The DS4550 is a 9-bit, nonvolatile (NV) I/O expander with 64 bytes of NV user memory controlled by either an I2C-compatible serial interface or an IEEE 1149.1 JTAG port. The DS4550 offers a digitally programmable alternative to hardware jumpers and mechanical switches that are being used to control digital logic nodes. Each I/O pin is independently configurable. The outputs are open drain with selectable pullups. Each output has the ability to sink up to 16mA, and since the device is NV, it powers up in the desired state allowing it to control digital logic inputs immediately on power- up without having to wait for the host CPU to initiate control.
The DS4550 is a 9‑bit, non‑volatile I/O expander that can be controlled via an I²C‑compatible serial interface or an IEEE 1149.1 JTAG port. Each of the nine I/O pins is independently configurable, open‑drain with selectable pull‑ups, and can sink up to 16 mA. The device includes 64 bytes of non‑volatile EEPROM user memory and supports up to eight devices on the same bus.
The datasheet provides absolute maximum ratings, recommended operating conditions, detailed pin descriptions, memory map, and typical electrical characteristics for both I²C and JTAG operation. It also outlines application examples such as FPGA bank switching, boot‑flash selection, and ASIC configuration.
| Supply Voltage | 2.7 V to 5.5 V |
|---|---|
| Operating Temperature Range | -40 °C to +85 °C |
| Output Sink Current | 16 mA per I/O pin |
| User EEPROM Size | 64 bytes |
| Number of I/O Pins | 9 (nine NV inputs/outputs) |
| Maximum Multidrop Devices | 8 devices on the same bus |
| I²C Clock Frequency | up to 400 kHz |
| I/O Pull‑up Resistor Values | 40 kΩ to 75 kΩ |
The device operates from 2.7 V up to 5.5 V.
Up to eight DS4550 devices can share the same I²C or JTAG bus.
Each output can sink up to 16 mA.
The DS4550 provides 64 bytes of non‑volatile EEPROM user memory.