FTDI Community
General Category => Discussion - Hardware => Topic started by: N.H on February 05, 2022, 04:33:11 AM
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Hi
I am using FT234XD.
The power supply method is using the USB self-powered method.
There is an explanation to use "VBUS_SENSE" for reset in the item "6.2 Self Powered Configuration" of the specification sheet "DS_FT234XD.pdf", but it does not exist in the IC of this model.
I would like to use the Vbus from USB divided by two resistors and connect it to "RESET#" instead.
Let's consider the conditions under which USB becomes active without system power supply.
1) When the voltage is applied only to "RESET#", does it cause latch-up or other defects?
2) Is there a problem with leaving "RESET#" unconnected (OPEN) in order to avoid latch-up concerns?
Is there a possibility that the USB circuit will become inoperative because reset does not occur every time the USB Connector is inserted or removed?
The spec sheet also states that the RESET# pin can be Open when not in use.
Since the PCB is complete, I would like to know if there are any problems with methods 1) and 2) first.
I used a translation site.
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Hi,
There is an integrated Reset Generator Cell which provides a reliable power-on reset to the devices internal circuitry at power up. The RESET# input pin allows an external device to reset the FT234XD. RESET# can be tied to VCCIO.
Regards
FTDI Community
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Hello.
thank you for answering.
I understand how POR works.
I am concerned about the following two conditions.
1.
・Self Power OFF (SYSTEM Power OFF)
and
・ (Connection USB Cable or Power ON USB Host Sysytem)
Q:The voltage rises only at the #RESET pin of FT234, but does it shift to a failure mode such as latch-up?
2. Is there a problem with leaving "RESET#" unconnected (OPEN) in order to avoid latch-up concerns?
CASE:I considered the case of operating in the order of 2-1)->2-2)->2-3)->2-4)
2-1) SYSTEM Power ON and (Non Connection USB Cable or Power OFF USB Host Sysytem )
Occurs POR.
2-2) USB Plug Connection or USB Host Sysytem Power on
2-3) USB Plug DisConnection or USB Host Sysytem Power Off
2-4) USB Plug Connection or USB Host Sysytem Power on
Q:No reset occurs between 2-3) and 2-4), is there any problem for ft234?
(I'm using Google Translate.)