Integration of LED Drivers
Discrete light-emitting diode (LED) driver chips are common on system boards. Altera's MAX 7000A , MAX 7000B, and MAX 3000A devices offer unique capabilities that allow you to integrate single or multiple LED-driven chips into a single MAX device.
Implementing the LED Driver Using a MAX Device
Figure 1 shows how MAX devices can be configured as LED-driver devices. Many such driver chips are current-sinking, as opposed to current-sourcing. Current-sinking driver chips sink the DC current required to drive common-anode LEDs. The anode of these LEDs is tied to VCC and the cathodes are connected to the LED driver chip. The LED is turned on when the pins of the driver chip connected to the LED are pulled low.
Figure 1: Implementation of a LED driver using a MAX device.
The most important requirement of an LED driver chip is the amount of current it has to sink. Many LED applications call for a current sink of 5 to 15 mA. Since MAX devices can satisfy these current-sinking requirements, designers can directly integrate LED drivers into MAX devices. Table 1 shows the maximum sink current on an I/O pin for MAX devices.
| Table 1: Maximum Sink Current on MAX I/O Pin |
| Device |
Maximum Sink Current on I/O Pin
|
| MAX 7000B |
50 mA |
| MAX 7000A |
25 mA |
| MAX 7000S |
25 mA |
| MAX 3000A |
25 mA |
By choosing a MAX device with enough pin and register capabilities, a designer can integrate one or multiple LED driver chips into a single MAX device. In addition to integrating LED drivers, MAX devices can also integrate any user or control logic required on a system board, saving board space and reducing the overall system cost.
See the Implementing LED Drivers in MAX Devices White Paper for more details.
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