Hello,
I'm currently evaluating the DAC of LPC5536-EVK.
After reading the reference manual, it's still not clear to me what to do with DAC's "current sources":
48.1.4. To initialize the DAC module:
...
- Enable VREF module (PDRUNCFGCLR0[PDEN_VREF] = 1) in PMC register. DAC PTAT and ZTC current sources comes from VREF module.
This does not explicitly state to enable these current sources. Do I have to enable them, maybe both of them?
This is a valid question as these current sources can be enabled separately in Global Control register (GCR):
Bit 21 IREF_ZTC_EXT_SEL
External On-Chip ZTC Current Reference Select
Selects the external ZTC current reference, which is from the VREF module. See the Chip-specific section for more information.
0 - Not selected
1 - Selected
Bit 20 IREF_PTAT_EXT_SEL
External On-Chip PTAT Current Reference Select
Selects the external PTAT current reference, which is from the VREF module. See the Chip-specific section for more information.
0 - Not selected
1 - Selected
*rant* Here, the current source is called "current reference". What has driven the author to suddenly change the terminology? This is a technical document. Choose your term and stick to it! *rant end*
Further, the chip-specific section does not contain more information on these current sources. Where is it?
What is the advantage / disadvantage of PTAT or ZTC current source? The product data sheet is silent about their characteristics.
Please advise!
Thanks.
Daniel
