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A dual DC/H-bridge driver, designed as a drop-in replacement for a standard stepstick.
Can drive two DC motors, or be used as four independent half-bridges.
Designed around the TB67H453FNG IC. Datasheets can be found here.
en pin, just like a standard stepstickYou can use the Pololu_Breakout_A4988 symbol from the default KiCad library, with its accompanying default footprint. Here is a pinout correspondence for the pins :
| StepStick DC Driver | Pololu A4988 |
|---|---|
| OB1 | 1B |
| OB2 | 1A |
| OA2 | 2A |
| OA1 | 2B |
| IA2 | DIR |
| IA1 | STEP |
| IB2 |
| RESET |
| IB1 | MS3 |
| MSB | MS2 |
| MSA | MS1 |
| VCC | VDD |
| NC | SLEEP |
[!WARNING] You need to add a 100uf capacitor between the
VMandGNDpins.
If the resistors on the BOM are respected, the maximum intensity per channel can be configured by setting the Vref voltage :
Imax(A)=Vref(v)
The driver will regulate the intensity to prevent it from getting higher.
The configuration is common to both H-bridge.
Channel A and B are both controlled by their own two pins Ix1 and Ix2.
They are 3 ways to control the outputs, configured respectively by MSx :
| MSx | Mode |
|---|---|
| L | Phase/Enable control |
| H | PWM control |
| Hi-z/Open | Individual half bridge control |
| Ix1 | Ix2 | Ox1 | Ox2 | Mode |
|---|---|---|---|---|
| L | L/H | L | L | Short Brake |
| H | L | L | H | Reverse |
| H | H | H | L | Forward |
| Ix1 | Ix2 | Ox1 | Ox2 | Mode |
|---|---|---|---|---|
| L | L | Hi-Z | Hi-Z | Coast |
| L | H | L | H | Reverse |
| H | L | H | L | Forward |
| H | H | L | L | Short brake |
| Ixx | Oxx | Mode |
|---|---|---|
| L | L | Short Brake |
| H | H | Reverse |
[!NOTE] Current limiting does not work in half bridge mode, so beware of currents!
If left open, a pin will be pulled down (considered L). If you do not want to use one of the channels, you can simply not connect the output to anything.
The constraints have been set up for Aisler's Beautiful Boards service.
It is advised to use a .8mm total thickness instead of the standard 1.6mm to improve the thermal dissipation.
When an overcurrent event happens, the driver deactivates for 25us. In the event of a short circuit, this means the driver will be off most of the time, and so the measured intensity (mean intensity) will be very low, and so the driver cannot be used to regulate current.
No overheating was found when used at .8A on one channel. Further testing is necessary.
See here.
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