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LowBit

(Logic0)

HighBit

(Logic1)

t

Low

t

High

t

LOW

t

High

EasyScaleTiming,withoutacknowledgeRFA =0

DA7

0

t

Start

StaticHigh

StaticHigh

DATA IN

t

Start

T

EOS

T

EOS

DA0

0

RFA

0

D0

1

AddressByte

DATA Byte

EasyScaleTiming,withacknowledgeRFA =1

StaticHigh

t

ACKN

Acknowledge

true,DataLine

pulleddownby

device

DATA IN

DATA OUT

Acknowledge

false,nopull

down

Controllerneedsto

PullupDataLineviaa

resistortodetect ACKN

ACKN

DA7

0

StaticHigh

T

EOS

t

valACK

DA0

0

RFA

1

D0

1

t

Start

t

Start

AddressByte

DATA Byte

TPS61170

SLVS789 – NOVEMBER 2007

Table 2. EasyScale™ Bit Description (continued)

BIT

TRANSMISSION

BYTE

NAME

DESCRIPTION

NUMBER

DIRECTION

Acknowledge condition active 0, this condition will only be applied in case RFA bit is

set. Open drain output, Line needs to be pulled high by the host with a pullup

ACK

OUT

resistor. This feature can only be used if the master has an open drain output stage.

In case of a push pull output stage Acknowledge condition may not be requested!

Figure 16. EasyScale™— Bit Coding

All bits are transmitted MSB first and LSB last. Figure 16 shows the protocol without acknowledge request (Bit

RFA = 0), Figure 16 with acknowledge (Bit RFA = 1) request. Prior to both bytes, device address byte and data

the bit transmission starts with the falling edge. If the CTRL pin is already at high level, no start condition is

needed prior to the device address byte. The transmission of each byte is closed with an End of Stream

12

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Product Folder Link(s): TPS61170