0.5
–1.0
12
12
V
IN
– V
OUT
= 15V
C
OUT
= 0A
C
ADJ
= 0A
–1.5
1.0
8
8
V
IN
– V
OUT
= 20V
4
4
V
IN
– V
OUT
= 30V
0.5
0
0
0
0.1
1
10
100
0.1
1
10
100
0
10
20
30
40
TIME (ms)
TIME (ms)
TIME (
µ
s)
LTXXX GXX
1038 G11
1038 G12
Load Transient Response
3
2
1
0
–1
–2
–3
6
4
2
0
C
PRELOAD = 200mA
°
C
L
= 0
µ
F; C
ADJ
= 0
µ
F
C
L
= 1
µ
F; C
ADJ
= 10
µ
F
0
10
20
30
40
TIME (
µ
s)
1038 G13
4
C
V
IN
= 15V
V
OUT
= 10V
T
CASE
= 25
LT1038
APPLICATIO S I FOR ATIO
General
The LT1038 develops a 1.25V reference voltage between
the output and the adjustment terminal (see Figure 1). By
placing a resistor, R1, between these two terminals, a
constant current is caused to flow through R1 and down
through R2 to set the overall output voltage. Normally this
current is the specified minimum load current of 10mA or
20mA. Because I
ADJ
is very small and constant when
compared with the current through R1, it represents a
small error and can usually be ignored.
F
shown in Figure 2, the regulator could be damaged or
destroyed if the input is accidentally shorted to ground or
crowbarred, due to the output capacitor discharging into
the output terminal of the regulator. To prevent this, a
diode, D1 as shown, is recommended to safely discharge
the capacitor.
m
Load Regulation
Because the LT1038 is a three-terminal device, it is not
possible to provide true remote load sensing. Load regu-
lation will be limited by the resistance of the wire connect-
ing the regulator to the load. The data sheet specification
for load regulation is measured at the bottom of the
package. Negative side sensing can be a true Kelvin
connection if the bottom of resistor R2 is returned to the
negative side of the load. Although it may not be immedi-
ately obvious, best load regulation is obtained when the
top of the resistor divider, R1, is connected directly to the
case, not to the load. This is illustrated in Figure 3. If R1
were connected to the load, the effective resistance be-
tween the regulator and the load would be:
F electrolytic
is recommended when the input filter capacitors are more
than 5 inches from the device. Improved ripple rejection
(80dB) can be accomplished by adding a 10
m
F tantalum or 25
m
F capacitor
from the ADJ pin to ground. Increasing the size of the
capacitor to 20
m
F will help ripple rejection at low output
voltage since the reactance of this capacitor should be
small compared to the voltage setting resistor, R2. For
improved AC transient response and to prevent the possi-
bility of oscillation due to unknown reactive load, a 1
m
F
capacitor is also recommended at the output. Because of
their low impedance at high frequencies, the best type of
capacitor to use is solid tantalum.
m
R
p
•
æ
ç
RR
R
21
ö
÷
R
p
= Parasitic Line Resistance
Protection Diodes
The LT1038 does not require a protection diode from the
adjustment terminal to the output (see Figure 2). Im-
proved internal circuitry eliminates the need for this diode
when the adjustment pin is bypassed with a capacitor to
improve ripple rejection.
per foot using 16 gauge wire.
This translates to 4mV/ft at 1A load current, so it is
important to keep the lead between the regulator and the
load as short as possible, and use large wire or PC board
traces.
W
D1
1N4002
R
p
PARASITIC
LINE
RESIS
TANCE
LT1038
LT1038
V
IN
V
IN
V
OUT
V
OUT
LT1038
V
IN
V
IN
V
OUT
ADJ
V
REF
V
IN
V
IN
V
OUT
+
V
OUT
ADJ
CONNECT
R1 TO CASE
R1
ADJ
C
OUT
100
µ
F
I
ADJ
50
R1
*
µ
A
R1
R
L
R2
R2
+
V
OUT
= V
REF
(
1 +
)
+ I
ADJ
R2
R2
R1
C
ADJ
10
µ
F
R2
*NOT NEEDED
1038 F01
CONNECT R2
TO LOAD
1038 F02
1038 F03
Figure 1. Basic Adjustable Regulator
Figure 2
Figure 3. Connections for
Best Load Regulation
5
If a very large output capacitor is used, such as a 100
Bypass Capacitors
Input bypassing using a 1
+
Connected as shown, R
p
is not multiplied by the divider
ratio. R
p
is about 0.004
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