Node consumption

Calculation Sheet

• DOWNLOAD: File:Battery.xls

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• To update:

Battery Capacity :19Ah

Worst case for temperature(continuous operation +60'C) ->13Ah

Check if 65mA for the combined RxTx current is ok

Express the average consumption in μA ??

Include using sleep-current, awake-current, sleep-time, awake-time

MAG3110

Attention with start-up and boot-time

MSP430

Separating operations

uart-data

sensor-read

analog-read

tick

Battery life

• Calculation of hours of a year

• 24h x 365 = 8760 days/year

Using a security margin 1.14

8760 * 1.14 = 10000 hours/year

• At 20'C For a 19 Ah battery Average-Consumption is

Lasting 1 year ----> 19Ah / 10000. hours = 1900 μA

Lasting 10 years --> 19Ah / 100000 hours = 190 μA

Lasting 5 years ---> 19Ah / 50000. hours = 380 μA

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• Curves for Varta ER, D-cell
• Taking in account the temperature:

Using worst case calculation:

Continuous operation at 60'C

For the battery to last 5 years the consumption is 220 μA

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RF200

• Supply Voltage 1.8 - 3.6V
• Radio OFF current 10.2 mA
• Radio ON RX current 21.8 mA
• Radio ON TX current 85 mA
• Sleep mode 1: 1.4 μA
• Sleep mode 0: 0.27 μA

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• Net period: 180 s @1 μA
• On time 0.3 s

Using worst case senario

TX time = 50% of On-time

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• Radio-OFF time 0.15 s
• not used mode

0.15s/180 = 0.00084

10.2mA x 0.00084 = 8.6 μA

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• Rx time 0.15 s

0.15s/180 = 0.00084

21.8mA x 0.00084 = 18.32 μA

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• Tx time 0.15 s

0.15s/180 = 0.00084

85mA x 0.00084 = 71.5 μA

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• Rx+Tx Average current is 18.32 + 71.5 = 89.82 μA

Taking in account some margin

RF200 Average consumption is estimated 100 μA

MAG3110

• Supply Voltage 1.95 - 3.6V
• Active current @1.25Hz: 17.2 μA
• Active current @0.63z: 8.6 μA
• Active current @80Hz: 900 μA
• Standby current 2 μA
• Turn-on time 25 ms
• Boot time 10 ms

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MAG3110 Average current 4 μA

MSP430F2013

characteristics

• Supply Voltage 1.8 - 3.6V
• 2K Flash, 128B Ram, USI, Timer_A2,WDT, 14 pins
• 220 μA @ DCO=1 MHz, 2.2V -as advertised-
• 300 μA @ DCO=1 MHz and ACLK=32768 Hz, 3V, from FLASH
• 1 μA @ LPM3 with 32768 Hz crystal active
• 2 μs wake-up time from LPM3 @ 1 MHz
• SD16_A

• 1700 μA @ 3 V
• SD16_A Vref: 280 μA
• SD16_A Vref buffer 600 μA

• DCO configurable 1,8,12,16 MHz

Default DCO=1 MHz

Operation

• LPM3 current: 1 μA

We have to add the consumption of the active-time of:

• Tick
• uart-data
• sensor-read

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• Tick period: 250 ms @1 μA
• Tick isr time: 30 μs @300 μA
• Tick duty-cycle

30 μs/250 ms = 120 / 1000000 = 0.00012

300μA x 0.00012 = 0.036 μA

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• Uart-data period: 180 s
• Uart-data time 50 ms
• Uart-data duty-cycle

50ms /180s = 2.8 / 10000 = 0.00028

300μA x 0.00028 = 0.085 μA

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• I2C sensor period: 30 s
• I2C sensor time: 50 ms
• I2C sensor duty cycle:

50ms/30 = 0.00166

300μA x 0.00166 = 0.5 μA

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• Analog measurements using SD16_A

• Battery/temp-measure period: 30 s
• Battery/temp-measure time: 50 ms
• Battery/temp-measure duty cycle:

50ms/30 = 0.00166

2000μA x 0.00166 = 3.32 μA

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MSP430F2013 Average current 5 μA