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EBI

EBI. (Electronic Battery Indicator). Calibration. Project #61 done by Ryan Lindsay in conjunction with ITW. EBI Sensor. Snell’s Law: θ c = arcsin(n 2 /n 1 ), n 1 = n of S.A.N., n 2 = n of Battery Acid. Objective. Provide a Means to Calibrate EBI Sensor. Calibration must be:

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EBI

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  1. EBI (Electronic Battery Indicator) Calibration Project #61 done by Ryan Lindsay in conjunction with ITW

  2. EBI Sensor Snell’s Law: θc = arcsin(n2/n1), n1 = n of S.A.N., n2 = n of Battery Acid

  3. Objective Provide a Means to Calibrate EBI Sensor • Calibration must be: • Quick: take less than 30 seconds • Accurate: trim output to within ±50mV of desired output • Efficient: use as few extra calibration wires as necessary • Self-Contained: calibration done after sensor assembly • Design freedoms: • Cost can be relatively high (ASIC): high volume • Can redesign circuit to accommodate calibration

  4. Original Design Design Features: • Photodiode & I.R.E.D. (935nm) • Photovoltaic mode • Resistor configuration temperature stable • Supply voltage filter • 2 op-amps / 2 pots. (gain & offset)

  5. Calibration Circuit Anti-Fuse – Zener Zap 1 wire = 4 combinations, 3 wires = 64 combinations

  6. Calibration Circuit Fuse 1 wire can be any # of combinations (fuse accuracy)

  7. Calibration Circuit Applying Fuse Technology • Through QS-9000 statistical analysis: • Gain  38 fuses/resistors • Offset  28 fuses/resistors • Specifications met: • P(max) < 1/16 W/resistor • Vcal(max) < 100 V • ΔVcal > 1.0 V • Fuses do not blow in normal operation

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