LM3420AM5-4.2 National Semiconductor, LM3420AM5-4.2 Datasheet - Page 10

• Manufacturer Part Number: LM3420AM5-4.2
• Description: IC CTRLR LIION BAT CHRG SOT23-5
• Manufacturer: National Semiconductor
• Type: Battery Chargerr

Specifications of LM3420AM5-4.2

• Function: Charge Management
• Battery Type: Lithium-Ion (Li-Ion)
• Operating Temperature: -40°C ~ 85°C
• Mounting Type: Surface Mount
• Package / Case: SC-74A, SOT-753
• Output Current: 15mA
• Output Voltage: 4.2V
• Operating Supply Voltage (max): 20V
• Operating Temp Range: -40C to 85C
• Package Type: SOT-23
• Mounting: Surface Mount
• Pin Count: 5
• Operating Temperature Classification: Industrial
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Other names: *LM3420AM5-4.2TR; LM3420AM5-4.2; LM3420AM5-4.2TR

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Five Lead Surface Mount Package Information
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.
The first letter “D” identifies the part as a Driver, the next two
numbers indicate the voltage, “02” for a 4.2V part, “07” for an
8.2V part, “03” for an 8.4V part, “04” for a 12.6V part, and
“05” for a 16.8V 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 quantity increments of 1000 on tape and reel (indi-
cated by the letters “M5” in the part number), or in quantity
increments of 3000 on tape and reel (indicated by the letters
“M5X” in the part number).
Product Description
The LM3420 is a shunt regulator specifically designed to be
the reference and control section in an overall feedback loop
of a Lithium-Ion battery charger. The regulated output volt-
age is sensed between the IN pin and GROUND pin of the
LM3420. If the voltage at the IN pin is less than the LM3420
regulating voltage (V
As the voltage at the IN pin approaches the V
the OUT 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 ser-
vos 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
REG
Voltage
12.6V
12.6V
12.6V
12.6V
16.8V
16.8V
16.8V
16.8V
4.2V
4.2V
4.2V
4.2V
8.2V
8.2V
8.2V
8.2V
8.4V
8.4V
8.4V
8.4V
voltage. In these instances, the maximum voltage
A (Prime)
A (Prime)
B (Standard)
B (Standard)
A (Prime)
A (Prime)
B (Standard)
B (Standard)
A (Prime)
A (Prime)
B (Standard)
B (Standard)
A (Prime)
A (Prime)
B (Standard)
B (Standard)
A (Prime)
A (Prime)
B (Standard)
B (Standard)
REG
Grade
), the OUT pin sources no current.
LM3420AM5-4.2
LM3420AM5X-4.2
LM3420M5-4.2
LM3420M5X-4.2
LM3420AM5-8.2
LM3420AM5X-8.2
LM3420M5-8.2
LM3420M5X-8.2
LM3420AM5-8.4
LM3420AM5X-8.4
LM3420M5-8.4
LM3420M5X-8.4
LM3420AM5-12.6
LM3420AM5X-12.6
LM3420M5-12.6
LM3420M5X-12.6
LM3420AM5-16.8
LM3420AM5X-16.8
LM3420M5-16.8
LM3420M5X-16.8
Information
REG
Order
FIGURE 1. SOT23-5 Marking
REG
voltage,
.
10
Package
Marking
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 (C
pin to the out pin of the LM3420. The capacitor values shown
in the schematics are adequate under most conditions, but
they can be increased or decreased depending on the de-
sired loop response. Applying a load pulse to the output of a
regulator circuit and observing the resultant output voltage
response is an 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;
D02A
D02A
D02B
D02B
D07A
D07A
D07B
D07B
D03A
D03A
D03B
D03B
D04A
D04A
D04B
D04B
D05A
D05A
D05B
D05B
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
1000 unit increments on tape and reel
3000 unit increments on tape and reel
C
) connected from the compensation
Supplied as