Limits in standard typeface are for T

less otherwise specified: V

Symbol

Parameter

Conditions

Typical

LP2957AI

LP2957I

Units

Min

Max

Min

Max

e

n

Output Noise Voltage

C

500

µV

RMS

(10 Hz to 100 kHz)

I

C

320

SHUTDOWN INPUT

V

Output Turn-On

1.155

1.305

1.155

1.305

V

Threshold Voltage

1.140

1.320

1.140

1.320

HYST

Hysteresis

6

mV

I

B

Input Bias

V

10

−30

30

−30

30

nA

Current

−50

50

−50

50

DROPOUT DETECTION COMPARATOR

I

OH

Output “HIGH”

V

0.01

1

1

µA

Leakage

22

V

OL

Output “LOW”

V

150

250

250

mV

Voltage

I

400

400

V

THR

Upper Threshold

(Note 8)

−240

−320

−150

−320

−150

mV

(Max)

Voltage

−380

−100

−380

−100

V

THR

Lower Threshold

(Note 8)

−350

−450

−230

−450

−230

mV

(Min)

Voltage

−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.

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,

area,

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-

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.

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