MAX6956 데이터 시트보기 (PDF) - Maxim Integrated

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MAX6956

2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or 28-Port LED Display Driver and I/O Expander

Maxim Integrated 

2-Wire-Interfaced, 2.5V to 5.5V, 20-Port or

28-Port LED Display Driver and I/O Expander

P4 TO P31

LED DRIVERS

OR GPIO

INTENSITY

TEST

CONFIGURATION

LED DRIVERS AND GPIO

SEGMENT OR

GPIO DATA

R/W

8

AD0

ADDRESS

AD1

MATCHER

7

8

PORT CHANGE

DETECTOR

INTENSITY REGISTERS

TEST REGISTER

PORT REGISTERS

MASK REGISTER

CONFIGURATION

REGISTERS

DATA CE R/W

8

MAX6956

COMMAND

REGISTER DECODE

8

DATA BYTE

COMMAND BYTE

D0 D1 D2 D3 D4 D5 D6 D7 D8 D9 D10 D11 D12 D13 D14 D15

7

7-BIT DEVICE ADDRESS R/W

SDA

SLAVE ADDRESS BYTE

SCL

TO/FROM DATA REGISTERS

DATA BYTE

TO COMMAND REGISTERS

COMMAND BYTE

Figure 1. MAX6956 Functional Diagram

Shutdown mode is temporarily overridden by the dis-

play test function.

Serial Interface

Serial Addressing

The MAX6956 operates as a slave that sends and

receives data through an I2C-compatible 2-wire inter-

face. The interface uses a serial data line (SDA) and a

serial clock line (SCL) to achieve bidirectional commu-

nication between master(s) and slave(s). A master (typ-

ically a microcontroller) initiates all data transfers to and

from the MAX6956, and generates the SCL clock that

synchronizes the data transfer (Figure 2).

The MAX6956 SDA line operates as both an input and

an open-drain output. A pullup resistor, typically 4.7kΩ,

is required on SDA. The MAX6956 SCL line operates

only as an input. A pullup resistor, typically 4.7kΩ, is

required on SCL if there are multiple masters on the 2-

wire interface, or if the master in a single-master system

has an open-drain SCL output.

Each transmission consists of a START condition

(Figure 3) sent by a master, followed by the MAX6956

7-bit slave address plus R/ W bit (Figure 6), a register

address byte, one or more data bytes, and finally a

STOP condition (Figure 3).

Start and Stop Conditions

Both SCL and SDA remain high when the interface is

not busy. A master signals the beginning of a transmis-

sion with a START (S) condition by transitioning SDA

from high to low while SCL is high. When the master

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