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FrontRear

Peripheral Displays & Cameras

(Use a simple circuit to distribute the current) 

Solar Master (Front)
Steering BoardSolar Master (Rear)
Pedal BoardRear View Camera
FanFan
SpareTelemetry
SpareCharger Interface

Potential Parts

Part NumberLoad CurrentRds OnNumber of OutputsAnalog Current Sense
TPS2H160BQPWPRQ12.5A155mOhm2
BTS71202EPAXUMA12A61mOhm2+/-30% @ 50mA, +/-11% @ 500mA
AUIPS7091GTR1.5A80mOhm1+/-8% @ 50mA, +/-3% @ 500mA
AUIPS7081RTRL2A55mOhm1

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Current Limit: < 20A @ 12-13.5V

FrontRear

Spare

Front Power Distribution

(around 16A at the maximum)

Spare

BMS Carrier (Master & Slave)

(due to high inrush current to the relays)

Front Power Distribution

(around 16A at the maximum)

Potential Parts

Part NumberLoad CurrentRds OnCurrent Mirror Error
BTS70041EPPXUMA115A4.4mOhm± 8% @ 10 - 15A
AUIR3313STRL23A (Adjustable)5.5mOhm± 5%
BTS70021EPPXUMA121A (Fixed)2.6mOhm± 5%

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The target power consumption of MSXIV's LV system is 20 W. A reasonable accuracy will be the +/- 0.1% of the total power. Given the supply voltage will be 12-13.5 V, the current sensing circuit should be more accurate than +/-  1.5 mA.

Mathinline
body\dfrac{20\, W}{13.5\, V} \cdot \pm0.1\%=\pm1.5\, mA

Locations

Given the HSD will be responsible for disconnecting the load when it is shorted to ground, there is no safety advantage for high side current sensing. There are three locations for the current sense resistor:

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  • High-Side
    • High immunity to ground disturbance
    • The common-mode voltage tolerance of the differential op-amp must be greater than 12V
  • HSD Current Mirror
    • A HSD built-in current mirror with high gain plus a current sense resistor should use less power than the low-side sensing (needs proof)
    • The accuracy is around +/- 30% for low current (< 100 mA)

Block Diagram

Image Added

Ports

Front

BoardNom. Current (A)Max. Current (A)ConnectorHSD
Peripheral Displays & Cameras0.2780.329
Light
Front Lights Board1.8894.163
Heavy
Steering Board0.0170.071
Light
Pedal Board0.0130.067
Light
Center Console0.9522.146
Light
Horn08
Heavy

Rear

BoardNom. Current (A)Max. Current (A)ConnectorHSD
Motor Interface0.1794.958
Light
BMS Carrier (Master & Slave)0.81419.800
Heavy
Solar Master0.1500.482
Light
Rear Lights Board0.0222.879
Heavy
Rear View Camera0.50.5
Light
Charging Interface0.0260.133
Light
Front Power Distribution 3.25015.97
Heavy