DS2484Q+T - 1-Wire Master I2C Bridge 8-TDFN | Maxim Integrated
N.º de pieza: DS2484Q+T ✓ Activo| Cant. | Precio unitario | Total |
|---|---|---|
| 1 | $3.43 | $3,43 |
| 10 | $3.08 | $30,80 |
| 100 | $2.75 | $275,00 |
| 500 | $2.46 | $1.230,00 |
| 1.000 | $2.18 | $2.180,00 |
DS2484Q+T Descripción general
What is a 1-Wire bridge? A 1-Wire bridge is a type of protocol conversion IC that maps a generic serial bus (here, I2C) to Maxim's proprietary 1-Wire single-wire half-duplex protocol used by devices such as iButtons, temperature sensors (DS18B20), battery monitors (DS2781), and EEPROMs (DS1990/DS2431). In the broader hierarchy, the DS2484 sits at: protocol bridge → interface IC → signal conditioning IC → integrated circuit, eliminating the software bit-banging overhead normally required of the host MCU while improving timing margins and 1-Wire signal integrity through active pullup drive.
Key features include an integrated 1-Wire strong-pullup switch capable of delivering up to 20 mA to power parasite-powered 1-Wire slaves, ±5 kV HBM ESD protection on the 1-Wire I/O line, a hardware adjustable slew rate for the 1-Wire output, sleep-mode current of less than 1 µA, and an open-drain active-low OUT output that mirrors the 1-Wire line state to the host. The I2C address is fixed at 0x30 and is selectable via the AD0 pin for use of up to two devices on the same bus.
At the architecture level the DS2484 pairs a finite-state-machine-driven 1-Wire master engine with an I2C slave controller and on-chip timing reference, allowing deterministic reset / presence / read / write command sequencing without host MCU overhead. The 2x3 TDFN with exposed pad keeps the RθJA low enough for hot environments, and a selectable CRC enable bit provides automatic CRC16 generation for the 1-Wire ROM command sequence.
Typical applications include IoT sensor hubs and edge nodes driving multiple DS18B20 temperature sensors, multi-tenant access control with iButton DS1990 readers, asset-tracking reference designs using DS2431 serial number ICs, and secure-print-cartridge / medical-identification authentication with Crypto-iButton or SHA-1 secure slaves. Battery-powered coin-cell designs benefit from the device's sub-1 µA sleep current.
When designing with this part, pay attention to the strong-pullup timing window after a Convert-T command; supplying a 4.7 kΩ external pull-up to a regulated rail rather than the 1-Wire line preserves the on-chip switch for energizing the slave in parasite-power mode. Decouple VDD with a 100 nF ceramic placed within 2 mm of pin 5.
This page synthesizes distributor pricing, pin-compatible Maxim Integrated alternatives, and practical design notes not consolidated on any single manufacturer page.
Alternativas directas para DS2484Q+T — mismo encapsulado, compatible pin a pin. Se excluyen las piezas de otro encapsulado que requieren retrabajo de la PCB.
Herramienta de comparación rápida — seleccione piezas alternativas para compararlas lado a lado:
DS2483Q+T
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
DS2480B+
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
DS2482-100+
✅ Sustitución directa📋 Alternativa de referencia (no en el catálogo)
DS2484Q+T Especificaciones
| Función | I2C-to-1-Wire bridge / 1-Wire master |
| Number of Channels | 1 |
| Supply Voltage (VDD) | 1.71 V to 5.25 V |
| I2C Clock Frequency | 0 to 400 kHz (Standard and Fast Mode) |
| I2C Address | 0x30 (AD0 pin selects 0x30 or 0x32) |
| 1-Wire Master Features | Reset, presence-detect, read/write time slots, strong pullup |
| Strong Pullup Current | 20 mA max |
| Rango de temperatura de funcionamiento | -40 C to +85 C |
| ESD Protection (HBM, 1-Wire IO) | ±5 kV |
| Encapsulado | 8-TDFN (2 mm x 3 mm) with exposed pad |
| Tipo de montaje | Surface Mount |
| Nivel MSL | 1 |
| Estado RoHS | Compliant |
| Lead-Free / Halogen-Free | Yes / Yes |
| Compatible Slaves | DS18B20, DS1990, DS2431, DS2480, DS2482-800, DS2482-100, DS2483 family |
Configuración de pines de DS2484Q+T
| Pin 1 | SDA — I2C serial data (open-drain; requires external pullup to VDD) |
| Pin 2 | SCL — I2C serial clock input |
| Pin 3 | AD0 — I2C address select; tie low for 0x30, high for 0x32 |
| Pin 4 | OW — 1-Wire data input/output (open-drain; requires 4.7 kΩ pullup) |
| Pin 5 | GND — Ground reference |
| Pin 6 | VDD — Supply voltage (1.71 V to 5.25 V); 100 nF decoupling cap |
| Pin 7 | OWP — Strong pullup output to energize parasitic-powered 1-Wire slaves |
| Pin 8 | OUT — Active-low open-drain 1-Wire activity indicator output |
Aplicaciones típicas
DS2484Q+T es adecuado para 7 aplicacións: IoT Multi-Drop Temperature Sensor Hubs, Access Control and iButton Reader Modules, Asset Tracking and Serial Number Logger, Print Cartridge and Medical Identification Authentication, Battery Monitoring with DS2781/DS2775, Industrial HVAC and Process-Control Sensor Backplanes, Coin-Cell Powered Smart Locks and BLE Beacons.
IoT Multi-Drop Temperature Sensor Hubs
The DS2484Q+T aggregates up to ~100 DS18B20 sensors on a single 1-Wire bus through its I2C-to-1-Wire bridge role. With 4.7 kΩ external pull-up and the on-chip 20 mA strong-pullup, Convert-T commands succeed across the full sensor count without host intervention, and the ±5 kV ESD on the 1-Wire IO line protects industrial outdoor cabling. Unlike bit-banging, the bridge enforces reset/presence/timing margins automatically, ensuring read integrity across long cable runs.
Recomendado
Access Control and iButton Reader Modules
The DS2484Q+T handles ROM-ID reads from Maxim iButtons such as the DS1990 in door-access readers, presenting the iButton-as-1-Wire-slave view to the host MCU. Its 1.71 V to 5.25 V supply tolerance supports both 3.3 V MCU-based reader logic and legacy 5 V reader hardware, and the active-low OUT pin can interrupt the host when a token is presented. The bridge also offers a CRC generator that catches bit errors on long probe cables in keypad-less ID applications.
Recomendado
Asset Tracking and Serial Number Logger
The DS2484Q+T pairs with DS2431 serial-number/EEPROM ICs to inventory physical assets through inventory wands and handheld scanners. Its 8-TDFN 2x3 mm footprint fits inside small wand tips, and the 1 µA sleep current extends handheld battery life between scans. Replacing the host's bit-banging routine with the bridge increases read success rate and frees the MCU core for Bluetooth/Wi-Fi uplink tasks.
Recomendado
Print Cartridge and Medical Identification Authentication
Authentication micro-modules in print cartridges, ink tanks, and disposable medical accessories use Maxim SHA-1 secure authenticators on the 1-Wire bus. The DS2484Q+T offloads the challenge-response protocol to its internal state machine, leaving the host to issue write/read command packets via I2C and read back the SHA-1 result. The device's 1.71 V minimum VDD also enables 2-cell alkaline or coin-cell powered authenticators.
Recomendado
Battery Monitoring with DS2781/DS2775
Battery-pack fuel gauging ICs such as the DS2775 and DS2781 connect to the host via 1-Wire and let the DS2484Q+T translate their coulomb-count and temperature register contents into I2C read transactions. The host's I2C interface runs to the bridge while the gauge measures cell voltage and temperature inside the battery, electrically isolated by the 1-Wire link and simplifying protection circuitry.
Recomendado
Industrial HVAC and Process-Control Sensor Backplanes
Industrial HVAC controllers and process-control PLCs deploy the DS2484Q+T to read multiplexed 1-Wire temperature and humidity probes mounted on pipework and ductwork. With ±5 kV ESD on the 1-Wire IO the bridge survives the high-energy transients that propagate from switched 24 VAC valve coils, and the -40 to +85 °C operating range suits boiler-room and outdoor panel installations.
Recomendado
Coin-Cell Powered Smart Locks and BLE Beacons
The DS2484Q+T's sub-1 µA sleep current and 1.71 V minimum VDD suit BLE-managed smart locks and beacons that read iButtons or serial-number tokens while idle for long periods. The bridge wakes the host only when a token event occurs, dramatically reducing coin-cell drain. The 8-TDFN exposed pad delivers sufficient heat dissipation for outdoor enclosures where ambient temperatures rise during summer.
Recomendado
Resumen de productos recomendados
Datos de referencia de ingeniería para DS2484Q+T — comparación, orientación de diseño e información de cumplimiento.
Guía de selección
Comparación con alternativas
| Parámetro | Este producto | DS2483Q+T | DS2480B+ | DS2482-100+ |
|---|---|---|---|---|
| Brand | Maxim Integrated | Maxim Integrated | Maxim Integrated | Maxim Integrated |
| Package | 8-TDFN (2x3) | 8-TDFN (2x3) - same | 8-TDFN (2x3) - same | 8-TDFN (2x3) - same |
| Host Interface | I2C (Standard/Fast Mode, up to 400 kHz) | I2C (100/400 kHz) | UART (9600/115200 baud) | I2C (100/400 kHz) |
| Supply Voltage Range | 1.71 V to 5.25 V | 2.7 V to 5.25 V (narrower low end) | 5.0 V typical | 1.71 V to 5.25 V |
| 1-Wire Channels | 1 | 1 | 1 | 1 (single channel variant of the 2482 family) |
| Strong Pullup Current | 20 mA max | 20 mA max | 20 mA max | 20 mA max |
| ESD Protection (HBM, 1-Wire IO) | ±5 kV | ±2 kV (lower) | ±2 kV (lower) | ±2 kV (lower) |
| Operating Temperature | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C | -40 C to +85 C |
Diferenciadores clave
- Wider low-end supply voltage, supporting 1.8 V coin-cell designs (frente a DS2483Q+T)
- Higher 1-Wire IO HBM ESD rating for industrial exposure (frente a DS2483Q+T)
- Selectable I2C address allows two bridges on a single bus (frente a DS2480B+)
Notas de diseño
Estimated worst-case VDD current: when the strong-pullup switch is on during a Convert-T command, the on-chip switch passes up to 20 mA from the OWP pin to the 1-Wire line; total VDD current remains <2 mA under normal read/write commands and <1 µA in sleep mode. Decouple VDD (pin 6) with a 100 nF X7R ceramic placed within 2 mm of the pin, and add a bulk 10 µF ceramic near the bridge if long 1-Wire cables are present to absorb the inrush.
The 8-TDFN exposed pad must be soldered to a copper pour on the top layer, stitched with thermal vias to inner ground planes. Without a proper pad solder joint the AC electrical ground reference for the 1-Wire open-drain driver becomes unstable, which can cause intermittent reset/presence failures. Keep the 1-Wire trace short on-board and isolate it from switching-power and I2C-SCL traces to avoid coupling that can be misinterpreted as a 1-Wire reset pulse.
Do not connect VDD directly to a CR2032 coin cell without a 1 µF bypass - the bridge's strong-pullup event can pull enough current from the weak cell to droop the rail below 1.71 V and reset the bridge mid-command. Use a 4.7 kΩ pull-up (not 10 kΩ) when the 1-Wire bus capacitance exceeds 5 nF; a 10 kΩ pull-up slows the rising edge and causes read timing violations under fast-mode host speeds.
Información de cumplimiento
RoHS compliant per Maxim Integrated product page; lead-free finish; MSL level 1. Not AEC-Q100 qualified - non-automotive grade.
