P9221-R Datasheet

© 2017 Integrated Device Technology, Inc.

29

October 10, 2017

Table 24. Command Register

Address and Bit

Register Field Name

R/W

Default

Function and Description

004EHEX [7:6]

Reserved

R

0HEX

Reserved.

004EHEX [5]

Clear_Interrupt

RW

0HEX

If application processor sets this bit to "1," the P9221-R clears

the interrupt pin.

004EHEX [4]

Send_Battery_Charge_Status

packet

R

0HEX

If the application processor sets this bit to "1,” the P9221-R

sends the charge status packet once (from the

Batt_Charge_status register; see Table 15) and then sets this

bit to “0.”

004EHEX [3]

Send_End_Power_Transfer

RW

0HEX

If application processor sets this bit to "1," the P9221-R sends

the end power transfer packet (defined in the EPT_Code

register in Table 16) to the transmitter and then sets this bit to

"0."

004EHEX [2]

Reserved

R

0HEX

Reserved

004EHEX [1]

Toggle_LDO_On-OFF

RW

0HEX

If application processor sets this bit to "1,” the P9221-R toggles

the LDO output once (from on to off or from off to on), and then

sets this bit to “0.”

004EHEX [0]

Reserved

R

0HEX

Reserved

12. Application Information

12.1 Power Dissipation and Thermal Requirements

The use of integrated circuits in low-profile and fine-pitch surface-mount packages requires special attention to power dissipation. Many system-

dependent issues such as thermal coupling, airflow, added heat sinks, convection surfaces, and the presence of other heat-generating

components must be taken into consideration.

The P9221-R package has a maximum power dissipation of approximately 1.72W, which is governed by the number of thermal vias between

the package and the printed circuit board. The die’s maximum power dissipation is specified by the junction temperature and the package

thermal resistance. The WLCSP package has a typical θJA of 47ºC/W with 8 thermal vias and 77ºC/W with no thermal vias. Maximizing the

thermal vias is highly recommended.

The ambient temperature surrounding the P9221-R will also have an effect on the thermal limits of the printed circuit board (PCB). The main

factors influencing thermal resistance (θJA) are the PCB characteristics and thermal vias. For example, in a typical still-air environment, a

significant amount of the heat generated is absorbed by the PCB. Changing the design or configuration of the PCB changes the overall thermal

resistivity and therefore the board’s heat-sinking efficiency.

Three basic approaches for enhancing thermal performance are listed below:



Improving the power dissipation capability of the PCB design



Improving the thermal coupling of the component to the PCB.



Introducing airflow into the system.