The ISL88694 SMBus accelerator (SMA) is a dual active

pull-up bus terminator designed to improve data

transmission speed on SMBus or similar 2-wire serial bus

interfaces. The ISL88694 is also compatible to the I2C serial

bus.

The SMA detects rising input transitions with two internal

voltage references and two comparators per channel. After

the voltage on a data line crosses the first threshold

(VTRIPL), the boost pull-up current source is activated to

speed transition. After the voltage crosses the second

threshold (VTRIPH), the boost pull-up current source is deactivated, leaving an active pull-up current of 275µA on the

line. When both channels are HIGH, the pull-up current for

both lines is reduced to 100µA to save power. Internal logic

ensures that the active and boost pull-up current sources are

not activated during downward transitions.

The level for VTRIPH is controlled by a bandgap voltage

referred to VDD. This feature makes the switching behavior

invariant for all power supply voltages between 2.7V and

5.5V.

A noise filter on each channel prevents the circuit from

responding to input transitions that do not exceed a voltagetime threshold. To activate the boost circuit, the input must

exceed VTRIPL by 100Vns (typical) (See Figure 10).

The SMA permits operation of the bus at frequencies up to

100kHz, despite the capacitive loads of multiple devices

and/or long PC board traces. Enhanced ESD protection on

the accelerator pins are guaranteed to withstand 8kV ESD

(HBM) events.

The SMBus Accelerator provides an essential function in

SMBus applications because of distributed capacitance of

SMBus and multiple device input capacitances at various

nodes. By incorporating SMA, systems using SMBus or I2C

can reliably increase their bus load without the risk of data

loss.

Features

• Active Termination for SMBus lines

• Enhances System Bus Signal Rise Time

• Increases Bus Capacity While Guaranteeing Data Integrity

• 2.2mA Rise Time Supply Current

• 8kV ESD Protection on SDA and SCL Pins

• Wide Operating Voltage Range: 2.7V to 5.5V

• 2-Wire SMBus and I2C Compatible (100kHz)

• Small Package - SOT23-5

• Pin-for-Pin Compatible with the LTC1694

• Pb-Free Available (RoHS Compliant)

Target Applications

• Servers

• Data Acquisition

• Routers

• Battery Chargers

• Portable Instrumentation

• Notebook

• PC

• Facilities Tracking System