LP2951ACM-3.3 National Semiconductor, LP2951ACM-3.3 Datasheet - Page 16

• Manufacturer Part Number: LP2951ACM-3.3
• Description: Linear Voltage Regulator IC
• Manufacturer: National Semiconductor

Specifications of LP2951ACM-3.3

• Dropout Voltage Vdo: 380mV
• No. Of Pins: 8
• Output Current: 0.1A
• Peak Reflow Compatible (260 C): No
• Output Voltage: 3.3V
• Output Voltage Max: 3.3V
• Supply Voltage Max: 30V
• Leaded Process Compatible: No
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

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Application Hints
*See Application Hints
**Drive with TTL-high to shut down. Ground or leave open if shutdown
feature is not to be used.
Note: Pins 2 and 6 are left open.
Typical Applications
300mA Regulator with 0.75V Dropout
FIGURE 2. Adjustable Regulator
(Continued)
1A Regulator with 1.2V Dropout
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*Minimum input-output voltage ranges from 40mV to 400mV, depending on
load current. Current limit is typically 160mA.
REDUCING OUTPUT NOISE
In reference applications it may be advantageous to reduce
the AC noise present at the output. One method is to reduce
the regulator bandwidth by increasing the size of the output
capacitor. This is the only way noise can be reduced on the
3 lead LP2950 but is relatively inefficient, as increasing the
capacitor from 1µF to 220µF only decreases the noise from
430µV to 160µV rms for a 100kHz bandwidth at 5V output.
Noise can be reduced fourfold by a bypass capacitor across
R
Pick
or about 0.01µF. When doing this, the output capacitor must
be increased to 3.3µF to maintain stability. These changes
reduce the output noise from 430µV to 100µV rms for a
100kHz bandwidth at 5V output. With the bypass capacitor
added, noise no longer scales with output voltage so that
improvements are more dramatic at higher output voltages.
1
, since it reduces the high frequency gain from 4 to unity.
Wide Input Voltage Range Current Limiter
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