EFP01 datasheet(10/158 Pages) SILABS

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3.2.1.2 Peak Current Configuration

DCDC A has a configurable peak current adjustment set by the BB_IPK and BB_IPK_EM2 fields of the BB_IPK register. The BB_IPK

and BB_IPK_EM2 settings are used differently depending on the operating mode of the DCDC A converter (as shown below), but the

resulting peak currents for all modes are derived from the following base peak current (IPK_BASE) equations.

In EM0, IPK_BASE is determined by: IPK _ BASE = 0.090A + (0.009A × BB _ IPK )

In EM2, IPK_BASE is determined by: IPK _ BASE = 0.090A + 0.009A × (4 × BB _ IPK _ EM 2 + 2)

Typically, the peak current can be lowered in EM2 for greater efficiency. However, unlike DCDC B there is only a single Coulomb coun-

ter for DCDC A that is used in both EM0 and EM2 modes. Therefore, if Coulomb counting is used with DCDC A, BB_IPK_EM2 must be

set such that the peak current in EM2 is the same as the peak current in EM0 to ensure the charge per pulse is the same in both

energy modes. Roughly equivalent peak currents in EM2 and EM0 can be achieved by setting BB_IPK_EM2 = ( BB_IPK - 2 ) / 4.

Note: The Maximum Output Current formulas below provide useful guidance but are not a guarantee of performance. The final authori-

ty for the Maximum Output Current will be the Output Load Current specifications in the Electrical Characteristics tables.

Buck Mode

• Register Programming: BB_CTRL3.BB_MODE = WiredBuck or Autonomous

•

Peak Current

(A) = IPK_BASE + 25ns ×(VDDB-VOA)

L A

• Maximum Output Current (A) = 0.5 × IPK _ BASE

Buck/Boost Mode (NTM Operation)

• Register Programming: BB_CTRL3.BB_MODE = Autonomous

•

Peak Current

(A) = 1.15 × IPK_BASE + 25ns ×VDDB

L A

• Maximum Output Current (A) = 0.5 × 1.15 × IPK _ BASE

Boost Mode (with no peak current adjustment)

• Register Programming: BB_CTRL3.BB_MODE = WiredBoost or Autonomous, BB_CTRL6.BB_IPK_NOADJ = 1

•

Peak Current

(A) = 2.35 × IPK_BASE + 25ns ×VBOOST

L A

•

Maximum Output Current

(A) = efficiency × 0.5 × 2.35 × IPK _BASE × VBOOST

VOA

Boost Mode (with peak current adjustment)

• Register

Programming:

BB_CTRL3.BB_MODE

WiredBoost

Autonomous,BB_CTRL6.BB_IPK_NOADJ

BB_CTRL5.BB_IPK_BOOST_ADJ is programmed as recommended in its register description, ADC_CC_CTRL.ADC_INTERVAL >

0 to enable ADC operations.

• When operating in Boost Mode with peak current adjustment, the peak current will be adjusted to maintain a near constant output

load current over the battery voltage range. Note that peak current adjustment only affects EM0 operation. In EM2, the Boost Mode

(with no peak current adjustment) equations apply.

•

Peak Current

(A) = 2.35 ×MIN(IPK_BASE ×VOA

2 × VBOOST

385mA

)+ 25ns ×VBOOST

L A

•

Maximum Output Current

(A) = efficiency × 0.5 × 2.35 × MIN(IPK _BASE × VOA

2 × VBOOST

385mA

) × VBOOST

VOA

EFP01 Energy Friendly PMIC Family Data Sheet

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