CAT9552 ONSEMI [ON Semiconductor], CAT9552 Datasheet - Page 9

• Manufacturer Part Number: CAT9552
• Description: 16-Channel I2C-bus LED Driver with Programmable Blink Rate
• Manufacturer: ONSEMI [ON Semiconductor]

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
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
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.
© 2010 SCILLC. All rights reserved
Characteristics subject to change without notice
INPUT0
INPUT1
PSC0
PSC1
default
default
default
default
bit
bit
bit
bit
Prescaler 1 Registers
LED
LED
15
7
7
X
7
X
7
1
7
1
LED
LED
14
6
6
X
6
X
6
1
6
1
LED
LED
13
X
X
5
5
5
5
1
5
1
LED
LED
12
X
X
4
4
4
4
1
4
1
LED
LED
11
X
X
3
3
3
3
1
3
1
LED
LED
10
2
2
X
2
X
2
1
2
1
LED
LED
X
X
1
1
9
1
1
1
1
1
LED
LED
X
X
0
1
0
1
0
0
8
0
9
Table 4. PWM Register 0 and PWM Register 1
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
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
PWM0
PWM1
LS0
LS1
LS2
LS3
default
default
default
default
default
default
bit
bit
bit
bit
bit
bit
7
0
7
0
7
0
7
0
7
1
7
1
LED 11
LED 15
LED 3
LED 7
6
1
6
1
6
1
6
1
6
0
6
0
5
0
5
0
5
0
5
0
5
0
5
0
LED 10
LED 14
LED 2
LED 6
4
1
4
1
4
1
4
1
4
0
4
0
3
0
3
0
3
0
3
0
3
0
3
0
LED 13
LED 1
LED 5
LED 9
Doc. No. MD-9005 Rev D
2
1
2
1
2
1
2
1
2
0
2
0
CAT9552
1
0
1
0
1
0
1
0
1
0
1
0
LED 12
LED 0
LED 4
LED 8
0
1
0
1
0
1
0
1
0
0
0
0