Compatibility with MAX7311

The MAX7313 is pin compatible and software compatible

with the standard register structure used by MAX7311,

PCA9535, and PCA9555. However, some MAX7311 func-

tions are not implemented in the MAX7313, and the

MAX7313’s PWM and blink functionality is not supported

in the MAX7311. Software compatibility is clearly not

100%, but the MAX7313 was designed so the subset

(omitted) features default to the same power-up behavior

as the MAX7311, PCA9535, and PCA9555, and superset

features do not use existing registers in a different way. In

practice, many applications can use the MAX7313 as a

drop-in replacement for the MAX7311.

Driving LED Loads

When driving LEDs, a resistor in series with the LED

must be used to limit the LED current to no more than

50mA. Choose the resistor value according to the fol-

lowing formula:

where:

LED (

Ω).

For example, to operate a 2.2V red LED at 14mA from a

16-Port I/O Expander with LED Intensity

Control, Interrupt, and Hot-Insertion Protection

______________________________________________________________________________________________________

21

Table 13. Master, O16 Intensity Register

REGISTER DATA

REGISTER

ADDRESS

CODE

(HEX)

D7

D6

D5

D4

D3

D2

D1

D0

MSB

LSB

MSB

LSB

MASTER AND GLOBAL INTENSITY

R/

W

MASTER INTENSITY

O16 INTENSITY

Write master and global intensity

0

Read back master and global intensity

1

M3

M2

M1

M0

G3

G2

G1

G0

Master intensity duty cycle is 0/15 (off);

internal oscillator is disabled;

all outputs will be static with no PWM

—

0000

—

—

—

—

Master intensity duty cycle is 1/15

—

0001

—

—

—

—

Master intensity duty cycle is 2/15

—

0010

—

—

—

—

Master intensity duty cycle is 3/15

—

0011

—

—

—

—

—

—

—

————

———

Master intensity duty cycle is 13/15

—

1101

—

—

—

—

Master intensity duty cycle is 14/15

—

1110

—

—

—

—

Master intensity duty cycle is 15/15 (full)

—

1111

—

—

—

—

O16 intensity duty cycle is 1/16

—

—

—

—

—

0

0

0

0

O16 intensity duty cycle is 2/16

—

—

—

—

—

0

0

0

1

O16 intensity duty cycle is 3/16

—

—

—

—

—

0

0

1

0

—

—

—

————

———

O16 intensity duty cycle is 14/16

—

—

—

—

—

1

1

0

1

O16 intensity duty cycle is 15/16

—

—

—

—

—

1

1

1

0

O16 intensity duty cycle is 16/16

(static output, no PWM)

—

0X0E

—

———

1

1

1

1