Rainbow Electronics MAX6973 - Manual (Page 12)

MAX6972/MAX6973
Multiplexed vs. Nonmultiplexed Operation
The MAX6972/MAX6973 can double the number of
LEDs driven from 16 to 32 through multiplexing. When
multiplexing, the two outputs, MUX0 and MUX1, drive
two external pnp transistors, such as FMMTL717, used
as common-anode power switches (see Figure 5).
16-Output PWM LED Drivers
for Message Boards
12 ______________________________________________________________________________________
Y0 Y1 Y2 Y3 Y4 Y5 Y6 Y7
+5.55V
Q1 FMMTL717
(REDS)
(REDS)
(GREENS)
(GREENS)
R1
560
Ω
R2
180
Ω
C1
120pF
+5.55V
Q1 FMMTL717
R1
560
Ω
R2 180
Ω
C1 120pF
Z1 Z2 Z3 Z4 Z5 Z6 Z7 Z0
SUBFRAME 31
MUX1
16,384 CLKs
SUBFRAME 0
MUX0
16,384 CLKs
SUBFRAME 0
MUX1
16,384 CLKs
SUBFRAME 1
MUX0
16,384 CLKs
SUBFRAME 1
MUX1
16,384 CLKs
SUBFRAME 14
MUX0
16,384 CLKs
SUBFRAME 14
MUX1
16,384 CLKs
SUBFRAME 15
MUX0
16,384 CLKs
SUBFRAME 15
MUX1
16,384 CLKs
SUBFRAME 0
MUX0
16,384 CLKs
ONE COMPLETE 524,288 CLOCK CYCLE NONMUL
TIPLEXED VIDEO FRAME
MUX0 MUX1
Figure 5. MAX6973 Multiplexing Two Sets of Eight RG Pixels with a Single LED Supply and Subframe Timing