MAX7316 Ver la hoja de datos (PDF) - Maxim Integrated

Número de pieza

componentes Descripción

Fabricante

MAX7316

10-Port I/O Expander with LED Intensity Control, Interrupt, and Hot-Insertion Protection

Maxim Integrated 

10-Port I/O Expander with LED Intensity

Control, Interrupt, and Hot-Insertion Protection

Port Inputs and Transition Detection

The input ports register reflects the incoming logic lev-

els of the port pins, regardless of whether the pin is

defined as an input or an output. Reading the input

ports register latches the current-input logic level of the

affected eight ports. Transition detection allows all

ports configured as inputs to be monitored for changes

in their logic status. The action of reading the input

ports register samples the corresponding 8 port bits’

input condition. This sample is continuously compared

with the actual input conditions. A detected change in

input condition causes the INT/O8 interrupt output to go

low, if configured as an interrupt output. The interrupt is

cleared either automatically if the changed input

returns to its original state, or when the input ports reg-

ister is read.

The INT/O8 pin can be configured as either an interrupt

output or as a 9th output port with the same static or

blink controls as the other eight ports (Table 4).

Port Output Control and LED Blinking

The blink phase 0 register sets the output logic levels of

the eight ports P0–P7 (Table 8). This register controls

the port outputs if the blink function is disabled. A

duplicate register, the blink phase 1 register, is also

used if the blink function is enabled (Table 9). In blink

mode, the port outputs can be flipped between using

the blink phase 0 register and the blink phase 1 regis-

ter using hardware control (the BLINK input) and/or

software control (the blink flip flag in the configuration

register) (Table 4).

The logic level of the BLINK input can be read back

through the blink status bit in the configuration register

(Table 4). The BLINK input, therefore, can be used as a

general-purpose logic input (GPI port) if the blink func-

tion is not required.

PWM Intensity Control

The MAX7316 includes an internal oscillator, nominally

32kHz, to generate PWM timing for LED intensity control.

PWM intensity control can be enabled on an output-by-

output basis, allowing the MAX7316 to provide any mix

of PWM LED drives and glitch-free logic outputs (Table

10). PWM can be disabled entirely, in which case all out-

put ports are static and the MAX7316 operating current

is lowest because the internal oscillator is turned off.

PWM intensity control uses a 4-bit master control and 4

bits of individual control per output (Tables 13, 14). The

4-bit master control provides 16 levels of overall intensi-

ty control, which applies to all PWM-enabled output

ports. The master control sets the maximum pulse

width from 1/15 to 15/15 of the PWM time period. The

individual settings comprise a 4-bit number further

reducing the duty cycle to be from 1/16 to 15/16 of the

time window set by the master control.

For applications requiring the same PWM setting for all

output ports, a single global PWM control can be used

instead of all the individual controls to simplify the con-

trol software and provide 240 steps of intensity control

(Tables 10 and 13).

Standby Mode

When the serial interface is idle and the PWM intensity

control is unused, the MAX7316 automatically enters

standby mode. If the PWM intensity control is used, the

operating current is slightly higher because the internal

PWM oscillator is running. When the serial interface is

active, the operating current also increases because

the MAX7316, like all I2C slaves, has to monitor every

transmission.

SDA

tLOW

tSU,DAT

tHD,DAT

tSU,STA

tHD,STA

tBUF

tSU,STO

SCL

tHIGH

tHD,STA

tR

tF

START CONDITION

REPEATED START CONDITION

STOP

START

CONDITION CONDITION

Figure 2. 2-Wire Serial Interface Timing Details

_______________________________________________________________________________________ 7

Share Link: