Implementing LED Drivers in Supported Altera Devices
When using a supported Altera device as an LED driver chip, place a current-limiting resistor between the cathode side of the LEDs diode and the supported Altera device I/O. The LEDs anode is tied to VCC , and is turned on when the device I/O drive low.
The most important aspect of an LED driver chip is the amount of current it has to sink. Many LED applications call for a current sink specification of 5 to 15 mA. Because the supported Altera devices can sink up to 50 mA per pin, these devices can directly integrate commercial current-sinking LED driver chips.
| Device | Maximum Sink Current Per Pin (mA) |
|---|---|
| MAX II | 25 1 |
| MAX V | 25 1 |
| MAX 10 | 25 1 |
| MAX 3000A | 25 |
| MAX 7000A/AE | 25 |
| MAX 7000B | 50 |
| MAX 7000S | 25 |
Although a single pin from a MAX 7000B device can sink up to 50 mA of DC current, each GNDIO group can concurrently sink up to 200 mA of current due to the support of advanced I/O standards.
| Device | Maximum Source Current Per VCCIO Group (mA) | Maximum Sink Current Per GNDIO Group (mA) |
|---|---|---|
| MAX II | 170 | 130 |
| MAX V | 170 | 130 |
| MAX 10 | 160 | 160 |
| MAX 3000A | 224 | 167 |
| MAX 7000A/AE | 224 | 167 |
| MAX 7000B | 380 | 200 |
| MAX 7000S | 244 | 160 |
For example, the EPM240 device has six GNDIO pads, which provide six I/O regions that can sink up to 130 mΑ. If you need to sink 15 mA for the outputs, you can have eight outputs per region. With the six regions of I/O between GNDIO pads, there are 48 possible outputs, each sinking 15 mA.
1 25 mA is the absolute maximum rating for the sink current per pin in the MAX II, MAX V, and MAX 10 devices. Device operation at the absolute maximum ratings for extended periods of time may have adverse effects on the device.