Holtek Semiconductor Inc. — 2 prefixes (MA-L)

A MAC address starting with 04:AC:44 or B8:CA:04 belongs to Holtek Semiconductor Inc., a Taiwan-based fabless chip designer, and is typically found on microcontroller-driven peripherals rather than networking gear itself — the company's own product lines center on 8-bit and 32-bit MCUs, display drivers, and USB-HID silicon.

Both prefixes resolve in the IEEE MA-L registry to the identical registrant name and identical Hsinchu Science Park address, which points to an active, ongoing allocation relationship rather than a single one-off filing. That, combined with Holtek being a real, long-standing public company, clears this entry above a bare unverifiable single-OUI shell.

Holtek was founded as a design house in Taipei in 1983, relocated to Hsinchu Science Park in 1988, and converted to a pure fabless model by 1998; it trades publicly on the Taiwan Stock Exchange. Its named product lines include 8051-based and proprietary 8-bit MCUs, ARM Cortex-M0+/M3 32-bit MCUs, LCD/LED display drivers, power-management ICs, and fingerprint-sensor modules.

Device-type evidence comes from a separate identifier space: Holtek also holds USB Vendor ID 0x1A81, registered to keyboards, optical/laser mice, and 2.4GHz wireless USB dongles, and appears in the Linux kernel's device-tree vendor-prefix list. No source ties a specific product model to either Ethernet OUI directly, so the device-class link here is vendor-level, not model-level, confirmation.

IEEE assignment

2 prefixes → Holtek Semiconductor Inc., registered Hsinchu, TW [Confirmed] — the IEEE MA-L registry 04AC44, the IEEE MA-L registry B8CA04

Registry / block size

MA-L (24-bit OUI); 2 confirmed IEEE prefixes; no matching entries found in the IEEE MA-S registry (MA-S) or the IEEE MA-M registry (MA-M) [Confirmed] — the IEEE MA-L registry, the IEEE MA-S registry, the IEEE MA-M registry

HQ / country

No.3, Creation Rd. II, Science Park, Hsinchu, TW 300 [Confirmed] — the IEEE MA-L registry 04AC44, the IEEE MA-L registry B8CA04

Company status

active, publicly traded (design house since 1983, Hsinchu since 1988, fabless since ~1998) [Likely] — https://en.wikipedia.org/wiki/Holtek

Device types

MCU-based USB peripherals — keyboards, optical/laser mice, 2.4GHz wireless USB dongles (via separate USB VID 0x1A81, not tied to either OUI directly) [Likely] — https://devicehunt.com/view/type/usb/vendor/1A81

Notable products

8-bit (8051-based and proprietary) and 32-bit (ARM Cortex-M0+/M3) microcontrollers, LCD/LED display drivers, power-management ICs, fingerprint-sensor modules [Likely] — https://en.wikipedia.org/wiki/Holtek

Verified sample prefixes (both MA-L, Holtek Semiconductor Inc.)

04:AC:44, B8:CA:04 [Confirmed] — the IEEE MA-L registry 04AC44, the IEEE MA-L registry B8CA04

Registration dates

Unknown — IEEE publishes no assignment/registration date field for OUI entries [Confirmed] — the IEEE MA-L registry

Third-party date caveat

maclookup.app displays scrape-observed "Registration Date" values (2017-10-31 for 04:AC:44, 2017-09-06 for B8:CA:04) that are database artifacts, not IEEE-published facts [Confirmed] — https://maclookup.app/vendors/holtek-semiconductor-inc

Security context

No CVE or malware/botnet association naming Holtek or its silicon found in NVD/CVE search results as of an August 2026 search [Unknown] — n/a

Vendor site

holtek.com is JS-rendered and returned no extractable first-party text in this search; company identity relies on Wikipedia and MarketScreener instead [Unknown] — https://en.wikipedia.org/wiki/Holtek

Related vendors

none found [Unknown] — n/a

Analyst note

Both prefixes are named, individually-owned Holtek blocks (not a shared IEEE base), so a MAC starting 04:AC:44 or B8:CA:04 is consistent with Holtek-made hardware; device-class confirmation comes from Holtek's separate USB-VID registration, not a source tying either OUI to a specific product model

[Likely] — https://devicehunt.com/view/type/usb/vendor/1A81, https://en.wikipedia.org/wiki/Holtek