ISL54103

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The ISL54103 DDC Accelerator (DDCA) is a dual active pull-up bus terminator designed to improve data transmission speed on the DDC 2-wire serial bus interfaces. The DDCA 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 (V_TRIPL), the boost pull-up current source is activated to speed transition. After the voltage crosses the second threshold (V_TRIPH), the boost pull-up current source is de-activated, 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 V_TRIPH is controlled by a bandgap voltage referred to V_DD. 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 voltage-time threshold. To activate the boost circuit, the input must exceed V_TRIPL by 100Vns (typical) (See Figure 10). The DDCA 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 DDC Accelerator provides an essential function in DDC applications because of distributed capacitance of the DDC wires in long video cables. By incorporating DDCA, systems using DDC can reliably increase their bus load, allowing longer cables, without the risk of data corruption.