LT6650

10

6650f

APPLICATIO S I FOR ATIO

Figure 11. Worst-Case 0

°C to 70°C Hysteresis

Figure 12. Worst-Case –40

°C to 85°C Hysteresis

operation (the optimal value depends greatly on the direc-

tion and magnitude of the load current):

Hysteresis

Due to various mechanical stress mechanisms inherent to

integrated-circuit packaging, internal offsets may not pre-

cisely recover from variations that occur over tempera-

ture, and this effect is referred to as hysteresis. Proprietary

manufacturing steps minimize this hysteresis, though

some small residual error can occur. Hysteresis measure-

ments for the LT6650 can be seen in Figures 11 and 12.

Figure 11 presents the worst-case data taken on parts

subjected to thermal cycling between 0

°C to 70°C, while

Figure 12 shows data for –40

°C to 85°C cycling. Units

were cycled several times over these temperature ranges

and the largest changes are shown. As would be expected,

the parts cycled over the higher temperature extremes

exhibit a broader hysteresis distribution. The worst hys-

teresis measurements indicate voltage shifts of less than

1000ppm (0.1%) from their initial value.

Limits of Operation

The LT6650 is a robust bipolar technology part. ESD

clamp diodes are integrated into the design and are

depicted in the Simplified Schematic for reference. Diodes

are included between the GND pin and the IN, OUT, and FB

pins to prevent reverse voltage stress on the device.

Unusual modes of operation that forward-bias any these

diodes should limit current to 10mA to avoid permanent

damage to the device. The LT6650 is fabricated using a

relatively high-voltage process, allowing any pin to inde-

pendently operate at up to 20V with respect to GND. The

part does not include any over voltage protection mecha-

nisms; therefore caution should be exercised to avoid

inadvertent application of higher voltages in circuits in-

volving high potentials.

DISTRIBUTION (ppm)

–400

2

3

6

5

4

400

6650 F11

1

0

–200

0

200

600

LIGHT COLUMNS 0

°C TO 25°C

DARK COLUMNS 70

°C TO 25°C

DISTRIBUTION (ppm)

–1000

2

3

6

5

4

500

6650 F12

7

1

0

–500

1000

250

–750

–250

0

750

LIGHT COLUMNS –40

°C TO 25°C

DARK COLUMNS 85

°C TO 25°C