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USB Low-Full-High Speed Peripherals

HeWi_2137741
New Contributor

We use the CY7C65213-32LTXI for a terminal console of a Controller with Linux.

Console is running under Windows 10.

While debugging we connect and disconnect the USB-plug multiple times.

But sometimes - after a disconnect and connect - the CY7C65213 is damaged so we have to replace the controller.

This already happend to uns multiple times.

How can we aviod damaging in the future?

Any suggestions?

Many thanks in advance

Helmut

This is the circuit diagram:

USB-interface.jpg

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1 Solution
YatheeshD_36
Moderator
Moderator

Hi Helmut

Is the VCCIO pin powered by the same internal source powering the rest of the circuit connected to the RXD and TXD pins? If yes then back powering of the USB-Serial bridge is not an issue.

Try connecting the internal power source supply after the USB-Serial bridge is connected to the USB host(every time) and check if you have the same problem.

How quick are u plugging in the USB-Serial Bridge controller to the host after plugging out the connection?

It is recommended to use a diode(ref: 1N4148) and a pull up resistor(10K) pulled to VCCIO at the RXD pin of the USB-Serial Bridge Controller to avoid back powering in the USB-Serial Bridge controller.

1. Please use the recommended values of Resistors and capacitors and place the capacitors close the USB serial Bridge controller.

2. Try avoiding quick re-plugging of USB-Serial Bridge to the USB host.

3. A voltage limiting device is recommended if the VBUS Voltage Exceeds USB-IF specification of 5.25 V to prevent damage to the USB-Serial Bridge Controller.

Best Regards

Yatheesh

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YatheeshD_36
Moderator
Moderator

Hi Helmut

Please let us know how the VCCIO pin is supplied with 3.3V and how you are able to detect the device is damaged.

Check if you are able to find any device that comes up in the device manager under Ports,USB or Other devices once the damaged device is connected.

FYI. In the circuit It is recommended to connect decoupling capacitors of 0.1uF and 4.7uF at VCC and VCCIO pin as well(refer the connections below in Fig 1 ).

Ferrite Beads should be connected at the USB to isolate the noise from the USB host and it is recommended to connect ESD protection diodes to the VBUS, USBDP and USBDM lines as shown below(Fig 2).

The reset pin can be tied to VDDD (instead of VCC) through an external resistor and to ground through an external capacitor with a minimum of 1us time constant since the Bridge Controller has an active low external reset and the pin should be held low for a minimum of 1us(refer for connection below in Fig 3.).

pastedImage_0.png pastedImage_1.png

                                                           Fig 1.

          pastedImage_3.png

                                                                       Fig 2.

                                      pastedImage_2.png

                                                                      Fig 3.

Best Regards,

Yatheesh

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HeWi_2137741
New Contributor

Many thanks to your response!

- VCCIO (= +3V3_USB) with 3.3V pin is supplied from internal power supply with 10uF / Ferrite / 10uF + 100nF filter. (See Fig. 1)

- Damage is detected by getting hot chip or even sometimes by smoke (yes!), but usually by not being recognized from the device manager any more (tested with different computers). After damage there is no correspondig USB device in the device manager. When replacing the IC, everything works fine again.

- VCC and VCCIO have 10uF / Ferrite / 10uF + 100nF filter. (See Fig. 1 and Fig. 2). "+5V_USB-ext" is supported by USB Host (=VBUS). USBDP and USBDM are protected by SN65220 (Single USB Port Transient Suppressor). But "+5V_USB-ext" (=VBUS) is not extra protected.

- Reset pin is connected to "+5V_USB-ext" (=VBUS) with 4k7 / 10k + 100nF, wich results in a time constant of 300us. (Fig. 3)

USB-interface_3,3V.jpg

                                   Fig. 1: VCCIO (3.3V)

USB-interface_VCC.jpgUSB-interface_5V.jpg

                                 Fig. 2: VCCIO and VCC

USB-interface_Reset.jpg

                                 Fig. 3: RESET

Best regards

Helmut

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YatheeshD_36
Moderator
Moderator

Hi Helmut

Is the VCCIO pin powered by the same internal source powering the rest of the circuit connected to the RXD and TXD pins? If yes then back powering of the USB-Serial bridge is not an issue.

Try connecting the internal power source supply after the USB-Serial bridge is connected to the USB host(every time) and check if you have the same problem.

How quick are u plugging in the USB-Serial Bridge controller to the host after plugging out the connection?

It is recommended to use a diode(ref: 1N4148) and a pull up resistor(10K) pulled to VCCIO at the RXD pin of the USB-Serial Bridge Controller to avoid back powering in the USB-Serial Bridge controller.

1. Please use the recommended values of Resistors and capacitors and place the capacitors close the USB serial Bridge controller.

2. Try avoiding quick re-plugging of USB-Serial Bridge to the USB host.

3. A voltage limiting device is recommended if the VBUS Voltage Exceeds USB-IF specification of 5.25 V to prevent damage to the USB-Serial Bridge Controller.

Best Regards

Yatheesh

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HeWi_2137741
New Contributor

Hi Yatheesh,

Is the VCCIO pin powered by the same internal source powering the rest of the circuit connected to the RXD and TXD pins?
If yes then back powering of the USB-Serial bridge is not an issue.

Yes, same power source.

Try connecting the internal power source supply after the USB-Serial bridge is connected to the USB host(every time) and check if you have the same problem.

I did this very often: while debugging the project I interrupt the power source for the development board multiple times while USB Port is still connected to Host.
Could this initiate my problem?

How quick are u plugging in the USB-Serial Bridge controller to the host after plugging out the connection?

Sometimes very quick - less than 1 second.

It is recommended to use a diode(ref: 1N4148) and a pull up resistor(10K) pulled to VCCIO at the RXD pin of the USB-Serial Bridge Controller to avoid back powering in the USB-Serial Bridge controller.

Is this still recommended when using the same power source for VCCIO and RXD / TXD (see your first question) ?

But still we have no protection cicuit for VBUS - could this lead to our problem?

Best regards

Helmut

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