Datasheet LM3411AM5-5.0, LM3411AM5-3.3, LM3411M5X-5.0, LM3411M5X-3.3, LM3411AM5X-5.0 Datasheet (NSC)

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Page 1
LM3411 Precision Secondary Regulator/Driver
General Description
The LM3411isalowpowerfixed-voltage(3.3Vor5.0V)pre­cision shunt regulator designed specifically fordrivinganop­toisolator to provide feedback isolation in a switching regula­tor.
The LM3411 circuitry includes an internally compensated op amp, a bandgap reference, NPN output transistor, and volt­age setting resistors.
A trimmed precision bandgap reference with temperature drift curvature correction, provides a guaranteed 1%preci­sion over theoperatingtemperature 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 criti­cal applications.
Although its main application is to provide a precision output voltage (no trimming required) and maintain very good regu­lation 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
LM3411 Precision Secondary Regulator/Driver
December 1999
Typical Application and Functional Diagram
DS011987-1
Basic Isolated DC/DC Converter
DS011987-2
LM3411 Functional Diagram
SIMPLE SWITCHER™is a tradmark of National Semiconductor Corporation.
© 1999 National Semiconductor Corporation DS011987 www.national.com
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Connection Diagrams and Order Information
LM3411
5-Lead Small Outline Package (M5)
Actual Size
DS011987-4
Top View
DS011987-3
For Ordering Information
See
Figure 1
See NS Package Number MA05B
in this Data Sheet
*No internal connection, but should be soldered to PC board for best heat transfer.
Five Lead Surface Mount Package Marking and Order Information (SOT23-5)
The small SOT23-5 package allows only 4 alphanumeric characters to identify the product. The table below contains the field in­formation marked on the package.
Grade
3.3V A (Prime) LM3411AM5-3.3 D00A 1000 unit increments on tape and reel
3.3V A (Prime) LM3411AM5X-3.3 D00A 3000 unit increments on tape and reel
3.3V B (Standard) LM3411M5-3.3 D00B 1000 unit increments on tape and reel
3.3V B (Standard) LM3411M5X-3.3 D00B 3000 unit increments on tape and reel
5.0V A (Prime) LM3411AM5-5.0 D01A 1000 unit increments on tape and reel
5.0V A (Prime) LM3411AM5X-5.0 D01A 3000 unit increments on tape and reel
5.0V B (Standard) LM3411M5-5.0 D01B 1000 unit increments on tape and reel
5.0V B (Standard) LM3411M5X-5.0 D01B 3000 unit increments on tape and reel
The first letter “D” identifies the part as a Driver, the next two numbers indicate the voltage, “00” for 3.3V part and “01” for a 5V part. The fourth letter indicates the grade, “B” for standard grade, “A” for the prime grade.
The SOT23-5 surface mount package is only available on tape in quantities increments of 250 on tape and reel (indicated by the letters “M5” in the part number), or in quantities increments of 3000 on tape and reel (indicated by the letters “M5X” in the part number).
Order Information Package
Marking
FIGURE 1. SOT23-5 Marking and Order Information
Supplied as
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Page 3
Absolute Maximum Ratings (Note 1)
If Military/Aerospace specified devices are required, please contact the National Semiconductor Sales Office/ Distributors for availability and specifications.
Input Voltage V(IN) 20V Output Current 20 mA Junction Temperature 150˚C Storage Temperature −65˚C to +150˚C Lead Temperature
Vapor Phase (60 sec.) +215˚C Infrared (15 sec.) +220˚C
Power Dissipation (T
2) 300 mW
=
25˚C) (Note
A
ESD Susceptibility (Note 3)
Human Body Model 1500V
See AN-450 “Surface Mounting Methods and Their Effect on Product Reliability” for methods on soldering surface-mount devices.
Operating Ratings (Notes 1, 2)
Ambient Temperature Range −40˚C T Junction Temperature Range −40˚C T Output Current 15 mA
+85˚C
A
+125˚C
J
LM3411
LM3411-3.3 Electrical Characteristics
Specifications with standard type face are for T
ture Range. Unless otherwise specified, V(IN)=V
Symbol Parameter Conditions Typical LM3411A-3.3 LM3411-3.3 Units
V
REG
Regulation Voltage I
Regulation Voltage I
OUT
OUT
Tolerance
I
q
G
m
Quiescent Current I
OUT
Transconductance 20 µA I I
/V
OUT
REG
1mAI
A
V
Voltage Gain 1V V V
OUT
/V
REG
=
R
L
1V V
=
R
V
SAT
Output Saturation V(IN)=V (Note 7) I
I
L
Output Leakage V(IN)=V Current V
R
f
Internal Feedback 52 k
L
OUT
OUT
Resistor (Note 8) 65 65 k(max)
E
n
Output Noise I
OUT
Voltage
=
25˚C, and those with boldface type apply over full Operating Tempera-
J
REG,VOUT
=
1.5V.
(Note 4) Limit Limit (Limits)
(Note 5) (Note 5)
=
5 mA 3.3 V
3.317/3.333 3.333/3.366 V(max)
3.284/3.267 3.267/3.234 V(min)
=
5mA
=
5mA 85 µA
±
0.5/±1
±1/±
2
%
(max)
110/115 125/150 µA(max)
1 mA 3.3 mA/mV
OUT
1.5/0.75 1/0.50 mA/mV(min)
15 mA 6.0 mA/mV
OUT
3.3/2.0 2.5/1.7 mA/mV(min)
V
OUT
− 1.2V (−1.3) 1000 V/V
REG
140(Note 6) 550/250 450/200 V/V(min)
V
OUT
− 1.2V (−1.3) 3500 V/V
REG
2k 1500/900 1000/700 V/V(min)
+100 mV 1.0 V
REG
=
15 mA 1.2/1.3 1.2/1.3 V(max)
−100 mV 0.1 µA
REG
=
0V 0.5/1.0 0.5/1.0 µA(max)
39 39 k(min)
=
1 mA, 10 Hz f 10 kHz 50 µV
RMS
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LM3411-5.0 Electrical Characteristics
Specifications with standard type face are for T
LM3411
ture Range. Unless otherwise specified, V(IN)=V
Symbol Parameter Conditions Typical LM3411A-5.0 LM3411-5.0 Units
V
Regulation Voltage I
REG
Regulation Voltage I
OUT
OUT
Tolerance
I
q
G
m
Quiescent Current I
OUT
Transconductance 20 µA I I
/V
OUT
REG
1mAI
A
V
Voltage Gain 1V V V
OUT
/V
REG
=
R
L
1V V
=
R
V
SAT
Output Saturation V(IN)=V (Note 7) I
I
L
Output Leakage V(IN)=V Current V
R
f
Internal Feedback 94 k
L
OUT
OUT
Resistor (Note 8) 118 118 k(max)
E
n
Output Noise I
OUT
Voltage
Note 1: Absolute Maximum Ratings indicate limits beyond which damage to the device may occur. Operating Ratings indicate conditions for which the device is in­tended to be functional, but do not guarantee specific performance limits. For guaranteed specifications and test conditions, see the Electrical Characteristics. The guaranteed specifications apply only for the test conditions listed. Some performance characteristics may degrade when the device is not operated under the listed test conditions.
Note 2: The maximum power dissipation must be derated at elevated temperatures and is dictated by T bient thermal resistance), and T given in the Absolute Maximum Ratings, whichever is lower. The typical thermal resistance (θ for the M5 package.
Note 3: The human body model is a 100 pF capacitor discharged through a 1.5 kresistor into each pin. Note 4: Typical numbers are at 25˚C and represent the most likely parametric norm. Note 5: Limits are 100%production tested at 25˚C. Limits over the operating temperature range are guaranteed through correlation using Statistical Quality Control
(SQC) methods. The limits are used to calculate National’s Averaging Outgoing Level (AOQL).
Note 6: Actual test is done using equivalent current sink instead of a resistor load. Note 7: V Note 8: See Applications and Curves sections for information on this resistor.
SAT
=
V(IN) − V
(ambient temperature). The maximum allowable power dissipation at any temperature is (P
A
, when the voltage at the IN pin is forced 100 mV above the nominal regulating voltage (V
OUT
=
25˚C, and those with boldface type apply over full Operating Tempera-
J
REG,VOUT
=
1.5V.
(Note 4) Limit Limit (Limits)
(Note 5) (Note 5)
=
5mA 5 V
5.025/5.050 5.050/5.100 V(max)
4.975/4.950 4.950/4.900 V(min)
=
5mA
=
5mA 85 µA
±
0.5/±1
±1/±
2
110/115 125/150 µA(max)
1 mA 3.3 mA/mV
OUT
1.5/0.75 1.0/0.5 mA/mV(min)
15 mA 6.0 mA/mV
OUT
3.3/2.0 2.5/1.7 mA/mV(min)
V
OUT
− 1.2V (−1.3) 1000 V/V
REG
250(Note 6) 750/350 650/300 V/V(min)
V
OUT
− 1.2V (−1.3) 3500 V/V
REG
2k 1500/900 1000/700 V/V(min)
+100 mV 1.0 V
REG
=
15 mA 1.2/1.3 1.2/1.3 V(max)
−100 mV 0.1 µA
REG
=
0V 0.5/1.0 0.5/1.0 µA(max)
70 70 k(min)
=
1 mA, 10 Hz f 10 kHz 80 µV
(maximum junction temperature), θJA(junction to am-
Jmax
) when soldered to a printed circuit board is approximately 306˚C/W
JA
REG
Dmax
).
=
T
Jmax−TA
)/θJAor the number
%
(max)
RMS
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Typical Performance Characteristics
LM3411
Normalized Temperature Drift
Circuit Used for Bode Plots
Bold Plot
DS011987-30
DS011987-8
Quiescent Current
Bode Plot
Response Time for 3.3V Version
=
(C
0 pF)
C
DS011987-31
DS011987-33
Output Saturation Voltage (V)
SAT
Bode Plot
Response Time for 3.3V Version
=
(C
10 nF)
C
DS011987-32
DS011987-34
DS011987-44
Circuit Used for Response Time
DS011987-11
Response Time for 5V Version
=
(C
0 pF)
C
DS011987-35
DS011987-37
Response Time for 5V Version
=
(C
10 nF)
C
DS011987-36
DS011987-38
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Page 6
Typical Performance Characteristics (Continued)
LM3411
Tempco of Internal Feedback Resistor (Rf)
Regulation Voltage Change vs Output Current
Regulation Voltage vs Output Voltage and Load Resistance
Regulation Voltage vs Output Voltage and Load Resistance
DS011987-39
DS011987-42
DS011987-40
DS011987-41
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Product Description
The LM3411 is a shunt regulator specifically designed to be the reference and control section in an overall feedback loop of a regulated power supply. The regulated output voltage is sensed between the IN pin and GROUND pin of the LM3411. If the voltage at the IN pin is less than the LM3411 regulating voltage (V age at the IN pin approaches the V begins sourcing current. This current is then used to drive a
), the OUT pin sources no current. As the volt-
REG
voltage, the OUT pin
REG
feedback device, (opto-coupler) or a power device, (linear regulator, switching regulator, etc.) which servos the output voltage to be the same value as V
REG
.
In some applications, (even under normal operating condi­tions) the voltage on the IN pin can be forced above the V
voltage. In these instances, the maximum voltage ap-
REG
plied to the IN pin should not exceed 20V.In addition, an ex­ternal resistor may be required on the OUT pin to limit the maximum current to 20 mA.
Compensation
The inverting input of the error amplifier is brought out to al­low overall closed-loop compensation. In many of the appli­cations circuits shown here, compensation is provided by a single capacitor connected from the compensation pin to the out pin of the LM3411. The capacitor values shown in the schematics are adequate under most conditions, but they can be increased or decreased depending on the desired loop response. Applying a load pulse to the output of a regu­lator circuit and observing the resultant output voltage re­sponse is a easy method of determining the stability of the control loop. Analyzing more complex feedback loops re­quires additional information.
The formula for AC gain at a frequency (f) is as follows;
where Rf≈ 52 kΩ for the 3.3V part, and Rf≈ 94 kΩ for the 5V part.
The resistor (R on the die. Since this resistor value will affect the phase mar-
) in the formula is an internal resistor located
f
gin, the worst case maximum and minimum values are im­portant when analyzing closed loop stability. The minimum and maximum room temperature values of this resistor are specified in the Electrical Characteristics section of this data sheet, and a curve showing the temperature coefficient is shown in the curves section. In the applications shown here, the worst case phase margin occurs with minimum values of R
.
f
Test Circuit
The test circuit shown in and verify various LM3411 parameters. Test conditions are set by forcing the appropriate voltage at the V point and selecting the appropriate R the Electrical Characteristics section. Use a DVM at the “measure” test points to read the data.
Figure 2
can be used to measure
or I
L
OUT
as specified in
OUT
Set test
LM3411
FIGURE 2. LM3411 Test Circuit
DS011987-14
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Page 8
Applications Information
LM3411
DS011987-15
FIGURE 3. Isolated 250 mA Flyback Switching Regulator
FIGURE 4. Isolated 1.5A Flyback Switching Regulator Using a LM2577
The LM3411 regulator/driver provides the reference and feedback drive functions in a regulated power supply. It can also be used together with many different types of regula­tors, (both linear and switching) as well as other power semi­conductor devices to add precision and improve regulation specifications. Output voltage tolerances better than 0.5
%
are possible without using trim pots or precision resistors. One of the main applications of the LM3411 is to drive an
opto-isolator to provide feedback signal isolation in a switch­ing regulator circuit. For low current applications, (up to 250 mA) the circuit shown in
Figure 3
provides good regulation
and complete input/output electrical isolation. For an input voltage of 15V,this circuit can provide an output
of either 3.3V or 5V with a load current up to 250 mA with ex­cellent regulation characteristics. With the part values shown, this circuit operates at 80 kHz., and can be synchro­nized to a clock or an additional LM3578. (See LM1578 data sheet for additional information.)
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DS011987-16
An isolated DC/DC flyback converter capable of higher out­put current is shown in LM2577 SIMPLE SWITCHER
Figure 4
. This circuit utilizes the
voltage regulator for the Pulse Width Modulation (PWM), power switch and protection functions, while the LM3411 provides the voltage reference, gain and opto coupler drive functions. In this circuit, the ref­erence and error amplifier in the LM2577 are not used (note that the feedback pin is grounded). The gain is provided by the LM3411. Since the voltage reference is located on the secondary side of the transformer, this circuit provides very good regulation specifications.
The output of a switching regulator typically will contain a small ripple voltage at the switching frequency and may also contain voltage transients. These transient voltage spikes can be sensed by the LM3411 and could give an incorrect regulation voltage. An RC filter consisting of a 1resistor and a 100 nF capacitor will filter these transients and mini­mize this problem. The 1resistor should be located on the ground side of the LM3411, and the capacitor should be physically located near the package.
Page 9
Applications Information (Continued)
FIGURE 5. Precision 1A Buck Regulator
LM3411
DS011987-17
FIGURE 6. Negative Input, Negative or Positive Output Flyback Regulator
Improved output voltage tolerance and regulation specifica­tions are possible by combining the LM3411Awithone of the SIMPLE SWITCHER buck regulator IC’s, such as the LM2574, LM2575, or LM2576. The circuit shown in can provide a 5V,±0.5%Output (1%over the operating tem­perature range) without using any trim-pots or precision re­sistors. Typical line regulation numbers area1mVchange on the output for a 8V–18V change on the input, and load regulation of 1 mV with a load change from 100 mA–1A.
A DC-DC flyback converter that accepts a negative input voltage, and delivers either a positive or negative output is shown in
Figure 6
as the LM2574, LM2575, or LM2576, depending on how much output current is needed) operating in a flyback con­figuration. The LM3411 provides the reference and the re­quired level shifting circuitry needed to make the circuit work correctly.
A unique feature of this circuit is the ability to ground either the high or low side of the output, thus generating either a negative or a positive output voltage. Although no isolation is
. The circuit utilizes a buck regulator (such
Figure 5
DS011987-18
provided, with the addition of an opto-isolator and related components, this circuit could provide input/output isolation.
Combining a LM3411A-5.0with a 1A low dropout linear regu­lator results in a 5V ture range) regulator with excellent regulation specifications, with no trimming or 1%resistors needed.
An added benefit of this circuit (and also true of many of the other circuits shown here) is the high-side and low-side re­mote output voltage sensing feature. Sensing the output voltage at the load eliminates the voltage drops associated with wire resistance, thus providing near perfect load regula­tion.
A 5V, 1A regulator circuit featuring low dropout, very good regulation specifications, self protection features and allows output voltage sensing is shown in used is a LM2941 adjustable low dropout positive regulator, which also features an ON/OFF pin to provide a shutdown feature.
±
0.5%(1%over the operating tempera-
Figure 7
. The regulator
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Page 10
Applications Information (Continued)
LM3411
FIGURE 7. Precision 5V 1A Low Dropout Regulator
FIGURE 8. 3.3V 0.5A Low Dropout Regulator
Figure 8
The circuit in using the LM3411-3.3 and several discrete components.
shows a 3.3V low dropout regulator
DS011987-20
DS011987-19
This circuit is capable of excellent performance with both the dropout voltage and the ground pin current specifications im­proved over the LM2941/LM3411 circuit.
The standard LM317 three terminal adjustable regulator cir­cuit can greatly benefit by adding a LM3411. Performance is increased and features are added. The circuit shown in
ure 9
provides much improved line and load regulation,
Fig-
lower temperature drift, and full remote output voltage sens­ing on both the high and low side. In addition, a precise cur­rent limit or constant current feature is simple to add.
Current limit protection in most IC regulators is mainly to pro­tect the IC from gross over-current conditions which could otherwise fuse bonding wires or blow IC metalization, there­fore not much precision is needed for the actual current limit values. Current limit tolerances can sometimes vary from
±
10%to as high as +300%over manufacturing and tem­perature variations. Often critical circuitry requires a much tighter control over the amount of current the power supply can deliver. For example, a power supply may be needed that can deliver 100%of its design current, but can still limit the maximum current to 110%to protect critical circuitry from high current fault conditions.
The circuit in that is better than
Figure 9
can provide a current limit accuracy
±
4%, over all possible variations, in addi­tion to having excellent line, load and temperature specifications.
FIGURE 9. Precision Positive Voltage Regulator with Accurate Current Limit
Like the positive regulators, the performance of negative ad­justable regulators can also be improved by adding the LM3411. Output voltages of either 3.3V or 5V at currents up to 1.5A (3A when using a LM333) are possible. Adding two
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DS011987-21
resistors to the circuit in
Figure 10
limit feature as shown in
±
of
4%over manufacturing and temperature variations are
adds the precision current
Figure 11
. Current limit tolerances
possible with this circuit.
Page 11
Applications Information (Continued)
DS011987-22
FIGURE 10. Precision Negative Voltage Regulator
DS011987-23
FIGURE 11. Precision Negative Voltage
Regulator with Accurate Current Limit
Figure 12
Asimple 5V supply monitor circuit is shown in ing the LM3411’s voltage reference, op-amp (as a compara­tor) and output driver,this circuit provides a LED indication of the presence of the 5V supply.
. Us-
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.
DS011987-26
FIGURE 14. 250 mA Shunt Regulator
Perhaps one of the simplest applications for the LM3411 is the voltage detector circuit shown in
Figure 15
is low when the input voltage is less than V V(IN) pin rises above V internal NPN output resistor.
, the OUT pin is pulled high by the
REG
. The OUT pin
. When the
REG
LM3411
DS011987-24
FIGURE 12. 4.7V Power ON Detector with Hysteresis
±
The LM3411 initial room temperature tolerance is
±
0.5%for the “A” grade part. If a tighter tolerance is needed,
a trim scheme is shown in
±
mately
1%adjustment range of the regulation voltage
(V
).
REG
Figure 13
that provides approxi-
1%and
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.
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Page 12
Applications Information (Continued)
LM3411
Schematic Diagram
DS011987-28
FIGURE 16. Overvoltage Crowbar
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DS011987-29
Page 13
Physical Dimensions inches (millimeters) unless otherwise noted
LM3411 Precision Secondary Regulator/Driver
5-Lead Small Outline Package (M5)
Order Number LM3411M5-3.3, LM3411AM5-3.3,
LM3411M5-5.0 or LM3411AM5-5.0
NS Package Number MA05B
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National does not assume any responsibility for use of any circuitry described, no circuit patent licenses are implied and National reserves the right at any time without notice to change said circuitry and specifications.
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