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LT6372-1

Rev. 0

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APPLICATIONS INFORMATION

Error Budget Analysis

The LT6372-1 features a split reference configuration pro-

viding a convenient and effective way to interface a bipolar

swing to an ADC input without additional precision com-

ponents. Performing the same level shift with traditional

intsrumentation amplifiers as shown in Figure 11 requires

external precison components which decrease accu-

racy, increase cost and occupy valuable PCB space. The

error budget in Table 2 shows the total system error of a

LT6372-1 used as a bridge amplifier.

Table 2. Error Budget

ERROR SOURCE

CALCULATION

ERROR, ppm OF FULL SCALE

LT6372-1

Absolute Accuracy at TA = 25°C

Gain Error, %

Input Offset Voltage, µV

Output Offset Voltage, µV

Input Offset Current, nA

CMRR, dB

Gain Error in % • 10k + 1000

VOSI/20mV

[VOSO/100]/20mV

[(IOS)(350)/2]/20mV

[(CMRR in ppm)(5V)/20mV

2200

3000

137.5

12.25

250

Total Accuracy Error

5599.75

Drift to 85°C

Gain Drift, ppm/°C

Input Offset Voltage Drift, µV/°C

Output Offset Voltage Drift, µV/°C

(Gain Drift + 10ppm/°C)(60°C)

[(VOSI Drift)(60°C)]/20mV

[(VOSO Drift)(60°C)]/100/20mV

2700

1800

120

Total Drift Error

4620

Resolution

Gain Nonlinearity, ppm of Full Scale

Typ 0.1Hz to 10Hz Voltage Noise, µVP-P

(0.1Hz to 10Hz Noise)/20mV

Total Resolution Error

Grand Total Error

10279.75

G = 100

All errors are min/max and referred to input.

350

10V

PRECISION BRIDGE TRANSDUCER

LT6370A MONOLITHIC

INSTRUMENTATION AMPLIFIER

G = 100, RG = ±0.1%, ±10ppm TC

6372-1 F10

243

REF1

REF2

5V REF

LT6372-1

Figure 10. Precision Bridge Amplifier Using LT6372-1

Figure 11. Precision Bridge Amplifier with External Level Shift

350

5V REF

350

10V

PRECISION BRIDGE TRANSDUCER

LT6370A MONOLITHIC

INSTRUMENTATION AMPLIFIER

G = 100, RG = ±0.1%, ±10ppm TC

6372-1 F11

243

REF

LT6370A

–

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