CAT9552WI Datasheet, PDF (9/17 Pages) ON Semiconductor – 16-Channel I2C-bus LED Driver with Programmable Blink Rate

CAT9552
Input Register 0 and Input Register 1 reflect the
incoming logic levels of the I/O pins, regardless of
whether the pin is defined as an input or an output.
These registers are read only ports. Writes to the input
registers will be acknowledged but will have no effect.
Table 2. Input Register 0 and Input Register 1
INPUT0
LED LED LED LED LED LED LED LED
7
6
5
4
3
2
1
0
bit
7
6
5
4
3
2
1
0
default X
XXX
X
X
X
X
INPUT1
LED LED LED LED LED LED LED LED
15 14 13 12 11 10 9
8
bit
7
6
5
4
3
2
1
0
default X
XXX
X
X
X
X
The Frequency Prescaler 0 and Frequency Prescaler
1 registers (PSC0, PSC1) are used to program the
period of the pulse width modulated signals BLINK0
and BLINK1 respectively:
T_BLINK0 = (PSC0 + 1) / 44;
T_BLINK1 = (PSC1 + 1) / 44
Table 3. Frequency Prescaler 0 and Frequency
Prescaler 1 Registers
PSC0
bit
7
6
5
4
3
2
1
0
default 1
1
1
1
1
1
1
1
PSC1
bit
7
6
5
4
3
2
1
0
default 1
1
1
1
1
1
1
1
The PWM Register 0 and PWM Register 1 (PWM0,
PWM1) are used to program the duty cycle of BLINK0
and BLINK1 respectively:
Duty Cycle_BLINK0 = (256 - PWM0) / 256;
Duty Cycle_BLINK1 = (256 - PWM1) / 256
After writing to the PWM0/1 register an 8-bit internal
counter starts to count from 0 to 255. The outputs are
low (LED on) when the counter value is less than the
value programmed into PWM register. The LED is off
when the counter value is higher than the value written
into PWM register.
Table 4. PWM Register 0 and PWM Register 1
PWM0
bit
7
6
5
4
3
2
1
0
default 1
0
0
0
0
0
0
0
PWM1
bit
7
6
5
4
3
2
1
0
default 1
0
0
0
0
0
0
0
Every LED driver output can be programmed to one of
four states, LED OFF, LED ON, LED blinks at BLINK0
rate and LED blinks at BLINK1 rate using the LED
Selector Registers (Table 5).
Table 5. LED Selector Registers
LS0
bit
default
LED 3
7
6
0
0
LED 2
5
4
0
0
LED 1
3
2
0
0
LED 0
1
0
0
0
LS1
bit
default
LED 7
7
6
0
0
LED 6
5
4
0
0
LED 5
3
2
0
0
LED 4
1
0
0
0
LS2
bit
default
LED 11
7
6
0
0
LED 10
5
4
0
0
LED 9
3
2
0
0
LED 8
1
0
0
0
LS3
bit
default
LED 15
7
6
0
0
LED 14
5
4
0
0
LED 13
3
2
0
0
LED 12
1
0
0
0
The LED output (LED0 to LED15) is set by the 2 bit
value from the corresponding LSx Register (x = 0 to 3):
00 = LED Output set LOW (LED On)
01 = LED Output set Hi-Z (LED Off – Default)
10 = LED Output blinks at BLINK0 Rate
11 = LED Output blinks at BLINK1 Rate
© 2008 SCILLC. All rights reserved
9
Characteristics subject to change without notice
Doc. No. MD-9005 Rev B