LDAC operation

Question

Hi 
 1. I am writing driver for AD5676R. I found that only using command 0x0001, LDAC follow the timing rules (pull up, pull down then pull up). 
 
 After loading the program to the mcu, these three channels have outputs (full scale). But I think they shouldn't have outputs because 0x2 command did not write to the DAC, that's right? But why do these channels still have outputs? 
 2. For LDAC mask: 
 If I set /LDAC bits is 0xFF, that means /LDAC pin is overrided. That is to say, whether LDAC pin is low or high, dac will always an output once using command 0x1 and 0x2?

iandal · Accepted Answer

Hi mashimaro 
 For item 1. In your command sequence, there is a line for LDAC Mask with data 0x0. This means that LDAC mask was not enabled. So when you write to the DAC using command 0x1 the data is written to the Input Registers and when you toggle LDAC via GPIO. They get loaded to the DAC registers and reflect at the vout pins. 
 2. Do you mean setting LDAC Mask register, command 0x5, to 0xFF? If that's so, the LDAC Mask will be enabled, and LDAC I/O activity will be ignored by all channels. The only way to update the DAC outputs would be using command 0x1 + 0x2, or using command 0x3 which directly updates the addressed channel. 
 Best regards, 
 Ian)