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PDF LT1038 Data sheet ( Hoja de datos )
| Número de pieza | LT1038 | |
| Descripción | 10Amp Positive Adjustable Voltage Regulator | |
| Fabricantes | Linear Technology | |
| Logotipo |  |
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Hay una vista previa y un enlace de descarga de LT1038 (archivo pdf) en la parte inferior de esta página. Total 8 Páginas | ||
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OBSOLETE PRODUCT
DATA SHEET FOR REFERENCE ONLY
Consult www.linear.com for possible alternate source.
FEATURES
s Guaranteed 0.8% Initial Tolerance
s Guaranteed 0.4% Load Regulation
s Guaranteed 10A Output Current
s 100% Thermal Limit Burn-In
s 24A Transient Output Current
s Standard Adjustable Pinout
s Operates to 35V
U
APPLICATIO S
s System Power Supplies
s High Power Linear Regulator
s Battery Chargers
s Power Driver
s Constant Current Regulator
LT1038
10A Positive
Adjustable Voltage
Regulator
DESCRIPTIO
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 500µs without causing the regulator to cur-
rent limit and drop out of regulation during the transient.
On-chip trimming of initial reference voltage to ±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.
, LTC and LT are registered trademarks of Linear Technology Corporation.
TYPICAL APPLICATIONS
5V, 10A Regulator
VIN ≥ 8V
+
1µF
LT1038
VIN VOUT
ADJ
121Ω
1% +
365Ω
1%
5V
AT 10A
10µF
1038 TA01
Load Regulation
0.2
VIN = 15V
VOUT = 10V
0.1 PRELOAD = 100mA
0
IOUT = 6A
– 0.1 IOUT = 10A
– 0.2
– 0.3
– 0.4
– 75 – 50 – 25 0 25 50 75 100 125 150
TEMPERATURE (°C)
1038 TA02
1
1 page  
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 IADJ is very small and constant when
compared with the current through R1, it represents a
small error and can usually be ignored.
Bypass Capacitors
Input bypassing using a 1µF tantalum or 25µF 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 10µF capacitor
from the ADJ pin to ground. Increasing the size of the
capacitor to 20µF 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 1µF
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.
If a very large output capacitor is used, such as a 100µF
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.
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:
Rp
•
R2 + R1
R1
Rp = 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.
Connected as shown, Rp is not multiplied by the divider
ratio. Rp is about 0.004Ω 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.
LT1038
VIN VIN VOUT
VOUT
ADJ
IADJ
50µA
VREF R1
VOUT
=
VREF
(1
+
R2
R1
)
+
IADJ
R2
R2
1038 F01
D1
1N4002
LT1038
VIN VIN VOUT
+ VOUT
ADJ R1 *
COUT
100µF
CADJ +
10µF
R2 *NOT NEEDED
1038 F02
Rp
LT1038
PARASITIC
LINE RESISTANCE
VIN VIN
VOUT
ADJ CONNECT
R1 TO CASE
R1
R2
RL
CONNECT R2
TO LOAD
1038 F03
Figure 1. Basic Adjustable Regulator
Figure 2
Figure 3. Connections for
Best Load Regulation
5
5 Page | ||
| Páginas | Total 8 Páginas | |
| PDF Descargar | [ Datasheet LT1038.PDF ] | |
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