SA8803

Note 1: Referenced to GND. Stresses above those listed under "Absolute Maximum Ratings" may cause permanent damage to the device. This is a stress rating only and functional operation of the device at these or any other conditions above those indicated in the operation sections of this specification is not implied. Exposure to absolute
maximum rating conditions for extended periods may effect the device reliability.

The block Diagram of the SA8803 is shown in Fig. 1. A control word is clocked into the device via the DATA pin with a local clock provided to pin CLK. The control word comprises a 3-bit chip address, a 5-bit LED address and a Status (on/off) bit. Provided that the Chip Adress matches the setting on pins AD0..AD2 then the LED State Register SA8803 is addressed and the state of the selected LED is set according to the Status bit in the Control word.

The LEDs are driven by banks of Constant Current Sources SA8803 in which the value of the current in all six banks is set by a single external resistor connected between pin INTENS and VEE. The total current drained by the device and the LEDs may be fixed at six times the LED current by connecting pin CC to GND.

The status of all LEDs can be verified at any time by pulling the TEST pin low. When tis happens the contents of the LED Status Register are clocked out of the SA8803 on the pin DOUT. An additional test SA8803 feature is that al LEDs are illuminated for a short period after power up to simplify system testing.