LP2950, LP2951, NCV2951
DEFINITIONS
Dropout Voltage
− The input/output voltage differential
at which the regulator output no longer maintains regulation
against further reductions in input voltage. Measured when
the output drops 100 mV below its nominal value (which is
measured at 1.0 V differential), dropout voltage is affected
by junction temperature, load current and minimum input
supply requirements.
Line Regulation
− The change in output voltage for a
change in input voltage. The measurement is made under
conditions of low dissipation or by using pulse techniques
such that average chip temperature is not significantly
affected.
Load Regulation
− The change in output voltage for a
change in load current at constant chip temperature.
Maximum Power Dissipation
− The maximum total
device dissipation for which the regulator will operate
within specifications.
Bias Current
− Current which is used to operate the
regulator chip and is not delivered to the load.
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LP2950/LP2951 BIAS CURRENT (mA)
Output Noise Voltage
− The RMS ac voltage at the
output, with constant load and no input ripple, measured
over a specified frequency range.
Leakage Current
− Current drawn through a bipolar
transistor collector−base junction, under a specified
collector voltage, when the transistor is “off”.
Upper Threshold Voltage
− Voltage applied to the
comparator input terminal, below the reference voltage
which is applied to the other comparator input terminal,
which causes the comparator output to change state from a
logic “0” to “1”.
Lower Threshold Voltage
− Voltage applied to the
comparator input terminal, below the reference voltage
which is applied to the other comparator input terminal,
which causes the comparator output to change state from a
logic “1” to “0”.
Hysteresis
− The difference between Lower Threshold
voltage and Upper Threshold voltage.
6.0
5.0
Vout , OUTPUT VOLTAGE (V)
LP2951C
T
A
= 25°C
R
L
= 50 kW
R
L
= 50
W
1.0
4.0
3.0
2.0
1.0
0
0.1
0.01
0.1
1.0
10
100
0
1.0
2.0
3.0
4.0
5.0
6.0
I
L
, LOAD CURRENT (mA)
V
in
, INPUT VOLTAGE (V)
Figure 2. Quiescent Current
Figure 3. 5.0 V Dropout Characteristics over
Load
5.00
Vout , OUTPUT VOLTAGE (V)
Vout , OUTPUT VOLTAGE (V)
4.99
4.98
4.97
4.96
LP2951C
4.95
− 50
6.0
LP2951C
5.0
4.0
3.0
2.0
25°C
1.0
125°C
0
0
50
100
150
200
0
1.0
T
A
, AMBIENT TEMPERATURE (°C)
−40°C
2.0
3.0
4.0
5.0
6.0
V
in
, INPUT VOLTAGE (V)
Figure 4. Output Voltage versus Temperature
Figure 5. 5.0 V Dropout Characteristics with
R
L
= 50
W
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