LP2957 Datasheet, PDF (3/14 Pages) National Semiconductor (TI) – 5V Low-Dropout Regulator for P Applications

Electrical Characteristics (Continued)
Limits in standard typeface are
less otherwise specified: V_IN =
for T_J
6V, I_L
=
=
25˚C,
1 mA,
and limits in boldface type
C_L = 2.2 µF, V_SD = 3V.
apply
over
the
full
operating
temperature
range.
Un-
Symbol
Parameter
Conditions
Typical
LP2957AI
Min
Max
LP2957I
Min
Max
Units
e_n
Output Noise Voltage
C_L = 2.2 µF
500
(10 Hz to 100 kHz)
C_L = 33 µF
320
I_L = 100 mA
SHUTDOWN INPUT
µV
RMS
V_SD (ON)
Output Turn-On
Threshold Voltage
1.155 1.305 1.155 1.305
V
1.140 1.320 1.140 1.320
HYST
Hysteresis
6
mV
I_B
Input Bias
Current
V_IN(SD) = 0V to 5V
10
−30
30
−30
30
nA
−50
50
−50
50
DROPOUT DETECTION COMPARATOR
I_OH
Output “HIGH”
V_OH = 30V
0.01
1
Leakage
2
1
µA
2
V_OL
V_THR
(Max)
Output “LOW”
Voltage
Upper Threshold
Voltage
V_IN = 4V
I_O(COMP) = 400 µA
(Note 8)
150
250
250
mV
400
400
−240 −320 −150 −320 −150
mV
−380 −100 −380 −100
V_THR
(Min)
Lower Threshold
Voltage
(Note 8)
−350 −450 −230 −450 −230
mV
−640 −160 −640 −160
HYST
Hysteresis
(Note 8)
60
mV
Note 1: Absolute maximum ratings indicate limits beyond which damage to the component may occur. Electrical specifications do not apply when operating the de-
vice outside of its rated operating conditions.
Note 2: The maximum allowable power dissipation is a function of the maximum junction temperature, T _J(MAX), the junction-to-ambient thermal resistance, θ _JA,
and the ambient temperature, T_A. The maximum allowable power dissipation at any ambient temperature is calculated using:
Exceeding the maximum allowable power dissipation will result in excessive die temperature, and the regulator will go into thermal shutdown. The junction-to-ambient
thermal resistance of the TO-220 (without heatsink) is 60˚C/W and 73˚C/W for the TO-263. If the TO-263 package is used, the thermal resistance can be reduced
by increasing the P.C. board copper area thermally connected to the package: Using 0.5 Square inches of copper area, θ _JA is 50˚C/W, with 1 square inch of copper
area, θ_JA is 37˚C/W; and with 1.6 or more square inches of copper area, θ _JA is 32˚C/W. The junction-to-case thermal resistance is 3˚C/W. If an external heatsink is
used, the effective junction-to-ambient thermal resistance is the sum of the junction-to-case resistance (3˚C/W), the specified thermal resistance of the heatsink se-
lected, and the thermal resistance of the interface between the heatsink and the LP2957 (see Application Hints).
Note 3: Output voltage temperature coefficient is defined as the worst case voltage change divided by the total temperature range.
Note 4: Regulation is measured at constant junction temperature using low duty cycle pulse testing. Parts are tested separately for load regulation in the load ranges
0.1 mA–1 mA and 1 mA–250 mA. Changes in output voltage due to heating effects are covered by the thermal regulation specification.
Note 5: Dropout voltage is defined as the input to output voltage differential at which the output voltage drops 100 mV below the value measured with a 1V input
to output differential.
Note 6: Ground pin current is the regulator quiescent current. The total current drawn from the source is the sum of the load current plus the ground pin current.
Note 7: Thermal regulation is defined as the change in output voltage at a time T after a change in power dissipation is applied, excluding load or line regulation ef-
fects. Specifications are for a 200 mA load pulse at V_IN = 20V (3W pulse) for T = 10 ms.
Note 8: Voltages are referenced to the nominal regulated output voltage.
Note 9: When used in dual-supply systems where the regulator load is returned to a negative supply, the output voltage must be diode-clamped to ground.
3
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