Current Sense.md
PCB Design Notes


Current sense: INA226 datasheet <![CDATA[]]>https://www.ti.com/lit/ds/symlink/ina226.pdf#page=30<![CDATA[]]>


Schematics Design Notes


Current sense filtering <![CDATA[]]>https://www.ti.com/lit/ds/symlink/ina226.pdf#page=14<![CDATA[]]>


TODO paper about

Current-sensing techniques for DC-DC converters, H.P. Forghani-zadeh et
al. <![CDATA[]]>https://sci-hub.se/10.1109/MWSCAS.2002.1186927<![CDATA[]]>

<![CDATA[]]>https://rincon-mora.gatech.edu/publicat/cnfs/mw02_isns.pdf<![CDATA[]]>


series sense resistor
Rds sensing
filter-sense inductor









  

  

  
DC CMRR
  
CMRR @50 kHz
  
Gain err
  
TempDrift
  
Voff
  
BW
  
gains
  
notes




  
INA281
  
+110 V
  
120-dB
  
65-dB
  
0.5%
  
20ppm
  

  
1.3MHz
  
20..500
  
cheapest TI , $1.18


  
INA310A
  
110V
  
160dB
  

  
0.15%
  
10ppm
  
20uV
  
1.3MHz
  
20..500
  
int. Comparator $1.53


  
INA310B
  
110V
  
160dB
  

  
0.5%
  
20ppm
  
150uV
  
1.3MHz
  
20..500
  
int. Comparator


  
INA169
  
60V
  

  

  

  

  

  

  

  
$1.22


  
INA791x
  

  

  

  

  

  

  

  

  
internal 50A EZ-Shunt




Reject Noise


50hz inverter
380Hz Power supply
39 kHz pwm


A loss-less technique to measure average output current:
Use an RC-Filter to measure average switch node voltage. With this V_sw_avg, Vo and the coil ESR we can compute the
current.
Note that copper has temp coeff a = 0.0043/°C (<![CDATA[]]>https://cirris.com/temperature-coefficient-of-copper/<![CDATA[]]>), so a temperature
change of 30°C results about 13% error. For an MPPT this is fairly enough, not for precise energy metering though.

<![CDATA[]]>https://sci-hub.se/10.1109/MWSCAS.2002.1186927<![CDATA[]]>

INA226
INA229