MAX6946CAWE 查看數據表（PDF） - Maxim Integrated

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MAX6946CAWE

10-Port, Constant-Current LED Driver and I/O Expander with PWM Intensity Control

Maxim Integrated 

10-Port, Constant-Current LED Driver and

I/O Expander with PWM Intensity Control

I/O Ports

The MAX6946/MAX6947 contain 10 I/O ports.

Configure the 10 I/O ports as logic inputs, open-drain

logic outputs, or constant-current sinks in any combina-

tion. Table 4 shows a detailed description of the indi-

vidual port configuration registers 0x00 through 0x09.

Use registers 0x00–0x09 to individually assign each

port as a logic input, open-drain logic output or con-

stant-current sink (see the PWM Intensity Control and

Phasing section). The I/O ports are high impedance

without VDD applied and remain high impedance upon

power-up.

Figure 1 shows the I/O port structure of the MAX6946/

MAX6947. I/O ports P0 to P9 default to high impedance

on power-up, so LEDs or other port loads connected

draw no current. Ports used as inputs do not load their

source signals.

TO/FROM

SERIAL

INTERFACE

POSITION A: 0x00–0x01

POSITION B: 0x02–0xFF

8-BIT LATCH

OUTPUT PORT

REGISTER

CLOSE SWITCH: 0x02–0xFE

PWM

GENERATOR

1-BIT LATCH

MSB

OUTPUT CURRENT

REGISTER

3-BIT LATCH

GLOBAL CURRENT

REGISTER

READ I/O

PORT COMMAND

4-BIT DAC

ENABLE

SET

CURRENT

I/O PORT

A

B

N

Figure 1. Simplified Schematic of I/O Ports

Table 4. Individual Port Configuration Options (Port Output Registers 0x00–0x09)

PORT TYPE

Low-logic

output

High-logic

output

Logic input

Constant-

current static

sink output

Constant-

current PWM

output

OUTPUT

REGISTER

CODE

RUN MODE (CONFIGURATION

REGISTER BIT D0 = 1)

SHUTDOWN

(CONFIGURATION REGISTER

BIT D0 = 0)

APPLICATION NOTES

0x00

0x01

Logic-low output, not constant current

Logic-high output with external pullup resistor;

otherwise, high impedance

CMOS logic input

Lowest supply current,

unaffected by shutdown

0x02

Static constant-current sink

output

0x03–0xFE

0x03 = 3/256 PWM duty cycle

0xFE = 254/256 PWM duty cycle

High impedance

Full constant-current drive

with no PWM

Adjustable constant current

LED off

0xFF

Logic-high output with external pullup resistor; otherwise,

high impedance

LED off

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