Due Dates:

• Requirements/Considerations -

• Component Selection -

• Initial Schematic -

• Initial Layout -

• Rev. A Ordered -

• Firmware/Testing -

Description/Purpose

• Measures voltages from battery and motor and sends them to VCU. Contactor signals also run through here

Requirements

• Step-down HV outputs from battery and motor to 3.3V

Application Note

Context

Location of the board: Inside PDE

Connection List

Main

Schematics

Precharge Resistors: 3 parallel 330 ohm resistors with a fourth DNP included just in case.

Voltage Divider: Takes the 120V signals and steps them down to the 3.3V range.

Isolating Amplifiers: Passes the signals from HV side to LV side of the board. Also applies a gain of 0.4.

Subtracting Amplifiers: Subtracts positive and negative from isolating amplifiers before applying a gain of 2.5 to counteract the isolating amplifier gain.

0.8V Reference Circuit (N/A): Was removed after discovering that shorting the negative output terminal on the isolating amplifiers to ground changed the intended 0.4 gain to 0.2. Also in part due to the TLV9001BDVR having clipping at around 2.4V for some reason.

Circuit Components

Layout

Github link:

PCB:

3D Model

Firmware

Drivers

High-Level (Block Diagram)

Rev B Testing Plans

• Solder all remaining components (Fuses, Pin headers, Diodes, Precharge Resistors?)

• Verify output voltages for all ICs on the board

  • Confirm that 5V is being outputted from the ISO DC/DC

    • 5.14V

  • Confirm that 3.3V is being outputted from the LDO

    • 3.29V

• Verify both AMC1350s apply a 0.4 gain to the input

  • Verify the TLV9002 single ended output is correct

• Test RPP

• Measure precharge and divider resistances so more accurate numbers can be used in firmware

  • Check precharge resistance

    • 109.9 Ohms (Calculated: 110 Ohms)

  • Verify voltage divider circuit correctly steps voltage down

    • Important Note: There is some strange behavior when measuring resistance across the 100k resistors after soldering them on

    • Battery Resistor Values: 51.2k (100k) and 2.48k [R20 and R21]

    • Motor Resistor Values: 51.2 (100k) and 2.477k [R22 and R23]

  • Test 13V - 130V in 13V increments

    • HV+ (Battery)

      • 136.3V = 3.336V

      • 130V = 3.175V

      • 117V = 2.855V

      • 104V = 2.535V

      • 91V = 2.215V

      • 78V = 1.896V

      • 65V = 1.578V

      • 52V = 1.26V

      • 39V = 0.944V

      • 26V = 0.63V

      • 13V = 0.312V

    • HV- (Motor)

      • 136V = 3.332V (1.337V)

      • 129.6V = 3.172V (1.273V)

      • 116.6V = 2.852V (1.144V)

      • 103.6V = 2.532V (1.016V)

      • 90.6V = 2.212V (0.887V)

      • 77.6V = 1.893V (0.759V)

      • 64.7V = 1.674V (0.631V)

      • 51.7V = 1.257V (0.504V)

      • 38.7V = 0.939V (0.376V)

      • 25.7V = 0.623V (0.249V)

      • 12.7V = 0.308V (0.122V)

• Integration with Bomb Board

  • Precharge time testing?