Datasheet
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:
R
LED
= (V
SUPPLY
- V
LED
- V
OL
) / I
LED
where:
R
LED
is the resistance of the resistor in series with the
LED (Ω).
V
SUPPLY
is the supply voltage used to drive the LED (V).
V
LED
is the forward voltage of the LED (V).
V
OL
is the output low voltage of the MAX7313 when
sinking I
LED
(V).
I
LED
is the desired operating current of the LED (A).
For example, to operate a 2.2V red LED at 14mA from a
5V supply, R
LED
= (5 - 2.2 - 0.25) / 0.014 = 182Ω.
MAX7313
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