DS2741N Просмотр технического описания (PDF) - Maxim Integrated

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DS2741N

Current Monitor and Accumulator with Integrated Sense Resistor

Maxim Integrated 

Current Monitor and Accumulator with

Integrated Sense Resistor

COMMUNICATIONS KEY

S START A ACK

WHITE BOXES INDICATE THE MASTER IS

CONTROLLING SDA

P STOP N NACK

SHADED BOXES INDICATE THE SLAVE IS

CONTROLLING SDA

SR

REPEATED

START

X X X X X X X X 8-BIT ADDRESS OR DATA

WRITE TWO BYTES WITH A SINGLE TRANSACTION TO SLAVE ADRESS 68h

S 0 1 1 0 1 0 0 0 A MEMORY ADDRESS A

DATA

NOTES

1) ALL BYTES ARE SENT MOST SIGNIFICANT BIT FIRST.

2) THE FIRST BYTE SENT AFTER A START CONDITION

IS ALWAYS THE SLAVE ADDRESS FOLLOWED BY

THE READ/WRITE BIT.

A

DATA

AP

READ A SINGLE BYTE WITH A DUMMY WRITE CYCLE TO SET THE ADDRESS COUNTER FROM SLAVE ADDRESS 68h

S 0 1 1 0 1 0 0 0 A MEMORY ADDRESS A SR 0 1 1 0 1 0 0 1 A

DATA

NP

READ TWO BYTES WITH A DUMMY WRITE CYCLE TO SET THE ADDRESS COUNTER FROM SLAVE ADDRESS 68h

S 0 1 1 0 1 0 0 0 A MEMORY ADDRESS A SR 0 1 1 0 1 0 0 1 A

DATA

A

DATA

NP

Figure 6. I2C Communications Examples

ble, and generates a STOP condition. See Figure 6

for a read example using the repeated START condi-

tion to specify the starting memory location.

Reading Multiple Bytes from a Slave: The read

operation can be used to read multiple bytes with a

single transfer. When reading bytes from the slave,

the master simply ACKs the data byte if it desires to

read another byte before terminating the transaction.

After the master reads the last byte, it NACKs to

indicate the end of the transfer and generates a

STOP condition. This can be done with or without

modifying the address counter’s location before the

read cycle. The DS2741’s address counter does not

wrap on page boundaries during read operations,

but the counter rolls from its uppermost memory

address FFh to 00h if the last memory location is

read during the read transaction.

Applications Information

Power-Supply Decoupling

To achieve best results, it is recommended that the power

supply is decoupled with a 0.01µF or a 0.1µF capacitor.

Use high-quality, ceramic, surface-mount capacitors, and

mount the capacitors as close as possible to the VCC and

GND pins to minimize lead inductance.

SDA and SCL Pullup Resistors

SDA is an open-collector output on the DS2741 that

requires a pullup resistor to realize high logic levels. A

master using either an open-collector output with a

pullup resistor or a push-pull output driver can be used

for SCL. Pullup resistor values should be chosen to

ensure that the rise and fall times listed in the AC elec-

trical characteristics are within specification.

Package Information

For the latest package outline information and land patterns, go

to www.maxim-ic.com/packages.

PACKAGE TYPE PACKAGE CODE DOCUMENT NO.

14 TDFN-EP

T1433+2

21-0137

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