LTC2972 datasheet(109/112 Pages) LINER

109 / 112 page

LTC2972

109

2972fa

For more information www.linear.com/LTC2972

APPLICATIONS INFORMATION

DESIGN CHECKLIST

I2C

The LTC2972 must be configured for a unique address.

Theaddressselectpins(ASEL

n)aretri-level;CheckTable1.

Check addresses for collision with other devices on the

bus and any global addresses.

Output Enables

Use appropriate pull-up resistors on both VOUT_ENn pins.

Verify that the absolute maximum ratings of the VOUT_ENn

pins are not exceeded.

VIN Sense

No external resistive divider is required to sense VIN;

VIN_SNS already has an internal calibrated divider.

Input Current Sense

Verify that IIN_SNSP and IIN_SNSM pins do not exceed ab-

solute maximum ratings.

Add a 10nF capacitor to VIN_SNS_CAP.

External Temperature Sense

Verify the PNP sense transistor is close to the inductor

and away from other significant heat sources.

Verify the PNP sense transistor collector connects to

a ground plane near the PNP, the emitter routes to the

LTC2972, and the base connects to signal ground near

the LTC2972.

Logic Signals

Verify the absolute maximum ratings of the digital pins

(SCL, SDA, ALERTB, FAULTB

n, CONTROLn, SHARE_CLK,

WDI, ASEL

n, PWRGD) are not exceeded.

Connect all SHARE_CLK pins in the system together and

pull-up to VDD33 with a 5.49k resistor.

Do not leave CONTROLn pins floating. Pull up to VDDIO

with a 10k resistor.

Tie WDI/RESETB to VDD33 with a 10k resistor. Do not

connect a capacitor to the WDI/RESETB pin.

Tie WP to either VDDIO or GND. Do not leave floating.

Do not leave the FAULTBn pins floating. Pull up to VDDIO

with a 10k resistor.

Unused Inputs

ConnectallunusedVSENSEPn,VSENSEMn,ISENSEPn,ISENSEMn,

and TSENSEn pins to GND. Do not float unused inputs.

Refer to Unused ADC Sense Inputs in the Applications

Information section.

If not used, connect IIN_SNSP and IIN_SNSM pins to the

VIN_SNS pin.

DAC Outputs

Selectappropriateresistorfordesiredmarginrange.Refer

totheresistorselectiontoolinLTpowerPlayforassistance.

For a more complete list of design considerations and

a schematic checklist, see the Design Checklist on the

LTC2972 product page:

LTC2972 Datasheet(PDF) 109 Page - Linear Technology

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