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PDF LM3411M5-3.3 Data sheet ( Hoja de datos )
| Número de pieza | LM3411M5-3.3 | |
| Descripción | Precision Secondary Regulator/Driver | |
| Fabricantes | National Semiconductor | |
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December 1999
LM3411
Precision Secondary Regulator/Driver
General Description
The LM3411 is a low power fixed-voltage (3.3V or 5.0V) pre-
cision shunt regulator designed specifically for driving an op-
toisolator to provide feedback isolation in a switching regula-
tor.
The LM3411 circuitry includes an internally compensated op
amp, a bandgap reference, NPN output transistor, and volt-
age setting resistors.
A trimmed precision bandgap reference with temperature
drift curvature correction, provides a guaranteed 1% preci-
sion over the operating temperature range (A grade version).
The amplifier’s inverting input is externally accessible for
loop frequency compensation when used as part of a larger
servo system. The output is an open-emitter NPN transistor
capable of driving up to 15 mA of load current.
Because of its small die size, the LM3411 has been made
available in the sub-miniature 5-lead SOT23-5 surface
mount package. This package is ideal for use in space criti-
cal applications.
Although its main application is to provide a precision output
voltage (no trimming required) and maintain very good regu-
lation in isolated DC/DC converters, it can also be used with
other types of voltage regulators or power semiconductors to
provide a precision output voltage without precision resistors
or trimming.
Features
n Fixed voltages of 3.3V and 5.0V with initial tolerance of
±1% for standard grade and ±0.5% for A grade
n Custom voltages available (3V–17V)
n Wide output current range, 20 µA–15 mA
n Low temperature coefficient
n Available in 5-lead SOT23-5 surface mount package
(tape and reel)
Applications
n Secondary controller for isolated DC/DC PWM switching
regulators systems
n Use with LDO regulator for high-precision fixed output
regulators
n Precision monitoring applications
n Use with many types of regulators to increase precision
and improve performance
Typical Application and Functional Diagram
Basic Isolated DC/DC Converter
DS011987-1
DS011987-2
LM3411 Functional Diagram
SIMPLE SWITCHER™ is a tradmark of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation DS011987
www.national.com
1 page  
Typical Performance Characteristics
Normalized
Temperature Drift
Quiescent Current
Output Saturation
Voltage (V)SAT
DS011987-30
Circuit Used for Bode Plots
Bode Plot
DS011987-31
Bode Plot
DS011987-32
Bold Plot
DS011987-8
Response Time
for 3.3V Version
(CC = 0 pF)
DS011987-33
Response Time
for 3.3V Version
(CC = 10 nF)
DS011987-34
DS011987-44
Circuit Used for Response Time
Response Time
for 5V Version
(CC = 0 pF)
DS011987-35
Response Time
for 5V Version
(CC = 10 nF)
DS011987-36
DS011987-11
DS011987-37
5
DS011987-38
www.national.com
5 Page 
Applications Information (Continued)
DS011987-22
FIGURE 10. Precision Negative Voltage Regulator
DS011987-25
FIGURE 13. ±50 mV External Trim
The LM3411 is guaranteed to drive a 15 mA load, but if more
current is needed, a NPN boost transistor can be added. The
circuit shown in Figure 14 is a shunt regulator capable of pro-
viding excellent regulation over a very wide range of current.
DS011987-23
FIGURE 11. Precision Negative Voltage
Regulator with Accurate Current Limit
A simple 5V supply monitor circuit is shown in Figure 12. Us-
ing the LM3411’s voltage reference, op-amp (as a compara-
tor) and output driver, this circuit provides a LED indication of
the presence of the 5V supply.
DS011987-26
FIGURE 14. 250 mA Shunt Regulator
Perhaps one of the simplest applications for the LM3411 is
the voltage detector circuit shown in Figure 15 . The OUT pin
is low when the input voltage is less than VREG. When the
V(IN) pin rises above VREG, the OUT pin is pulled high by the
internal NPN output resistor.
DS011987-24
FIGURE 12. 4.7V Power ON Detector with Hysteresis
The LM3411 initial room temperature tolerance is ±1% and
±0.5% for the “A” grade part. If a tighter tolerance is needed,
a trim scheme is shown in Figure 13 that provides approxi-
mately ±1% adjustment range of the regulation voltage
(VREG).
DS011987-27
FIGURE 15. Voltage Detector
Also an overvoltage detector, the crowbar circuit shown in
Figure 16 is normally located at the output of a power supply
to protect the load from an overvoltage condition should the
power supply fail with an input/output short.
11 www.national.com
11 Page | ||
| Páginas | Total 13 Páginas | |
| PDF Descargar | [ Datasheet LM3411M5-3.3.PDF ] | |
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