Detailed Description

the data and configuring other operating characteristics. While reading the current/voltage registers, any changes in

measured current and voltage are ignored until the read is completed. The current/voltage register is updated for the new

measurement upon completion of the read operation.

also reads and writes control bits to/from the configuration registers. In addition, the interface supports useful SMBus

functions, including selectable Packet Error Checking (PEC). SMBus timeout is not supported which makes this SMBus

interface, compatible but not fully compliant.

SCL

SDA

STOP

START

REPEATED

START

Figure 1. I2C/SMBus Timing Diagram

Normal transactions consist of 2-byte writes and reads. However, some registers are single-byte read and one register

is 4-byte read. An additional byte will be appended when PEC is enabled. Attempting longer transactions is not

recommended. A transaction always begins with a START (S) condition followed by the slave address and the Write/

Read bit.

A 2-byte write transaction (Write Word) begins with the master generating a START condition and then transmitting the

MAX40080's slave address followed by the Write bit. The device acknowledges with an ACK (A) bit, and the master

transmits the target register, followed by another ACK from the MAX40080. The master then writes the two data bytes,

and the MAX40080 ACKs each. The master ends the transaction by generating a STOP (P) condition. Writing more bytes

(not recommended) will simply overwrite the register (e.g., DATA LOW - DATA HIGH - DATA LOW - DATA HIGH for a

4-byte write).

DIRECTION

M

BITS

7

1

8

CONTENT

SLAVE ADDRESS

A

REGISTER SELECT

1

S

1

WR

M

M

1

A

S

M

S

S

M

S

S

S

M

8

DATA BYTE [7:0]

M

1

A

S

S

M

8

DATA BYTE [15:8]

M

1

A

S

1

P

M

S

M

S

Figure 2. 2-Byte Write (Write Word)

When Packet Error Checking (PEC) is enabled, the write transaction is similar, except that the PEC byte (calculated

using SLAVE ADDRESS, REGISTER ADDRESS, DATA LOW, and DATA HIGH) is appended by the master after the

MAX40080

Precision, Fast Sample-Rate,

Digital Current-Sense Amplifier

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