I2C 7seg driver

Does anyone know of any good I2C 7segment display drivers. I swear a previous answer referenced a chip for this on chiphacker but I cannot find it.

I would also be happy with SPI, but I I2C would work better as I plan to use many 7Seg.

The Maxim MAX6955 might be suitable.

• For some reason Maxim display drivers are terribly expensive. Leon rightfully remarked that the MAX6950 costs $\$$13.84, but this one is even$28(!) – stevenvh May 26 '11 at 6:29

On the simple side of things, you could use serial-to-parallel shift register chips to drive the 7 segment displays. The SPI interface can probably be set up to send out the data without any issues. It's chain-able as well.

The 74HC164 is an example of one of these chips, and with 8 outputs per chip, it would be able to drive the 7 segments plus a decimal point.

• I should have been more clear. The reason for wanting a device designed to drive a 7-seg is due to maintenance. I am going to be putting this project together for a professor and they whatever student he can get his hands on is going to have to maintain and add features. I have a feeling they may not do maintenance well or properly and having a simpler chip would be better in my eyes. – Kortuk Apr 13 '10 at 1:50
• Well, any digital output and a resistor can drive a LED. I'm assuming you have a microcontroller driving your display. You didn't give any ballpark figure on number of digits. The "hard" part is making a uC function to change a number into a byte signalling on/off LED's. The chips are very simple and easy to understand. Expansion is easy, and there's no multiplexing to worry about. The chips are fairly cheap too. – W5VO Apr 13 '10 at 4:55
• ballpark is about 2 digits, but I was interested in seeing solutions that could do more, as it is a case to increase the visual output of the project. I passed on the answers, but I was done with the project because the person I was being paid to help was taking too long. He has a different student helping him over the summer. – Kortuk Dec 12 '10 at 16:40

There are many I/O Expanders out there that use either SPI or I2C buses. With a single MSSP module you can control almost an infinite amount of digital outputs like LEDs. Depending on the current draw of the LEDs in your 7seg display you may be able to control them with an I/O expander like the MCP23008. Check the datasheets for your display and the MCP23008.