SA8803

sames SA8803 LIGHT EMITTING DIODE DRIVER FEATURES n Drives 24 LED's under control of Serial n 11 Bit Information word controls up to 192 LED's (using eight SA8803s) Interface n Light Emitting Diode intensity n Readback of LED status programmable using a single resistor n Requires a local clock of 8 times the data rate n Automatic lamp test facility on reset (MRST) n Constant current from power supply option n Minimal external components n LED intensity constant, regardless of number of LED's illuminated PIN CONNECTIONS 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 TEST addressed and the state of the selected LED LED 1 LED 2 LED 24 is set according to the Status bit in the Control LED 3 LED 23 word. LED 22 LED 4 V EE The LEDs are driven by banks of Constant V EE LED 21 Current Sources in which the value of the LED 5 SA8803 LED 20 current in all six banks is set by a single LED 6 LED 7 LED 19 external resistor connected between pin V V DD DD INTENS and VEE. The total current drained LED 8 LED 18 by the device and the LEDs may be fixed at LED 9 LED 17 six times the LED current by connecting pin CC to GND. The status of all LEDs can be verified at any DR-00593 time by pull...