LP2980AIM5-3.3 National Semiconductor, LP2980AIM5-3.3 Datasheet - Page 16

• Manufacturer Part Number: LP2980AIM5-3.3
• Description: V REG LDO +3.3V, SMD, 2980, SOT235
• Manufacturer: National Semiconductor

Specifications of LP2980AIM5-3.3

• Voltage Regulator Type: Positive Fixed LDO
• Voltage, Input Max: 16V
• Voltage, Output Max: 3.3V
• Current, Output Max: 0.05A
• Voltage, Dropout: 0.12V
• Accuracy, Percentage: 0.5%
• Outputs, No. Of: 1
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant

Typical Applications
(Continued)
01207853
FIGURE 7. 5V to 3.3V
@
3A Converter
With limited input voltage range, the LP2980 can control a 3.3V, 3A regulator with the use of a high current-gain external PNP
pass transistorias shown in . If the regulator is to be loaded with the full 3A, heat sinking will be required on the pass transistor
to keep it within its rated temperature range. Refer to the Heatsink Thermal Resistance Requirements, below. For best load
regulation at the high load current, the LP2980 output voltage connection should be made as close to the load as possible.
Although this regulator can handle a much higher load current than can the LP2980 alone, it can be shut down in the same
manner as the LP2980. When the ON/OFF control is brought low, the converter will be in shutdown, and will draw less than 1 µA
from the source.
Notes:
A. Drive this input with a logic signal (see Application Hints). If the shutdown function is not to be used, tie the ON/OFF pin directly
to the V
pin.
IN
B. Capacitor is required for regulator stability. Minimum size is shown, and may be increased without limit.
C. Increasing the output capacitance improves transient response and increases phase margin.
D. A heatsink may be required for this transistor. The maximum allowable value for thermal resistance of the heatsink is
dependent on ambient temperature and load current (see curves in ). Once the value is obtained from the graph, a heatsink must
be selected which has a thermal resistance equal to or lower than this value. If the value is above 60˚C/W, no heatsink is required
(the TO-220 package alone will safely dissipate this).
For these curves, a maximum junction temperature of 150˚C is assumed for the pass transistor. The case-to-heatsink attachment
thermal resistance is assumed to be 1.5˚C/W. All calculations are for 5.5V input voltage (which is worst-case for power
dissipation).
01207854
FIGURE 8. Heatsink Thermal Resistance Requirements for
Figure 7
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