LP2951ACD-3.0G ON Semiconductor, LP2951ACD-3.0G Datasheet - Page 9

• Manufacturer Part Number: LP2951ACD-3.0G
• Description: IC REG LDO 100MA 3V 8-SOIC
• Manufacturer: ON Semiconductor

Specifications of LP2951ACD-3.0G

• Regulator Topology: Positive Fixed
• Voltage - Output: 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 V
• Output Type: Fixed
• Dropout Voltage (max): 0.08 V at 100 uA
• Output Current: 0.1 A
• Line Regulation: 0.1 %
• Load Regulation: 0.1 %
• Voltage Regulation Accuracy: 0.5 %
• Maximum Operating Temperature: + 125 C
• Mounting Style: SMD/SMT
• Minimum Operating Temperature: - 40 C
• Reference Voltage: 1.25 V
• Primary Input Voltage: 30V
• Output Voltage Fixed: 3V
• Dropout Voltage Vdo: 350mV
• No. Of Pins: 8
• Operating Temperature Range: -40°C To +125°C
• Termination Type: 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

Introduction
internal current limiting and thermal shutdown making them
user−friendly. Typical application circuits for the LP2950
and LP2951 are shown in Figures 20 through 28.
require a 1.0 mF (or greater) capacitance between the
LP2950/LP2951 output terminal and ground for stability.
Most types of aluminum, tantalum or multilayer ceramic
will perform adequately. Solid tantalums or appropriate
multilayer ceramic capacitors are recommended for
operation below 25°C.
is required for output stability. The capacitor can be reduced
to 0.33 mF for currents less than 10 mA, or 0.1 mF for currents
below 1.0 mA. Using the 8 pin versions at voltages less than
5.0 V operates the error amplifier at lower values of gain, so
that more output capacitance is needed for stability. For the
worst case operating condition of a 100 mA load at 1.23 V
output (output Pin 1 connected to the feedback Pin 7) a
minimum capacitance of 3.3 mF is recommended.
operated with no output load. When setting the output
voltage of the LP2951 with external resistors, the resistance
values should be chosen to draw a minimum of 1.0 mA.
LP2950/LP2951 input to ground if more than 4 inches of
wire connects the input to either a battery or power supply
filter capacitor.
create a pole, causing instability if high value external
resistors are used to set the output voltage. Adding a 100 pF
capacitor between the Output Pin 1 and the Feedback Pin 7
and increasing the output filter capacitor to at least 3.3 mF
will stabilize the feedback loop.
Error Detection Comparator
the LP2951 output voltage falls more than approximately
5.0% out of regulation. This value is the comparator’s
designed−in offset voltage of 60 mV divided by the 1.235 V
internal reference. As shown in the representative block
diagram. This trip level remains 5.0% below normal
regardless of the value of regulated output voltage. For
example, the error flag trip level is 4.75 V for a normal 5.0 V
regulated output, or 9.50 V for a 10 V output voltage.
signal and the regulated output voltage as the input voltage
The LP2950/LP2951 regulators are designed with
These regulators are not internally compensated and thus
At lower values of output current, less output capacitance
The LP2950 will remain stable and in regulation when
A bypass capacitor is recommended across the
Input capacitance at the LP2951 Feedback Pin 7 can
The comparator switches to a positive logic low whenever
Figure 2 is a timing diagram which shows the ERROR
APPLICATIONS INFORMATION
http://onsemi.com
9
to the LP2951 is ramped up and down. The ERROR signal
becomes valid (low) at about 1.3 V input. It goes high when
the input reaches about 5.0 V (V
Since the LP2951’s dropout voltage is dependent upon the
load current (refer to the curve in the Typical Performance
Characteristics), the input voltage trip point will vary with
load current. The output voltage trip point does not vary
with load.
requires an external pullup resistor. This resistor may be
returned to the output or some other voltage within the
system. The resistance value should be chosen to be
consistent with the 400 mA sink capability of the error
comparator. A value between 100 k and 1.0 MW is
suggested. No pullup resistance is required if this output is
unused.
comparator output will go high if it has been pulled up to an
external supply. To avoid this invalid response, the error
comparator output should be pulled up to V
Figure 18).
Programming the Output Voltage (LP2951)
fixed output voltage using its internal voltage divider by
tying Pin 1 (output) to Pin 2 (sense) and Pin 7 (feedback) to
Pin 6 (5.0 V tap). Alternatively, it may be programmed for
any output voltage between its 1.235 reference voltage and
its 30 V maximum rating. An external pair of resistors is
required, as shown in Figure 19.
ERROR
Voltage
Voltage
Output
The error comparator output is an open collector which
When operated in the shutdown mode, the error
The LP2951CX may be pin−strapped for the nominal
Input
Valid
Not
1.3 V
Figure 18. ERROR Output Timing
4.75 V
4.75 V + V
dropout
5.0 V
4.70 V + V
out
4.70 V
exceeds about 4.75 V).
1.3 V
dropout
Not
Valid
Pullup
to V
out
Pullup
to Ext
out
(see