LT6660

9

6660fa

HYSTERESIS (ppm)

–240

–160

–80

0

8

70

°C TO 25°C

0

°C TO 25°C

10

12

6660 F06

6

4

80

160

–200

–120

–40

40

120

200

2

0

18

16

14

240

WORST-CASE HYSTERESIS

ON 40 UNITS

HYSTERESIS (ppm)

–600

–400

–200

0

4

85

°C TO 25°C

–40

°C TO 25°C

5

6

6660 F07

3

2

200

400

–500

–300

–100

100

300

500

1

0

9

8

7

600

WORST-CASE HYSTERESIS

ON 34 UNITS

Figure 6. 0°C to 70°C Hysteresis

Figure 7. –40°C to 85°C Hysteresis

Figure 5. Typical Long-Term Drift

HOURS

–150

–50

50

150

–100

0

100

200

400

600

800

6660 F05

1000

100

0

300

500

700

900

APPLICATIO S I FOR ATIO

Table 1 gives the maximum output capacitance for vari-

ous load currents and output voltages to avoid instability.

Load capacitors with low ESR (effective series resistance)

cause more ringing than capacitors with higher ESR such

as polarized aluminum or tantalum capacitors.

Table 1. Maximum Output Capacitance

VOLTAGE

OPTION

2.5V

>10µF

>10µF

2µF

0.68µF

3V

>10µF

>10µF

2µF

0.68µF

3.3V

>10µF

>10µF

1µF

0.68µF

5V

>10µF

>10µF

1µF

0.68µF

10V

>10µF

1µF

0.15µF

0.1µF

Long-Term Drift

Long-termdriftcannotbeextrapolatedfromaccelerated

high temperature testing. This erroneous technique

gives drift numbers that are wildly optimistic. The only

way long-term drift can be determined is to measure it

over the time interval of interest. The LT6660 long-term

drift data was taken on over 100 parts that were soldered

into PC boards similar to a “real world” application. The

boards were then placed into a constant temperature oven

measured with an 8.5 digit DVM. Figure 5 shows typical

long-term drift of the LT6660s.

Hysteresis

Hysteresis data shown in Figure 6 and Figure 7 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 dissipat-

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

DFN package is 102°C/W and this dissipation causes a

36°C internal rise. This elevated temperature may cause

the output to shift due to thermal hysteresis. For highest

performance in precision applications, do not let the

LT6660’s junction temperature exceed 85°C.

Input Capacitance

It is recommended that a 0.1µF or larger capacitor be

added to the input pin of the LT6660. This can help with

stability when large load currents are demanded.