MCP3426 datasheet(21/56 Pages) MICROCHIP

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DS22226A-page 21

MCP3426/7/8

TABLE 5-3:

ADDRESS BITS VS. ADDRESS

SELECTION PINS FOR

(MCP3427 AND MCP3428

ONLY) (NOTE1,2,3)

5.3.3

WRITING A CONFIGURATION BYTE

TO THE DEVICE

When the Master sends an address byte with the R/W

bit low (R/W = 0), the device expects one configuration

byte following the address. Any byte sent after this

second byte will be ignored. The user can change the

operating

mode

the

device

writing

the

configuration register bits.

If the device receives a write command with a new

configuration setting, the device immediately begins a

new conversion and updates the conversion data.

FIGURE 5-3:

Timing Diagram For Writing To The MCP3426/7/8.

I2C Device

Address Bits

Logic Status of Address

Selection Pins

Adr0 Pin

Adr1 Pin

000

0 (Addr_Low)

001

0 (Addr_Low)

Float

010

0 (Addr_Low)

1 (Addr_High)

100

1 (Addr_High)

0 (Addr_Low)

101

1 (Addr_High)

Float

110

1 (Addr_High)

011

Float

0 (Addr_Low)

111

Float

1 (Addr_High)

000

Float

Note 1:

Float: (a) Leave pin without connecting to

anything (left floating), or (b) apply

Addr_Float voltage.

The user can tie the pins to VSS or VDD:

- Tie to VSS for Addr_Low

- Tie to VDD for Addr_High

See Addr_Low, Addr_High, and

Addr_Float parameters in Electrical

Characteristics Table.

Stop Bit by

1A2 A1 A0

R/W

ACK by

MCP3426/7/8

RDY

C1 C0

O/C

S1 S0 G1 G0

1st Byte:

2nd Byte:

Master

ACK by

MCP3426/7/8

Address Byte

Configuration Byte

Start Bit by

Master

with Write command

Note:

– Stop bit can be issued any time during writing.

– MCP3426/7/8 device code is 1101 (programmed at the factory).

– See Figure 5-1 for details in Address Byte.

SCL

SDA

(a) One-Shot Mode: 1

(b) Continuous Mode: not effected

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