Ultra-Low-Power, I2C Isolator with

Unidirectional SCL, Extended VDD,

Idle-Bus Hot-Swap, and Low VOL

ADuM1253

19-101761; Rev 1; 5/24

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General Description

The ADuM1253 offers two open-drain channels, one

unidirectional and one bidirectional for applications,

such as I2C, that require data to be transmitted in both

directions on the same line but have a unidirectional

clock. To prevent latch-up action, side 1 outputs

comprise special buffers that regulate the logic-low

voltage at 0.64V, and the input logic-low threshold is at

least 50mV lower than the output logic-low voltage. Side

2 features conventional buffers that do not regulate

logic-low output voltage.

The ADuM1253 features independent 1.71V to 5.5V

supplies on both side 1 and side 2 of the isolator. The

device operates up to 2MHz. The ultra-low standby

current of 21µA per side is ideal for battery-operated

systems.

The ADuM1253 provides a disturbance-free bus

connection for hot-plug connections on side 2 by first

precharging the bus pins and then monitoring the bus

state for either an idle bus or detection of a I2C stop

condition before connecting side 1 and side 2.

The ADuM1253 is available in both an 8-pin narrow- and

wide-body SOIC package, and in an 8-pin MSOP

package. The device is rated for operation at ambient

temperatures of -40°C to +125°C.

Key Applications

• Isolated I2C/SMBus Interface

• Battery Management Systems

• Power Over Ethernet (PoE)

• Motor Control Systems

Simplified Application Diagram

ADuM1253

SDA1

SCL1

SDA2

SCL2

VDD2

VDD1

GND2

GND1

µC

SDA

SCL

SDA

SCL

0.1µF

0.1µF

1.8V

3.3V

1nF

1nF

Benefits and Features

• Low VOL(MAX) for Greater I2C Device Compatibility

• Side 1: 0.69V

• Side 2: 0.4V

• Ultra-Low-Power Consumption for Longer Battery

Life

• 142μA (typ) per Channel at 400kHz

• Wide Independent VDD1/VDD2 Supply Range

Supports More Logic Voltage Levels and Allows

Level Shifting

• 1.71V to 5.5V for Both Sides

• Hot-Swappable Side 2 I/O Prevents Data Corruption

• Initial Side 2 Connection Occurs at Bus Idle or

Stop States

• Bidirectional I2C Transfer up to 2MHz SCL

• Strong Current Sinking Enables Lower RPULL-UP

Values for Faster Bus Speeds

• Side 1: 5mA

• Side 2: 50mA

• Robust Galvanic Isolation of Digital Signals

• Continuously Withstands (VIOWM)

- 8-MSOP: 300 VRMS

- 8-Narrow SOIC: 445VRMS

- 8-Wide SOIC: 848 VRMS

• Withstands ±10kV Surge per IEC 61000-4-5

• 3 Package with Creepage and Clearance

- 8-MSOP: 3mm

- 8-Narrow SOIC: 4mm

- 8-Wide SOIC: 8mm

• Safety and Regulatory Approvals (Pending)

• IEC 60747-17 (Pending)

- Reinforced VIORM Narrow SOIC: 630VPEAK

- Reinforced VIORM Wide SOIC: 1200VPEAK

• UL 1577 (Pending)

- 8-Narrow SOIC: 3000 VRMS for 1min

- 8-Wide SOIC: 5000 VRMS for 1min

• IEC/EN/CSA 62368-1 (Pending)

• IEC/EN/CSA 61010-1 (Pending)

• CAN/CSA-C22.2 No. 14–18 (Pending)

Ordering Information appears at end of data sheet.