The EM4425, marketed as em|echo-V, is the dual-frequency chip from the Swiss manufacturer EM Microelectronic (a Swatch Group company): it brings together on a single die an NFC and HF interface (ISO/IEC 15693, NFC Forum Type 5) and a UHF RAIN RFID interface (EPC Gen2v2, ISO/IEC 18000-63), which share the same memory and the same identifier. A single tag thus accompanies the product's whole life: long-range logistics inventory on the UHF side, smartphone interaction on the NFC side (authenticity, product information, consumer engagement), from the factory to the end customer. EM calls this concept RAINFC; NFC reading works with the vast majority of recent smartphones.
Information
| Manufacturer | EM Microelectronic |
| Family | em|echo (RAINFC) |
| Reference | EM4425 (em|echo-V) |
| Standards | ISO/IEC 15693 (HF); EPC Gen2v2 and ISO/IEC 18000-63 (UHF) |
| NFC Forum type | Type 5 Tag |
| Operating frequencies | 13.56 MHz and 860 to 960 MHz |
| Identifiers | 8-byte UID (HF) and 96-bit TID (UHF), on a single chip |
| Tuning capacitance | 50 pF (HF interface) |
| Operating distance | Several meters in UHF with a RAIN reader; a few centimeters in NFC with a smartphone |
| Data retention | 50 years |
| Write endurance | 100,000 cycles |
| Memory | 256 shared bytes (2,048 bits), plus 480 bits of EPC |
Memory
The memory of the EM4425 is the heart of its concept: the NFC, HF and UHF interfaces read and write the same data, under a common identifier:
| Area | Content | Access |
|---|---|---|
| Shared user memory | 256 bytes accessible through the NFC, HF and UHF interfaces | Read / write from both sides; NDEF message on the NFC side |
| EPC memory (UHF) | 480 bits for the electronic product code of logistics | Read and inventoried by RAIN readers |
| Identifiers and configuration | 8-byte HF UID, 96-bit UHF TID, versions and security options | Set at the factory or managed through dedicated commands |
Used as a Type 5 NFC tag, the shared memory hosts an NDEF record representing a URL of around 240 characters, with the data remaining visible to the logistics chain on the UHF side. A tamper loop, connected to the chip's Tamper pins, furthermore lets equipped labels signal their opening.
Features & security
- Two radios, one chip: NFC for smartphone proximity, HF for the vicinity of ISO 15693 readers and UHF RAIN for long range live on a single die: one tag, encoded in a single pass, replaces both the logistics label and the consumer label.
- Shared memory and identity: all interfaces see the same data and the same serial number, the bridge between supply-chain processes and the customer experience.
- Web Authentication: depending on the version, the chip composes a dynamic web authentication verifiable online at tap time (brand protection without a dedicated app), with the AES option compliant with ISO/IEC 29167-10 adding cryptographic authentication.
- Tamper detection: the conductive loop connected to the dedicated pins signals to the reader the opening of a sealed label or package.
- Gen2v2 standards on the UHF side: 480-bit EPC, 96-bit TID and the standard's 32-bit access and kill passwords, for massive inventory at several meters and end-of-life deactivation.
- Versions à la carte: seven versions (V10 to V16) decline the radio interface (dual frequency or NFC only) and the HF security (none, Web Authentication, or Web Authentication with AES), to match the chip to the application's exact needs.
Data retention reaches 50 years for 100,000 write cycles, and the HF interface tunes at 50 pF. The targeted segments range from retail to aerospace, through product authentication, industry and automotive.
Compatibility
On the NFC side, the EM4425 uses NFC-V technology (ISO/IEC 15693), supported by the vast majority of recent NFC smartphones. On Android (version 9.0 or later according to EM), reading and writing work natively with NFC Tools. On iPhone, automatic background reading is available from the iPhone XS and XR onwards; models from the iPhone 7 can read and write the chip via NFC Tools on iOS 15.6 or later, by starting the scan manually from the app.
With NFC Tools, the EM4425 chip supports reading technical information, writing records, erasing and locking. The UHF interface, invisible to smartphones, is read by the RAIN RFID readers of the logistics chain, and the web authentication or AES features depend on the dedicated versions and infrastructures. The list of compatible models is available in the article on compatibility.
EM4425 vs EM4237
| Chip | User memory | Strengths | Positioning |
|---|---|---|---|
| EM4425 (em|echo-V) | 256 shared bytes, plus the EPC | NFC and UHF combined, Web Authentication, tamper | One tag from logistics to the consumer |
| EM4237SLIC / SLIX | 128 or 256 bytes | HF only: password, customizable EAS, privacy, destroy | Libraries and asset management |
The question that separates the two families is simple: does the tag need to exist in the UHF world of logistics? If so, the em|echo-V replaces two labels with one; if not, the EM4237SLIC and SLIX offer the most complete HF arsenal. On the NXP and STMicroelectronics side, the ICODE and ST25TV remain the single-frequency vicinity references, and the NTAG213 the consumer tag reference.
Frequently asked questions
How much data can be stored on an EM4425?
The chip offers 256 bytes of memory shared between the interfaces, i.e. a URL of around 240 characters in NDEF usage, plus 480 bits of EPC memory reserved for the product code of UHF logistics.
What is the dual frequency of the em|echo-V for?
Making a single tag live across the whole chain: RAIN UHF readers inventory products by entire boxes at several meters (warehouses, gates), then the same tag answers the customer's smartphone in NFC (authenticity, information, engagement). Both worlds see the same data and the same identifier, without double labeling.
Is the EM4425 compatible with iPhones?
Yes, on the NFC side: background reading works from the iPhone XS and XR onwards, and both reading and writing are possible via NFC Tools from the iPhone 7 on iOS 15.6 or later. The UHF interface requires dedicated RAIN readers.
Can an EM4425 be protected against rewriting?
Yes: on the NFC side, locking follows the Type 5 mechanisms, including from NFC Tools; on the UHF side, the standard's 32-bit access and kill passwords protect the memory and allow permanent deactivation; some versions add AES authentication.
