LP2950
DEFINITIONS
Dropout Voltage – The input/output voltage differential
Output Noise Voltage – The rms ac voltage at the output,
with constant load and no input ripple, measured over a
specified frequency range.
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.
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.
Bias Current – Current which is used to operate the
regulator chip and is not delivered to the load.
Figure 1. Quiescent Current
Figure 2. Dropout Characteristics
10
6.0
LP2951C
T = 25°C
A
5.0
4.0
3.0
2.0
1.0
0
R = 50 k
L
1.0
0.1
R = 50 Ω
L
0.01
0.1
1.0
10
100
0
1.0
2.0
3.0
4.0
5.0
6.0
I , LOAD CURRENT (mA)
L
V , INPUT VOLTAGE (V)
in
Figure 3. Input Current
Figure 4. Output Voltage versus Temperature
250
5.00
4.99
4.98
4.97
4.96
4.95
200
150
100
50
0.1 mA Load Current
No Load
LP2951C
0
0
5.0
10
15
20
25
– 50
0
50
100
150
200
V , INPUT VOLTAGE (V)
in
T , AMBIENT TEMPERATURE (°C)
A
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