DESCRIPTION

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 is addressed and the state of the selected LED is set according to the Status bit in the Control word.

FEATURES

■ Drives 24 LEDs under control of Serial Interface

■ Light Emitting Diode intensity programmable using a single resistor

■ Automatic lamp test facility on reset (MRST)

■ Minimal external components

■ LED intensity constant, regardless of

■umber of LEDs illuminated

■ 11 Bit Information word controls up to 192 LEDs (using eight SA8803s)

■ Readback of LED status

■ Requires a local clock of 8 times the data rate

■ Constant current from power supply option