Part Number: SN74AVC4T245
Hello TI support
Please help me to understand what is wrong in my schema/ connection.I can't set SN74AVC4T245PWR to sleep mode and get 5uAThe left side of 1V8 come from, stand alone LDO the managed by LTE modem, once LTE modem ready to work it turn ON LDO 1V8.The right side of 3V3 connected always. always under 3V3 power.CS managed from CPU, on sleep mode Q2 is not connected and pin 15 and 14 tying to 3V3.My device should work from buttery and power consummation is my issues.When a SN74AVC4T245PWR is set as I wrote above i got total current consummation 1.2mA.when i remove two units U5 and U4 from board the current reduced to 0.2mAI set a pins of UARTs that going to controller as Analog inputs.LTE modem U1 under shut down modeWhat i am doing wrong? please advise. I need insert two devices U5 and U4 to sleep modeThank youIlya
The I/O pins must not float. (The input buffers on the powered side are always active.)
Ensure that all 3.3 V I/Os have (weak) pull-up or pull-down resistors.
Or just use the SN74AXT4T245, which has integrated 100 kΩ ull-downs.
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In reply to Clemens Ladisch:
Tank you for suggestion, i will check ..... again
Unfortunately i not found your alternative suggestion - SN74AXT4T245.
maybe you made a mistake in Part Number ?
In reply to Ilya Feldman:
Clemens was referring to the SN74AXC4T245.
Yes, the 100 kΩ pull-downs solve the problem and device going to sleep and i got 4-5uA.
Now :) i have a problem,UART side 1V8 going to CATM module. In order to insert my board to sleep mode I am shut down the CATM module. (because of that i can't configuration these pins to pull-downs)
It causes UART in float mode and SN74AVC4T245PWR not insert to sleep mode.
The SN74AXC4T245PWR is Pin-to-pin compatible with the SN74AVC4T245PWR and has the integrated 100kOhm pull-downs.
If you added 100kOhm pull-downs external to the SN74AVC4T245 - Those resistors should be too weak to impact UART performance.
In reply to Chad Crosby:
Thank you for a clear explanation and suggestion, i am ordered samples
I want to learn from you :) , why there is a component SN74AVC4T245PWR without resistors ?
I think SN74AXC4T245PWR is better, has integrated 100kOhm pull-downs. What are the pros and cons of these components
There's actually not too much different between these devices. The AXC is a newer version of the AVC device, and the AXC supports lower voltages than the AVC family.
There's no real downside to switching to the AXC device, as both are equally as fast and have the same function.
Last question :)
I not found in data sheet of AXC that it has integrated 100 kΩ pull-down
can you show me a comment of that for my learning and undertending
That feature is not listed on the datasheet, and is mostly internal knowledge.
Thank you !! for all !!!
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