LT1460JCS3 データシートの表示（PDF） - Linear Technology

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LT1460JCS3

Family of Micropower Series References in SOT-23

Linear Technology 

LT1460S3 (SOT-23)

APPLICATIONS INFORMATION

Hysteresis

Hysteresis data shown in Figure 5 and Figure 6 represents

the worst-case data taken on parts from 0°C to 70°C and

from – 40°C to 85°C. The output is capable of dissipating

relatively high power, i.e., for the LT1460S3-2.5, PD =

17.5V • 20mA = 350mW. The thermal resistance of the

SOT-23 package is 325°C/W and this dissipation causes

a 114°C internal rise producing a junction temperature of

TJ = 25°C + 114°C = 139°C. This elevated temperature will

cause the output to shift due to thermal hysteresis. For

highest performance in precision applications, do not

let the LT1460S3’s junction temperature exceed 85°C.

18

WORST-CASE HYSTERESIS

16 ON 40 UNITS

14

12

10

70°C TO 25°C

0°C TO 25°C

8

6

4

2

0

–240 –200 –160 –120 – 80 –40 0 40 80 120 160 200 240

HYSTERESIS (ppm)

1460S3 F06

Figure 6. 0°C to 70°C Hysteresis

9

WORST-CASE HYSTERESIS

8 ON 34 UNITS

7

85°C TO 25°C

–40°C TO 25°C

6

5

4

3

2

1

0

–600 –500 –400 –300 –200 –100 0 100 200 300 400 500 600

HYSTERESIS (ppm)

1460S3 F07

Figure 7. – 40°C to 85°C Hysteresis

Fast Turn-On

It is recommended to add a 0.1µF or larger bypass

capacitor to the input pin of the LT1460S3s. Although this

can help stability with large load currents, another reason

is for proper start-up. The LT1460S3 can start in 10µs, but

it is important to limit the dv/dt of the input. Under light

load conditions and with a very fast input, internal nodes

overslew and this requires finite recovery time. Figure 8

shows the result of no bypass capacitance on the input and

no output load on the LT1460S3-5. In this case the supply

dv/dt is 7.5V in 30ns which causes internal overslew, and

the output does not bias to 5V until 40µs after turn-on.

Although 40µs is a typical turn-on time, it can be much

longer. Figure 9 shows the effect of a 0.1µF bypass

capacitor which limits the input dv/dt to approximately

7.5V in 20µs. The part always starts quickly.

7.5V

VIN

0V

VOUT

0V

20µs/DIV

Figure 8. CIN = 0µF

1460S3 F08

7.5V

VIN

0V

VOUT

20µs/DIV

Figure 9. CIN = 0.1µF

1460S3 F08

9

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