EM4100 (EM Marin 64-bit Read-Only) Compatible Cards & Fobs
EM4100 is the original and most widely deployed 125 kHz read-only proximity standard, using a factory-programmed 64-bit ID transmitted via Manchester-encoded ASK modulation.
The EM Microelectronic EM4100 chip established the de-facto standard for low-frequency proximity identification: a passive 64-bit ROM device operating at 125 kHz with no on-chip memory write capability, making every card's ID permanent from manufacture. Our compatible EM4100 cards and fobs are available in clamshell, ISO PVC, and key-tag form factors, pre-encoded to your facility code range, and ready for drop-in use on any reader that speaks the EM4100 protocol.
EM4100 (EM Marin 64-bit Read-Only) specifications
- Brand / OEM
- EM Microelectronic-Marin SA
- Technology
- Passive RFID proximity
- Frequency
- 125 kHz
- Chip
- EM4100 CMOS read-only IC; 64-bit laser-programmed ROM; ASK/OOK modulation; Manchester encoding; on-chip resonance capacitor, voltage limiter, and full-wave rectifier
- Bit formats
- 64-bit EM4100 protocol: 9 start bits + 40 data bits + 14 parity bits + 1 stop bit; transmitted as serial Manchester-encoded ASK
- OEM part numbers
- EM4100, TK4100 (compatible clone IC), H4100 (compatible clone IC)
Our compatible EM4100 (EM Marin 64-bit Read-Only) credentials
American Key Cards manufactures non-OEM credentials engineered to work with your existing EM Microelectronic-Marin readers — no hardware changes, encoded to your facility code and card-number range.
Can EM4100 (EM Marin 64-bit Read-Only) cards be copied?
EM4100 (EM Marin 64-bit Read-Only) is an open format, so a compatible card can be produced from your facility code and card number. We don't copy individual cards on request — we manufacture new, correctly-encoded credentials for systems you own or manage.
Factory-programmed read-only 64-bit ID — no encryption, no mutual authentication. Any 125 kHz reader or Proxmark3 can capture the UID; T5577 blanks can reproduce it in seconds. Suitable only for low-security or convenience applications. Upgrade to 13.56 MHz smart credentials for environments requiring clone resistance.
Where EM4100 (EM Marin 64-bit Read-Only) is used
- Basic door access control on EM-reader systems
- Time-and-attendance tracking
- Parking and vehicle gate access
- Gym and recreational facility entry
- Low-cost asset tracking and identification
Compatible readers
Related formats
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The HID H10301 26-bit format is the most widely deployed proximity card format in North America, used on millions of doors across commercial and residential buildings.
View compatible cardsAWID 26-Bit
AWID 26-bit is a 125 kHz proximity format outputting standard Wiegand 26-bit data (facility code 1–255, card number 1–65,535) via the AWID proprietary air interface, widely used in legacy commercial and residential access control systems.
View compatible cardsIndala FlexPass 26-Bit
Indala FlexPass 26-bit is a 125 kHz proximity card format using PSK modulation — architecturally distinct from HID Prox — with Wiegand output supporting 255 facility codes and up to 65,535 card numbers per site.
View compatible cardsEM4100 (EM Marin 64-bit Read-Only) — FAQ
What is the EM4100 chip and how does it work?
The EM4100 is a 64-bit read-only RFID IC made by EM Microelectronic-Marin. Its unique ID is laser-programmed at the factory and transmitted at 125 kHz using ASK modulation and Manchester encoding. It contains no battery — it harvests power from the reader's electromagnetic field.
Are your EM4100 cards compatible with TK4100 readers?
Yes. TK4100 is a widely-used compatible clone of the EM4100 chip and uses the identical 64-bit EM4100 protocol, so our cards work seamlessly with any EM4100 or TK4100 reader.
Can EM4100 cards be cloned?
Yes — the EM4100 transmits a fixed unencrypted 64-bit ID that can be captured by any 125 kHz RFID reader or Proxmark3 and copied onto a T5577 blank card. For this reason, EM4100 should only be used in low-security applications.