ISL71590SEH

8

June 3, 2016

FN8376.2

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support circuitry necessary with other thermal sensors such as

thermistors, thermocouples and other discrete based solutions.

External linearization circuitry, precision voltage amplifiers,

resistance measuring circuitry and cold junction compensation

are not needed when applying the ISL71590SEH.

In the simplest application, the ISL71590SEH, a resistor, a power

source and any voltmeter can be used to measure temperature.

Ideally resistors used should be of a metal film or metal strip

type, such resistors having very low thermal coefficient values.

When voltage is initially applied to the ISL71590SEH, the circuit

ramping up typically 2µs after. There will be an initial short

reading is available. See Figures 15 through 18 for scope shot

examples.

The output characteristics also makes the ISL71590SEH easy to

multiplex; with either or both the input supply voltage or the

output current can be switched by a CMOS multiplexer such as

the HS-508 or HS-1840 from Intersil.

When the ISL71590SEH die product is used, the die substrate

should be tied to the more negative of the 2 terminals for

optimum performance.

Parameter Glossary

The ISL71590SEH parametric specifications provide for an

understanding of the temperature sensor performance

over-temperature and radiation exposure. Following are critical

parameter explanations as they relate to usage and

interpretation.

Ambient Error Accuracy refers to the maximum error at an

ambient temperature of +25°C and is expressed as

0.5°C of

The Absolute Error without External Calibration describes the

temperature accuracy over the entire -55°C to +125°C range. The

typical performance is shown in Figure 8 on page 5. Both of

these two first specification explanations are to be considered as

initial error accuracy specifications.

specified accuracy after 50krad(Si) at 0.01 rad(Si) per second

(LDR) and 300krad(Si) at 70 rad(Si) per second (HDR) exposure.

This radiation hardness performance is unmatched in the

industry for this class of device, this performance is shown in

Figure 2 on page 1 as a delta over radiation type and in Figure 19

on page 7 as an absolute measurement.

Non-Linearity in referring to the ISL71590SEH, is the maximum

allowable deviation of the output current over-temperature for

any single part relative to its individual best fit line over 5 discrete

temperature (-55°C, -15°C, +25°C, +85°C, +125°C) points. This

performance is guaranteed by testing.

Repeatability Errors arise from a strain hysteresis of the

package. For the ISL71590SEH this is the maximum deviation

between +25°C readings after a single temperature excursion

between -55°C and +125°C, and is guaranteed by

characterization and is not tested. The magnitude of this error is

solely a function of the magnitude of the temperature span and

duration over which the device is exposed.

Long Term Drift Errors are related to the average operating

temperature and the magnitude of the thermal shocks

experienced by the device. Extended use of the ISL71590SEH

temperatures at +125°C typically results in long-term drift of



0.05°C after 1khr with a specification of - 0.25°C to +0.25°C.

Trimming Out Errors

The ideal graph of current versus temperature for the

ISL71590SEH is a straight line, but as Figure 20 on page 9

shows, the actual shape is slightly different (exaggerated greatly

for explanation). Since the sensor is limited to the range of -55°C

to +150°C it is possible to optimize the accuracy by trimming.

Trimming extracts the maximum performance from the sensor.

The circuit in Figure 21 on page 9 trims the slope of the

ISL71590SEH output. The effect of this is shown in Figure 22 on

page 9.

The circuit of Figure 23 on page 9 trims both the slope and the

offset.

Starting in Figure 24 on page 9 with an untrimmed slope, then

progressing through to Figure 27 on page 10 each figure showing

the effect of adjusting the offset and slope and finally the offset

again to finally arrive at an optimized condition.

The diagrams curvatures are highly are exaggerated to show

effects, but it should be clear that these trims can be used to

minimize errors over a partial or the entire temperature range.