LM3411AM5-5.0/NOPB National Semiconductor, LM3411AM5-5.0/NOPB Datasheet - Page 8

• Manufacturer Part Number: LM3411AM5-5.0/NOPB
• Description: IC REG/DRIVER SECONDARY SOT23-5
• Manufacturer: National Semiconductor

Specifications of LM3411AM5-5.0/NOPB

• Reference Type: Shunt
• Voltage - Output: 5V
• Tolerance: ±0.5%
• Number Of Channels: 1
• Current - Cathode: 110µA
• Current - Output: 15mA
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SOT-23-5, SC-74A, SOT-25
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Voltage - Input: -
• Temperature Coefficient: -
• Current - Quiescent: -
• Other names: LM3411AM5-5.0/NOPBTR

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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
voltage at the IN pin approaches the V
pin begins sourcing current. This current is then used to
drive a 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
In some applications, (even under normal operating condi-
tions) the voltage on the IN pin can be forced above the
V
applied 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 ap-
plications 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
REG
voltage. In these instances, the maximum voltage
REG
), the OUT pin sources no current. As the
REG
REG
voltage, the OUT
.
FIGURE 2. LM3411 Test Circuit
8
control loop. Analyzing more complex feedback loops re-
quires additional information.
The formula for AC gain at a frequency (f) is as follows;
where R
part.
The resistor (R
on the die. Since this resistor value will affect the phase
margin, 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
Test Circuit
The test circuit shown in Figure 2 can be used to measure
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.
f
.
f
≈ 52 kΩ for the 3.3V part, and R
f
) in the formula is an internal resistor located
01198714
L
or I
f
OUT
≈ 94 kΩ for the 5V
as specified in
OUT
Set test