topic Re: LPC2468FBD208 revB failed ICT in LPC Microcontrollers

LPC2468FBD208 revB failed ICT

rdte — Thu, 07 Jan 2021 08:57:22 GMT

Hi,

Can someone help me to solve the problem I encountered during ICT ? Using rev.B of this device zener diode voltage is pulled low but when using rev.D, ICT passed. I checked the errata sheet and cannot find any information related to this.

Additional question, does rev.B and rev.D have different device ID ?

Thank you in advance for your help

Re: LPC2468FBD208 revB failed ICT

xiangjun_rong — Thu, 07 Jan 2021 09:29:39 GMT

Hi, Maria,

Can you tell us what the ICT means? regarding the zener diode voltage, I have checked the UM of lpc24xx, I do not find out any zener diode, do you use external zener diode?

XiangJun Rong

Re: LPC2468FBD208 revB failed ICT

rdte — Thu, 07 Jan 2021 09:36:40 GMT

ICT is in-circuit testing. Yes, external zener diode.

Re: LPC2468FBD208 revB failed ICT

xiangjun_rong — Fri, 08 Jan 2021 08:08:36 GMT

Hi, Maria,

For the zener diode, generally it' cathode is connected to a serial resistor, then a power supply, it's anode is connected to GND, in the condition, the zener diode can output a constant voltage. How do you connect the zener diode to LPC2468?

Regarding ICT, do you use boundary scan tools to test the internal circuit?

XiangJun rong

Re: LPC2468FBD208 revB failed ICT

rdte — Thu, 14 Jan 2021 07:20:53 GMT

Hi xinagjun,

The zener diode is connected to a serial resistor. Zener is used to protect pin 18 of LPC2468FBD208, in case a high voltage (transient) is present at P1-10 and P1-9. Zener is connected to pin 18.

On boundary scan. yes, we use boundary scan tools to test the internal circuit but fails with an error in the internal ID code.

Thank you in advance for your support.

Regards,

Maria

Re: LPC2468FBD208 revB failed ICT

xiangjun_rong — Wed, 20 Jan 2021 03:21:20 GMT

Hi,

I suppose that you connect the GPIO pin to the cathode pin of zener node, in the case, the GPIO pin voltage is clamped to a fixed voltage, if the ICT tools set the GPIO pin in input mode, no problem. But if the ICT tools set the GPIO pin in output mode, there is issue.

XiangJun Rong