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Twist Board Datasheet v1.4.1

Overview

The Twist Board is a reprogrammable, bi-directional 300W power converter. It features a dual 12V to 72V low side and a single 10V to 110V high side. The maximum current per power channel is 8A. The power channels can be used independently, providing two output voltages, or combined to double the current capacity.

The Twist Board is fully open-source, compatible with either the SPIN board or other programming systems. It supports communication via CAN-bus or RS-485.

Check

  • Rated Power: 300W
  • Number of Low-Side Channels:
    • Dual Low side
    • Single High side
  • Current ratings:
    • 8A per channel
    • 16A in parallel
  • Voltage Ratings:
    • 12V to 72V low-side
    • 12V to 100V high-side

Attention

  • 2-phase design
  • Dual or Single power channel configuration
  • Up to 97% efficiency
  • Standard size: 100mm x 160mm x 35mm
  • Wide voltage operating range
  • DC or AC operation
  • Parallel connection for higher power
  • CAN-bus and RS-485 communication compatible
  • Fully open-source
  • Voltage and current mode libraries available
  • Github Repository

Converter Pinout

The TWIST converter pinout is shown in the image below.

Converter pins

Power Pins or feeder pins

  • Vhigh is the high side voltage
  • Vlow is the low side voltage. There are two channels 1 and 2.
  • GND is the power GND
  • Feeder 6V is the 6V output of the embedded feeder
  • D6V is the input of the digital +6V. You can feed it from an outside source.
  • DGND When feeding from an outside source, connect your ground on the pin next to D6V

Data Pins

  • CAN1 and CAN2 the two pins of the CANBus
  • RS485 +/- the two pins of the RS485 bus.
  • Analog +/- the two pins of the analog bus.
  • Sync I/0 the pin through which boards synchronize. It is the same pin for both master and slave operation.
  • DGND is the digital ground

Electrical Specifications

Absolute Maximum Ratings

Absolute Maximum Ratings

Parameter Min Typ Max Unit
Low-Side Voltage - - 90 VDC
High-Side Voltage 8 - 110 VDC
Low-Side Peak Current per Channel - - 10 A
Power Output - - 300 W

Low-Side Ratings

Parameter Min Typ Max Unit
Number of Power Channels - - 2 -
Voltage Range 12 - 72 VDC
(Max Low-Side Peak Current per Channel) - - 8 A
Voltage Ripple - - 0.3 VDC

High-Side Ratings

Parameter Min Typ Max Unit
Number of Power Channels - - 1 -
Voltage Range 12 - 100 VDC
Voltage Ripple - - 0.3 VDC

Switching Characteristics

Parameter Min Typ Max Unit
Switching Frequency - 200 - kHz
Selectable Deadtime (20kΩ resistor) - 200 - ns
Maximum Gate Current - 4 - A

Temperature and Dimensions

Parameter Min Typ Max Unit
Operating Temperature -20 - +60 °C
Cooling Principle - Natural Convection - -
Dimensions (L x W x H) 100 x 100 x 35 - - mm

Protection Features

Parameter Min Typ Max Unit
High-Side Fuse (Tamb = 25°C) - 8 - A
Low-Side Fuse (Tamb = 25°C) - 8 - A

Communication Specifications

CAN-FD

Type Parameter Min Typ Max Unit
CAN-FD Baudrate 500 500 - kBauds
Halh Duplex RS485 Baudrate 10 20 - MBauds
SPI Baudrate 0.5 - 20 MBauds
USART Baudrate - 115200 - Bauds

Synchronization

Two Twist Boards can be synchronized via PWM sinc IN/OUT. Using a 15cm RJ45 cable, the delay and jitter between the server and the client PWM are measured as follows:

Parameter Symbol Min Typ Max Unit
PWM Slew Rate - 660 - - mV/ns
Delay Between Server and Client td - 24.2 - ns
Jitter of PWM Client tj - 4.8 - ns

Synchronization experiment results

Analog Communication

Analog communication between boards allows voltage and current measurement with high accuracy.

Example Measurement: - A 16-bit value of 2000 is transmitted by a server board. - Step response from 1V to 1.25V measured with a 500 MHz oscilloscope.

Parameter Symbol Min Typ Max Unit
Step Response Time to ±5% Δt5% - 1.7 - µs
Steady-State Value Vfinal - 1.25 - V
±5% Steady-State Interval ΔV - 0.125 - V
Bandwidth \(\(fc = \dfrac{3}{2\cdot \pi \cdot \Delta t_{5\%}}\)\) - 281 - kHz

Measurement resolution results

Statistical Distribution of 10235 data samples

Parameter Symbol Min Typ Max Unit
Mean \(\mu\) - 2032.65 -
Variance \(\sigma^2\) 0.795 -

Measurement resolution results

Measurement Chains

The Twist Board implements full observability on all low-side and high-side power channels using isolated measurements.

ADC Specifications

Parameter Value
ADC Technology Successive Approximation (SAR)
Independent ADC Peripherals 5
Number of Channels per ADC 1 to 6
Sampling Time 530 ns
Hardware ADC Trigger Programmable trigger instant on PWM period
Number of PWM synchronized ADCs 2
Software ADC Trigger All ADC peripherals
Trigger Event Typical Frequency 200 kHz

Measurement Points

Measurement Description Sensor Technology Bandwidth (kHz) Signal Side Amplitude Full Scale Range Unit
VILow1 Low-side voltage Voltage divider & isolation amplifier 60 ±250 mV ±80 V
iILow1 Low-side current Isolated Hall effect sensor 1000 ±20 A ±10 A
VILow2 Low-side voltage Voltage divider & isolation amplifier 60 ±250 mV ±80 V
iILow2 Low-side current Isolated Hall effect sensor 1000 ±20 A ±10 A
VIHigh High-side voltage Voltage divider & isolation amplifier 100 +2 V 120 V
iIHigh High-side current Isolated Hall effect sensor 1000 ±20 A ±20 A
Temp1 LEG1 Temperature NTC Thermistor -40 to +110 \(\degree C\)
Temp2 LEG2 Temperature NTC Thermistor -40 to +110 \(\degree C\)

Schematic showing where the measurements are performed on the circuit.

Measurements location and output convention

  • Voltage sensors - they are connected at the input/output of the TWIST board
  • Low-side Current sensors - they are connected right next to the inductor and measure inductor current. Their output is positive when the converter is in BUCK mode (current going OUT of the low side).
  • High-side Current sensor - it is connected right next to the high side connector. Its output is positive when the converter is in BUCK mode (current going IN of the high side).

Image showing where the measurements can be accessed on the board.

Measurement pins

All measurements have pins which can be easily accessed with a probe (oscilloscope or multimeter) as shown below.

Warning

Board with measurement points

Standard Deviation of Measurements

Parameter Not Averaged Avg of 2 Measures Avg of 3 Measures Avg of 5 Measures Avg of 10 Measures
VILow1 85 mV 61 mV 50 mV 39 mV 28 mV
VILow2 82 mV 58 mV 47 mV 37 mV 27 mV
VIHigh 150 mV 108 mV 88 mV 68 mV 48 mV
IILow1 34 mA 24 mA 20 mA 16 mA 11 mA
IILow2 34 mA 24 mA 20 mA 15 mA 11 mA
IIHigh 14 mA 10 mA 8 mA 6 mA 4 mA

Relative accuracy of voltage and current measurements

The following graphs give the accuracy of the voltage and current measurements for different levels of current and voltage.

Accurary graphs

Theoretical Calibration Parameters

By default all TWIST boards can be calibrated using the following parameters.

Variable Name Gain Offset Unit
VLow1 0.045 -94.364 V
VLow2 0.045 -94.364 V
VHigh 0.029964 0 V
ILow1 0.005 -10 A
ILow2 0.005 -10 A
IHigh 0.005 -10 A

Typical Applications

Mode Name High Side Low Side Electrolytic Capacitor Typical Application
DC-DC Buck Input Output ON Battery Charger
DC-DC Independent Input Output ON Reprogrammable Power Supply
DC-DC Boost Output Input ON Fuel-Cell Converter
1-Phase DC-AC Buck Inverter Input Output OFF AC Micro-Grids
1-Phase DC-AC Buck PFC Input Output OFF AC Micro-Grids

Example wiring diagram and schematic of the Twist board in Buck mode

Example wiring diagram and schematic of the Twist board in Independent mode

Example wiring diagram and schematic of the Twist board in Boost mode

Example wiring diagram and schematic of the Twist board in Boost mode

Example wiring diagram and schematic of the Twist board in PFC mode

!!!warning The AC source shown below must be low-voltage (below 90V peak)

Mechanical Specifications

Below is the Twist converter assembly view.

TWIST mechanical view

Revision History

Date Revision Changes
07-Fev-2025 1 Initial Release

License: Documentation licensed under Creative Commons SA-BY