TM1990A iButton Master Access Control Card Readers
The TM1990A is a CMOS electronic key device that contains a unique 64-bit digital code stored in internal nonvolatile memory. Communication with the device is performed through the 1-Wire protocol, requiring only a DATA line and a common GND connection. The device supports ROM search functionality, allowing multiple TM1990A devices to share the same 1-Wire bus.
During operation, a master controller initializes the 1-Wire bus and communicates with the TM1990A using ROM function commands. The device can provide its group code, unique 48-bit serial number, and 8-bit CRC, making it suitable for electronic identification and access-control applications.
Features:
- Unique electronic identification.
- Nonvolatile internal memory.
- 1-Wire communication interface.
- Requires only one data connection and common ground.
- Supports ROM search on a shared 1-Wire bus.
- Contact-based electronic key operation.
- Compatible with DS1990-type identification systems.
- Compact iButton form factor.
- Suitable for master-controlled identification systems.
Specifications:
| Parameter | Specification |
|---|---|
| Device Type | CMOS electronic key |
| Identification Code | 64-bit |
| Serial Number | 48-bit |
| Group Code | 8-bit |
| CRC | 8-bit |
| Communication Protocol | 1-Wire |
| Data Lines | 1 data line + GND |
| Memory Type | Nonvolatile |
| ROM Read Commands | 33h / 0Fh |
| ROM Search Command | F0h |
| Operating Voltage / Pull-Up | 2.8–6.0 V |
| Logic High Input | 2.2 V to Vpup + 0.3 V |
| Logic Low Input | -0.3 V to +0.8 V |
| Low-Level Output Voltage | Max. 0.4 V at 4 mA |
| Operating Temperature | -40°C to +85°C |
| Storage Temperature | -55°C to +125°C |
| Voltage at Pins Relative to GND | -0.5 to +7.0 V |
| Contact Type | Electronic key / iButton contact |
Applications:
- Access-control systems.
- Electronic door locks.
- Electronic key systems.
- User identification
- Equipment identification.
- Security systems.
- Attendance systems.
- Industrial access systems.
- Embedded identification systems.
- Multi-device 1-Wire identification networks.
Package Includes:
- 1x TM1990A iButton Master Access Control Card Readers.
