The ESR of a typical tantalum increases by approximately 2:1 as the temperature goes from 25°C down to

–40°C, so some guard band must be allowed.

8.2.2.2 ON/OFF Input Operation

The LP2985-N is shut off by driving the ON/OFF input low, and turned on by pulling the ON/OFF input high. If

this feature is not used, the ON/OFF input must be tied to VIN to keep the regulator output on at all times.

To provide proper operation, the signal source used to drive the ON/OFF input must be able to swing above

and below the specified turn-on/turn-off voltage thresholds listed in the Electrical Characteristics section under

VON/OFF. For the legacy chip, to prevent misoperation, the turn-on (and turn-off) voltage signals applied to the

ON/OFF input must have a slew rate that is ≥ 40 mV/µs. But for the new chip, there is no restriction on the slew

rate of the voltage signals applied to the ON/OFF pin.

8.2.3 Application Curves

at operating temperature TJ = 25°C, VIN = VOUT(NOM) + 1.0 V or 2.5 V (whichever is greater), IOUT = 1 mA,

ON/OFF pin tied to VIN, CIN = 1.0 µF, and COUT = 4.7 µF (unless otherwise noted)

Figure 8-3. Short-Circuit Current for Legacy Chip

at VIN = 6 V

200

s/div

0

200

400

600

800

1000

-6

-600

-5

0

-4

600

-3

1200

-2

1800

-1

2400

0

3000

1

3600

2

4200

3

4800

4

5400

5

6000

VIN = 6 V

Cbyp = 10 nF

VO = 3.3 V

VO

I SC

VIN = 6 V

Figure 8-4. Short-Circuit Current for New Chip at

VIN = 6 V

Figure 8-5. Short-Circuit Current for Legacy Chip

at VIN = 16 V

200

s/div

0

200

400

600

800

1000

-6

-600

-5

0

-4

600

-3

1200

-2

1800

-1

2400

0

3000

1

3600

2

4200

3

4800

4

5400

5

6000

VIN = 16 V

Cbyp = 10 nF

VO = 3.3 V

VO

I SC

Figure 8-6. Short-Circuit Current for New Chip at

VIN = 16 V

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LP2985-N

SNVS018Z – MARCH 2000 – REVISED MAY 2023

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