LPC MicrocontrollersのトピックLPC54xxx: Physical type of internal boot-ROM.

LPC54xxx: Physical type of internal boot-ROM.

jcxz — Fri, 12 Jun 2026 08:16:19 GMT

What physical type of internal boot ROM is used in the LPC54005JBD100 or LPC54S005JBD100 (and other LPC54xxx)?

Is it mask ROM? Or flash memory with write/erase functions disabled?

Is it possible to load firmware into this microcontrollers from external SPI-MRAM memory (ex. MR25H40)?
(memory located on the SPIFI or on the SPI bus). Or similar memories (FRAM, FeRAM (ex. MB85RS4MT). Insteed of FLASH.

PS: This information is needed to select the appropriate MCU for a new device.

Re: LPC54xxx: Physical type of internal boot-ROM.

Alice_Yang — Mon, 15 Jun 2026 04:02:05 GMT

Hello @jcxz

I’m not completely certain about the physical implementation of the boot ROM. However, I can confirm that it is not writable or erasable.
There is no internal flash in LPC54005 and LPC54S005 devices, so the system can only boot from external memories such as SPI/SPIFI or parallel NOR flash.
By the way, if you are preparing for a new project, I highly recommend considering the MCX series MCUs. MCX Arm Cortex-M Industrial and IoT MCUs | NXP Semiconductors The LPC54xxx family is now considered legacy, while the MCX series represents NXP’s newer generation of products.

Thank you.

Alice

Re: LPC54xxx: Physical type of internal boot-ROM.

jcxz — Mon, 15 Jun 2026 08:14:46 GMT

Thank for you answer!

My question wasn't about the ability to writing or erasing ROM LPC540xx (everything is clear here). My question was about the physical implementation of ROM-cells in LPC540xx. Boot-ROM in microcontrollers can be implemented either as a mask-ROM, or as flash-memory with disabled write/erase (or in some other way).
I also know that microcontroller's manufacturers often implement boot-ROM based on flash-memory (physically = flash-cells), but with write-protected firmware. This flash-memory is programmed with firmware into the microcontroller during manufacturing.

What is mask-ROM I mean:
Mask ROM is a type of non-volatile read-only memory where data is physically hardcoded into the microchip during the semiconductor manufacturing process. Instead of being written electronically, the data (1s and 0s) is defined by the presence or absence of microscopic transistors or connections on the chip's photomasks.

Which of these boot-ROM types (ROM-cells) is used in microcontrollers LPC540xx?
Is there any documentation (or application note) about the boot-ROM-memory type in LPC540xx?

The "MCX series MCUs" you recommended aren't suitable for our project according to the requirements specifications, as they contain flash memory.
Besides these MCUs, we're also considering the i.MX RT1020 or LPC4370. What type of memory do they have? The LPC4370 and i.MX RT1020 are somewhat overkill for our needs. LPC540xx are preferable for us.
What do you mean "legacy"? They're not marked as "NRND" on the NXP website.