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.
*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
3.3VA (Prime)LM3411AM5-3.3D00A1000 unit increments on tape and reel
3.3VA (Prime)LM3411AM5X-3.3D00A3000 unit increments on tape and reel
3.3VB (Standard)LM3411M5-3.3D00B1000 unit increments on tape and reel
3.3VB (Standard)LM3411M5X-3.3D00B3000 unit increments on tape and reel
5.0VA (Prime)LM3411AM5-5.0D01A1000 unit increments on tape and reel
5.0VA (Prime)LM3411AM5X-5.0D01A3000 unit increments on tape and reel
5.0VB (Standard)LM3411M5-5.0D01B1000 unit increments on tape and reel
5.0VB (Standard)LM3411M5X-5.0D01B3000 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 InformationPackage
Marking
FIGURE 1. SOT23-5 Marking and Order Information
Supplied as
www.national.com2
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 Current20 mA
Junction Temperature150˚C
Storage Temperature−65˚C to +150˚C
Lead Temperature
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 kΩ resistor 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)LimitLimit(Limits)
(Note 5)(Note 5)
=
5mA5V
5.025/5.0505.050/5.100V(max)
4.975/4.9504.950/4.900V(min)
=
5mA
=
5mA85µA
±
0.5/±1
±1/±
2
110/115125/150µA(max)
≤ 1 mA3.3mA/mV
OUT
1.5/0.751.0/0.5mA/mV(min)
≤ 15 mA6.0mA/mV
OUT
3.3/2.02.5/1.7mA/mV(min)
≤ V
OUT
− 1.2V (−1.3)1000V/V
REG
250Ω (Note 6)750/350650/300V/V(min)
≤ V
OUT
− 1.2V (−1.3)3500V/V
REG
2kΩ1500/9001000/700V/V(min)
+100 mV1.0V
REG
=
15 mA1.2/1.31.2/1.3V(max)
−100 mV0.1µA
REG
=
0V0.5/1.00.5/1.0µA(max)
7070kΩ(min)
=
1 mA, 10 Hz ≤ f ≤ 10 kHz80µV
(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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