16-Port I/O Expander with LED Intensity

Control, Interrupt, and Hot-Insertion Protection

18

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Table 10. PWM Application Scenarios

APPLICATION

RECOMMENDED CONFIGURATION

All outputs static without PWM

Set the master, O16 intensity register 0x0E to any value 0x00 to 0x0F.

The global intensity G bit in the configuration register is don't care.

The output intensity registers 0x10 through 0x17 are don't care.

A mix of static and PWM outputs, with PWM

outputs using different PWM settings

Set the master, O16 intensity register 0x0E to any value from 0x10 to 0xFF.

Clear global intensity G bit to 0 in the configuration register to disable global intensity

control.

For the static outputs, set the output intensity value to 0xF.

For the PWM outputs, set the output intensity value in the range 0x0 to 0xE.

A mix of static and PWM outputs, with PWM

outputs all using the same PWM setting

As above. Global intensity control cannot be used with a mix of static and PWM

outputs, so write the individual intensity registers with the same PWM value.

All outputs PWM using the same PWM

setting

Set the master, O16 intensity register 0x0E to any value except from 0x10 to 0xFF.

Set global intensity G bit to 1 in the configuration register to enable global intensity

control.

The master, O16 intensity register 0x0E is the only intensity register used.

The output intensity registers 0x10 through 0x17 are don't care.

Figure 11. PWM Timing

ONE PWM PERIOD IS 240 CYCLES OF THE 32kHz PWM

OSCILLATOR. A PWM PERIOD CONTAINS 15 MASTER

INTENSITY TIMESLOTS

1

2

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15

1

2

EACH MASTER INTENSITY

TIMESLOT CONTAINS 16

PWM CYCLES

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8

9

10 11 12 13 14 15 16

15 16

1

2

Figure 12. Master Set to 1/15

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Figure 14. Master Set to 15/15

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Figure 13. Master Set to 14/15

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9 10 11 12 13 14

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