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LTC4332 SS1-3 Pins

Hello

I am trying to use 2 LTC4332 ICs at default configuration. Do I need to use SS1-3 pins on the local side? Can I just simply connect them to GND or VL? Also when trying to send data to remote side, SSC pin of the IC is set to high. This is correct right?

  • Hi,

    The SSC pin is used to access the internal registers of the local LTC4332. The SSC1-3 are used to select individual remote SPI slave devices. So if the intention is to communicate with a remote SPI slave device, one (and only one) of the SS1-3 will need to be asserted on the local LTC4332. That chip select signal will be reproduced on the remote side LTC4332. 

    Jason

  • Hello Jason or anyone that can help. According to the datasheet of LTC4332 page 22, the MCU_SS1 is connected to SS1 and MCU_SS4 is connected to SSC. For a system that does not have MCU_SS1 and MCU_SS4, but only CS/chip select to one device, where this master CS/chip select should be connected to? I am fully understand the connection on the remote side, just SS1 connected to one CS or chip select of the slave. Also, neither my MCU or my slave have INT pin. Thanks you. 

  • Hello Gurhalil, I assume your question here is about the remote slave side? What should the remote LTC4332 's SSC pin connected to? is this what you asking? just fyi the datasheet at page 6, said, for SSC (REMOTE = 0) and When remote mode , leave SCC unconnected .  Also, what your final configuration looks like? Thanks

  • If your MCU only has 1 nCS pin, then it can only talk to one SPI device.  To talk with multiple SPI devices, you'll need some way to direct the MCU's SPI signal to the proper device such as a decoder or de-multiplexer.   Which nSSx pins you'll use depends on what you are trying to talk to.  The nSSC pin is used to talk to the local LTC4332's internal SPI device.  nSSC1-nSSC3 are used to talk with the remote SPI devices. 

    If your application only has 1 SPI device and you don't need to change the LTC4332's configurations (or want to interact with the LTC4332's internal SPI device), then simply connect the MCU nCS pin to the nSSx pin your remote device is connected to. 

    The INT pin is present to support applications where the remote device needs to communicate an interrupt to the MCU.  If your remote device doesn't need this functionality, then pull the remote nINT high.