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TLV5637 DELAY

ANOOP G S
Intellectual 305 points
Other Parts Discussed in Thread: TLV5637

sir. 

 

1.DAC Speed will be considered as an addition of settling time and writing speed.Or the settling time only come to play .

2.I am using fullspeed(20MHz) for writing.then one bit updation takes 0.05uS so all 512 steps(512*16*0.05=409.6us) any delay between two write, is this true. Then (409.6+settling time)=409.6+208=617.6us(time) is this calculation right for achieving full scale ramp.

3.is it needed to go in the above way or i have to consider only the seettling time only and go ahead.

4.what is the difference between fast and slow mode(technical other than speed).

 

regards.

Anoop

 

  • 0
    TI__Guru**** 181021 points

    Hi Anoop,

    My appologies here - I gave you some bad information in your previous post.  I simply took the settling time and multiplied that without factoring in the time it takes to write to the TLV5617.  Normally the speed of a DAC, like the TLV5637, is considered using both the time it takes to write a data word into the part along with the time it takes to settle to within 1/2LSB of a new value.  

    So, starting over...16 cycles of your 20MHz clock is 800ns.  Consider that the new output value (n) settles while you are writing input code (n+1).  The /CS input needs to toggle between updates, so you need to factor in at least one SCLK between steps.  You would be looking at something like 512*17*50ns or 435us.  To stay under your 200us ramp rate then you would have to stay under 235 steps.

    The main difference between fast and slow modes is the output driver - you have more current available to drive the outputs in fast mode which impacts slew rate and power consumption.

  • 0 in reply to Tom Hendrick
    Intellectual 305 points

    hello sir,

     

            sorry for the late reply.so if we go for 235 steps we get two delays writing delay-199.750us & settling time- 0.4*235=94us as these are parallel we would take 199us as the over all delay.am i correct.

     

    regards

    Anoop

  • 0 in reply to ANOOP G S
    TI__Guru**** 181021 points

    Hi Anoop,

    Yes, that is correct.  Please be aware that the 0.4us settling time is a 'typical' value, so over a full production cycle, you may see some parts settle a little slower.

  • 0 in reply to Tom Hendrick
    Intellectual 305 points

    sir,

                            Thanks for your kind support.

    regards

    Anoop