Hello everyone!
I'm working on a project where we are using the AD5750-1 ICs as current drivers (CDs), and I need some assistance diagnosing an issue we’ve encountered.
Project Overview:
We have two AD5750-1 ICs connected to a single SPI bus on one of our boards. Each IC is configured with a unique address (0 for the first IC and 1 for the second), and both are used as current drivers. The system operates with a unipolar power supply of +24V and GND.
The Issue:
Our software team is able to communicate and control the first current driver (address 0) with no issues; however, the second IC (address 1) on the same SPI bus is completely unresponsive. We have conducted several tests, but the second current driver refuses to operate or respond to commands.
In addition, we have a second board where we are using four AD5750-1 ICs (also connected to the same SPI bus), and none of the current drivers on that board are functional, despite the first IC on the original board working as expected.
Additional Details:
- SPI Clock: We've tested various clock values, all below 5 MHz.
- Bus Length: The length of the SPI bus is no more than 60 cm.
- Level Shifters: There are some level shifters in the signal path from the MCU to the ICs, but the signals appear clean and correct on the oscilloscope. As mentioned, the first CD works perfectly with the current setup, so signal degradation shouldn’t be the issue.
What We've Tried So Far:
- Hardware Verification: I’ve reviewed the schematic, and the second CD’s connections are identical to the first CD, aside from the address lines. Power is supplied as expected (+24V), and the ground connections are solid. Decoupling capacitors and other passive components seem to be in place correctly.
- Software Investigation: Our programmers have confirmed that the SPI communication is functional for the first IC, but they are unable to communicate with the second IC. They are following the same procedures for addressing and communication.
- Experiments: We've tried several approaches to isolate the issue but have yet to identify a clear root cause. All SPI lines (MISO, MOSI, SCK, CS) appear to be functioning as expected for the first IC, but there seems to be no response from the second IC on the bus.
Schematic:
Below is the schematic for the first current driver. The second CD has an identical connection, except for the address lines, which are set to a different value.
Any insights or advice you can provide would be greatly appreciated! We’re open to trying new diagnostic approaches or testing methods to resolve this issue.
Thanks in advance for your help,
Aleks.
