TCA6507_10 Datasheet, PDF (24/32 Pages) Texas Instruments – LOW-VOLTAGE 7-BIT I2C AND SMBus LED DRIVER WITH INTENSITY CONTROL AND SHUTDOWN

TCA6507
LOW-VOLTAGE 7-BIT I²C AND SMBus LED DRIVER
WITH INTENSITY CONTROL AND SHUTDOWN
SCPS164B – MAY 2007 – REVISED NOVEMBER 2007
www.ti.com
A command byte of 0001 0000 writes first to the Select0 register. Data written is 0000 0010. Since
auto-increment is enabled, the next data byte goes into Select1 and Select2 registers, respectively (see
Table 21).
Select0
Select1
Select2
Output or
LED affected
MSB
X
X
X
X
X
Table 21. LED Operation Example
0
0
0
P6
7th LED
0
0
0
P5
6th LED
0
0
0
P4
5th LED
0
0
0
P3
4th LED
0
0
0
P2
3rd LED
1
1
1
P1
2nd LED
LSB
0
0
0
P0
1st LED
For P1 or the second LED, the combination of 1 for the Select0 register (Bit 1), 1 for the Select1 register bit (bit
1), and 1 for the Select2 register bit (bit 1) puts the LED in a state where it blinks with intensity characteristic of
BANK1 (PWM1) (see Table 4).
Blink Control
The Fade-On time, Fully-On time, Fade-Off time, First Fully-Off time, and Second Fully-Off time registers must
be written to for basic blink control. Each of these registers has eight bits – top four bits for BANK1 (or PWM1)
and bottom four bits for BANK0 (or PWM0) (see Table 17).
Each BANK or PWM has a default value of 4 (0100), which translates to a time of 256 ms. The largest value for
each BANK or PWM is 15 (1111), which translates to a time of 16320 ms (see Figure 7 and Table 15).
Example of Blink Control
Starting with a powerup/reset and all seven LEDs off, here is an example (using auto-increment):
<start>, …, <command with auto-increment>, <data>, <data>, <data>, <data>, <data>, <data>, <data>, <data>, <stop>
Start, 0001 0000, 0X02, 0X02, 0X02, 0011 0000, 0101 0000, 0011 0000, 0110 0000, 1000 0000, Stop
A value of 3 is written into BANK1 in the
Fade-On Time register.
0011 in BANK1 = 192 ms in Fade-On time
A value of 5 is written into BANK1 in the
Fully-On Time register.
0101 in BANK1 = 384 ms in fully-on time
A value of 8 is written into BANK1 in the second
Fully-Off Time register.
1000 in BANK1 = 1024 ms in fully-off time (second)
A value of 6 is written into BANK1 in the First
Fully-Off time register.
0110 in BANK1 = 512 ms in fully-off time (first)
A value of 3 is written into BANK1 in the
Fade-Off Time register.
0011 in BANK1 = 192 ms in fade-off time
This sets the blink cycle as such for PWM1 or BANK1:
384ms
512ms
384ms
1024ms
192ms
192ms
192ms
192ms
24
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