LP2951CD-3.3G ON Semiconductor, LP2951CD-3.3G Datasheet - Page 10

• Manufacturer Part Number: LP2951CD-3.3G
• Description: IC REG LDO 100MA 3.3V 8-SOIC
• Manufacturer: ON Semiconductor

Specifications of LP2951CD-3.3G

• Regulator Topology: Positive Fixed
• Voltage - Output: 3.3V
• Voltage - Input: Up to 30V
• Voltage - Dropout (typical): 0.35V @ 100mA
• Number Of Regulators: 1
• Current - Output: 100mA
• Operating Temperature: -40°C ~ 125°C
• Mounting Type: Surface Mount
• Package / Case: 8-SOIC (3.9mm Width)
• Number Of Outputs: 1
• Polarity: Positive
• Input Voltage Max: 30 V
• Output Voltage: 3.3 V
• Output Type: Fixed
• Dropout Voltage (max): 0.08 V at 100 uA
• Output Current: 100 mA
• Line Regulation: 0.2 %
• Load Regulation: 0.2 %
• Voltage Regulation Accuracy: 1 %
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Reference Voltage: 1.26 V
• Primary Input Voltage: 30V
• Output Voltage Fixed: 3.3V
• Dropout Voltage Vdo: 350mV
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +125°C
• Filter Terminals: SMD
• Rohs Compliant: Yes
• Lead Free Status / RoHS Status: Lead free / RoHS Compliant
• Current - Limit (min): -
• Lead Free Status / Rohs Status: Lead free / RoHS Compliant

where V
is the feedback pin bias current, nominally − 20 nA. The
minimum recommended load current of 1.0 mA forces an
upper limit of 1.2 MW on the value of R2, if the regulator
must work with no load. I
in V
adjusting R1. For better accuracy, choosing R2 = 100 k
reduces this error to 0.17% while increasing the resistor
program current to 12 mA. Since the LP2951 typically draws
75 mA at no load with Pin 2 open circuited, the extra 12 mA
of current drawn is often a worthwhile tradeoff for
eliminating the need to set output voltage in test.
Output Noise
present at the output. Reducing the regulator bandwidth by
increasing the size of the output capacitor is the only method
Shutdown
The complete equation for the output voltage is:
In many applications it is desirable to reduce the noise
Output
Error
Input
out
which may be eliminated at room temperature by
ref
V out + V
is the nominal 1.235 V reference voltage and I
100 k
Figure 19. Adjustable Regulator
5
3
Error
SD
GND FB
4
V
ref
V
in
in
8
V
(
SNS
V
1 ) R1 R2
O
FB
out
7
T
will produce a 2% typical error
2
6
1
NC
NC
R1
)
) I
R
FB
2
0.01 mF
R1
V
1.23 to 30 V
3.3 mF
out
http://onsemi.com
FB
10
for reducing noise on the 3 lead LP2950. However,
increasing the capacitor from 1.0 mF to 220 mF only
decreases the noise from 430 mV to 160 mVrms for a 100 kHz
bandwidth at the 5.0 V output.
across R1, since it reduces the high frequency gain from 4
to unity. Pick
or about 0.01 mF. When doing this, the output capacitor must
be increased to 3.3 mF to maintain stability. These changes
reduce the output noise from 430 mV to 126 mVrms for a
100 kHz bandwidth at 5.0 V output. With bypass
capacitor added, noise no longer scales with output voltage
so that improvements are more dramatic at higher output
voltages.
Unregulated
Noise can be reduced fourfold by a bypass capacitor
Shutdown
Output
Figure 20. 1.0 A Regulator with 1.2 V Dropout
Input
Input
Error
1.0 mF
C
5
3
Bypass
Error
SD
LP2951CN
10 k
GND FB
4
V
in
8
[
V
SNS
V
O
out
2pR1 x 200 Hz
7
T
1.0 M
2
6
1
0.002 mF
0.01 mF
1
2.0 k
MTB23P06E
220 mF
V
5.0 V ±1.0%
0 to 1.0 A
out