Hi Avnish,
Thank you for contacting Engineer Zone regarding the AD9253. Can you please try setting the transfer register? So the commands will be
1. SPI_Write (0x05, 0x0E); Only send commands to Channels B, C, D
2. SPI_Write (0x22, 0x01); Power down Channels B, C, D
3. SPI_Write (0xFF, 0x01); Send the transfer bit
Thanks
Umesh