Teensy 4.1 - Power Up Sequence not working

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feliwall
 
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Joined: Sat Oct 15, 2022 11:57 am

Teensy 4.1 - Power Up Sequence not working

Post by feliwall »

Hello,

I ordered a Teensy 4.1 on September 9, 2022 (2917881-4693746004). When it arrived I connected it to a IMU (MPU6050) and a SBUS Receiver (2.4G 8CH Receiver PPM SBUS Output for Frsky X9D). All worked fine. I got data from the Receiver and from the IMU.
Teensy 4.1 connection scematic
Teensy 4.1 connection scematic
teensy4_1_scematic.PNG (856.84 KiB) Viewed 295 times
But after 2 days when I wanted to connect the Teensy to my PC via USB again I didn't get a connection.
After some Test I found out:
- Connecting the USB cable or the Vin pin to 5V and GND pin to GND I have 5V supply on my Teensy but no 3.3V supply.
- The LED does not light up at any time.
- I haven't measured a shortcut between GND and 5V or 3.3V
- I also found out that the Power Up Sequence isn't working as described below.

--------------------------------------------------------------------------------------------
Power Up Sequence (Measured with Multi - only with USB supply connected)
--------------------------------------------------------------------------------------------
1. VIN / VUSB Power - Incoming power arrives at the USB voltage regulator build into the IMXRT chip, and the TLV75733P regulator.
- Done: 4.78V via USB
2. USB_CAP & SNVS_IN - The USB voltage regulator turns on. VDD_USB_CAP charges up to approximately 2.5V. Because VDD_SNVS_IN is connected, the SNVS voltage regulator receives power.
- The VDD_USB_CAP only gets 0.25V. The VDD_SNVS_IN only gets 0.21V. --> So it seems that the power up sequence has an error here.
3. SNVS_CAP - The SNVS voltage regulator turns on, creating 1.1V at VDD_SNVS_CAP.
4. NVCC_PLL & VDD_HIGH_CAP - The IMXRT power management system turns on the PLL and Analog regulators, creating 1.1V at NVCC_PLL and 2.5V at VDD_HIGH_CAP.
5. ON REQUEST - Once power is stable, PMIC_ON_REQ is driven high with 1.1V to request main power. Later PMIC_ON_REQ becomes 3.3V, after the 3.3V power starts up.
6. 3.3V Power - The TLV75733P voltage regulator turns on, supplying the main 3.3V power to the entire board.
7. DCDC_PSWITCH - After 3.3V is stable for several milliseconds, the MKL02 chip drives DCDC_PSWITCH high.
8. CPU Power - The IMXRT DCDC buck converter begins producing 1.15V power for the CPU and most internal IMXRT circuitry. Later, software can adjust this voltage as needed for speeds greater than 528 MHz.
Attachments
Photo of my teensy 4.1 front
Photo of my teensy 4.1 front
teensy_front.jpg (94.64 KiB) Viewed 295 times
Photo of my teensy 4.1 back
Photo of my teensy 4.1 back
teensy_back.jpg (108.05 KiB) Viewed 295 times

User avatar
feliwall
 
Posts: 2
Joined: Sat Oct 15, 2022 11:57 am

Re: Teensy 4.1 - Power Up Sequence not working

Post by feliwall »

And my question is, if there is something I can do to fix this problem?
Or if there is nothing that can fix the CPU, do I have a warranty on my Teensy 4.1.

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michaelmeissner
 
Posts: 1821
Joined: Wed Aug 29, 2012 12:40 am

Re: Teensy 4.1 - Power Up Sequence not working

Post by michaelmeissner »

You might ask the question over at the Teensy forums at pjrc.com (which is the company that supplies the Teensy 4.1).

Assuming you bought the Teensy 4.1 from Adafruit, only they can answer the warranty question.

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