Microchip Technology MCP3422EV Data Sheet

© 2009 Microchip Technology Inc.

DS22088C-page 21

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 of the device by 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. 

 

0

0

0

0 (Addr_Low)

0 (Addr_Low)

0

0

1

0 (Addr_Low)

Float

0

1

0

0 (Addr_Low)

1 (Addr_High)

1

0

0

1 (Addr_High)

0 (Addr_Low)

1

0

1

1 (Addr_High)

Float

1

1

0

1 (Addr_High)

1 (Addr_High)

0

1

1

Float 0 

(Addr_Low)

1

1

1

Float

1 (Addr_High)

0

0

0

Float

Float

Float: (a) Leave pin without connecting to 
anything (left floating), or (b) apply 
Addr_Float voltage.

The user can tie the pins to V

SS

 or V

DD

:

- Tie to V

SS

 for Addr_Low

- Tie to V

DD

 for Addr_High

See Addr_Low, Addr_High, and 
Addr_Float parameters in Electrical 
Characteristics Table.

9

1

9

1

Stop Bit by

1

1

0

1

A2 A1 A0

R/W

ACK by

RDY

C1 C0

O/C

S1 S0 G1 G0

1st Byte:

2nd Byte: 

Master 

ACK by

 Address Byte 

Configuration Byte 

Start Bit by

Master 

    with Write command

– Stop bit can be issued any time during writing. 
– MCP3422/3/4 device code is 1101 (programmed at the factory).
– See 

 for details in Address Byte. 

SCL

SDA

(a) One-Shot Mode: 1

(b) Continuous Mode: not effected