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ADV7281

Data Sheet

Rev. A | Page 16 of 32

POWER SUPPLY SEQUENCING

OPTIMAL POWER-UP SEQUENCE

The optimal power-up sequence for the ADV7281/ADV7281-M/

ADV7281-MA is to first power up the 3.3 V DVDDIO supply,

followed by the 1.8 V supplies DVDD, PVDD, AVDD, and MVDD.

MVDD only applies to the ADV7281-M/ADV7281-MA models.

When powering up the ADV7281/ADV7281-M/ADV7281-MA,

follow these steps. During power-up, all supplies must adhere

to the specifications listed in the Absolute Maximum Ratings

section.

1. Assert the PWRDWN and RESET pins (pull the pins low).

2. Power up the DVDDIO supply.

3. After DVDDIO is fully asserted, power up the 1.8 V supplies.

4. After the 1.8 V supplies are fully asserted, pull

the PWRDWN pin high.

5. Wait 5 ms and then pull the RESET pin high.

6. After all power supplies and the PWRDWN and RESET

pins are powered up and stable, wait an additional 5 ms

before initiating I2C communication with the ADV7281/

ADV7281-M/ADV7281-MA.

SIMPLIFIED POWER-UP SEQUENCE

Alternatively, the ADV7281/ADV7281-M/ADV7281-MA can

be powered up by asserting all supplies and the PWRDWN

and RESET pins simultaneously. After this operation, perform a

software reset, then wait 10 ms before initiating I2C commu-

nication with the ADV7281/ADV7281-M/ADV7281-MA.

While the supplies are being established, care must be taken to

ensure that a lower rated supply does not go above a higher rated

supply level. During power-up, all supplies must adhere to the

specifications listed in the Absolute Maximum Ratings section.

POWER-DOWN SEQUENCE

The ADV7281/ADV7281-M/ADV7281-MA supplies can be

deasserted simultaneously as long as DVDDIO does not go below

a lower rated supply.

DVDDIO SUPPLY VOLTAGE

For correct operation of the ADV7281-M/ADV7281-MA, the

DVDDIO supply must be from 2.97 V to 3.63 V.

The ADV7281 can operate with a nominal DVDDIOvoltage of

1.8 V. In this case, apply the power-up sequences described

previously. The only change is that DVDDIO is powered up to

1.8 V instead of 3.3 V.

Note that when the ADV7281 operates with a nominal DVDDIO

voltage of 1.8 V, then drive strength of all digital outputs must

be set to maximum.

Note that when DVDDIO is 1.8 V, the I2C pins of the ADV7281

(SCLK and SDATA) should be pulled up to 1.8V.

3.3V

1.8V

TIME

3.3V SUPPLY

POWER-UP

1.8V SUPPLIES

POWER-UP

3.3V SUPPLY

PWRDWN PIN

POWER-UP

RESET PIN

POWER-UP

RESET PIN

1.8V SUPPLIES

5ms

RESET

OPERATION

5ms

WAIT

Figure 10. Optimal Power-Up Sequence

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