I am interfacing with an msp430 and need to use vdrive @3.3v. My problem is that the logic supply rises to 3.8v when the vdrive pin is connected to logic supply. There are no application notes regarding supply sequencing that I have found. I have an evaluation board but the supplied schematic does not match the layout so its not much help.
Can you tell me which kit you have and which user guide you are using? The reason I ask is that this particular product has two hardware designs supporting it. The older of the two was designed…
Can you tell me which kit you have and which user guide you are using? The reason I ask is that this particular product has two hardware designs supporting it. The older of the two was designed to work with our old CED controller board while the newest board has been designed to interface with our SDP-B controller board.
If you are using the kit described in UG-709 you'll want to use the design files provided at this link:
Otherwise if you are using the EDZ kit you'll want to use the following
If that still doesn't help let me know the details of the kit you are using and I'll try to help you sort it out.
UG-709 was the schematic I needed. Do you have any suggestions regarding interface to 3.3v logic devices?
Are there any pins that should not be tied to 3.3V logic devices when Vdrive=3.3V?
I'm assuming you are going to be using the pin headers to bring your signals over from the MSP430 board including your power and ground. If so I would recommend removing the ADG3308's as the SDP connector side will be floating and this could cause you a headache.
I would then bring the power in through LK703.
actually I have my own prototype board built . Whenever I connect Vdrive to the 3.3V supply it causes it to rise to 3.8V. I was trying to go back to the eval kit to attempt to duplicate the problem.
The MSP430 does not have 5V -tolerant IO so I am forced to use Vdrive=3.3V
schematic snippet :
The AVDD connection to pin 18 is 5V and needs to be changed to DVDD at 3.3V. The 3.3V supply rises when that connection is moved to DVDD
Yes I think that and what the connection to R70. You probably want to change that to DVDD as well