3.3V Spread-Spectrum EconOscillator

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11

Application Information

Power-Supply Decoupling

To achieve the best results when using the DS1087L,

decouple the power supply with 0.01µF and 0.1µF

high-quality, ceramic, surface-mount capacitors.

Surface-mount components minimize lead inductance,

which improves performance, and ceramic capacitors

tend to have adequate high-frequency response for

decoupling applications. These capacitors should be

Stand-alone Mode

SCL and SDA cannot be left floating even in stand-

alone mode. If the DS1087L never needs to be pro-

grammed in-circuit, including during production

testing, SDA and SCL can be wired high.

SDA

SCL

REPEATED

START

STOP

START

Figure 5. 2-Wire AC Characteristics

SLAVE

ACK

10

1

1

R/W

A0*

A1*

SLAVE

ACK

A2*

MSB

LSB

DEVICE IDENTIFIER

DEVICE

ADDRESS

READ/

WRITE

MSB

LSB

COMMAND/REGISTER ADDRESS

SLAVE

ACK

MSB

LSB

b7

b6

b5

b4

b3

b2

b1

b0

SLAVE

ACK

STOP

*THE ADDRESS DETERMINED BY A0, A1, AND A2 MUST

MATCH THE ADDRESS SET IN THE ADDR REGISTER.

DATA

TYPICAL 2-WIRE WRITE TRANSACTION

EXAMPLE 2-WIRE TRANSACTIONS (WHEN A0, A1, AND A2 ARE ZERO)

A) SINGLE BYTE WRITE

-WRITE PRESCALER

REGISTER TO 128

B) SINGLE BYTE READ

-READ PRESCALER

REGISTER

START

START

START

B0h

B0h

SLAVE

ACK

SLAVE

ACK

02h

02h

SLAVE

ACK

SLAVE

ACK

DATA

SLAVE

ACK

STOP

10110000

10110000

b7

b6

b5

b4

b3

b2

b1

b0

00000010

10000000

10000000

00000010

REPEATED

START

DATA

MASTER

NACK

STOP

SLAVE

ACK

10110001

B1h

Figure 6. 2-Wire Transactions