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3.2.1.9 DCDC A with LDO C in Parallel

In certain configurations, DCDC A is connected in parallel with LDO C on the printed circuit board, such as 4.1.2 Wired Buck with LDO

C Configuration (EFP0103 & EFP0104) . This configuration is advantageous when the minimum input supply voltage approaches the

VOA output voltage (e.g., VDDBMIN - VOA ≤ 300mV) as it allows EFP01 to continue to regulate the output voltage over a wider input

voltage range than is possible with DCDC A alone.

When LDO C is used in parallel with DCDC A:

• The DCDC mode must be set to WIREDBUCKLDO (i.e., BB_MODE = 3 in the BB_CTRL3 register)

• The input voltage threshold for transition from Buck-to-LDO mode can be adjusted by the NTM_LDO_THRSH bitfield in the

BB_CTRL3 register.

• If inrush current limiting is desired, the BB_IRI_CON bitfield in the BB_CTRL6 register controls the current limit when the converter is

in DCDC mode and the VOC_IRI_CON bitfield in the LDOC_BB_CTRL register controls the current limit when the converter is in

LDO mode.

• When Coulomb counting is enabled, the resulting pulse counts will be split between the CCA_MSBY/LSBY result registers (when

the converter is in DCDC mode) and the CCC_MSBY/LSBY result registers (when the converter is in LDO mode).

Note that when using LDO C in parallel with DCDC A, LDO C is not available as an independent LDO.

3.2.1.10 Low Voltage Charge Pump

The EFP0108 Single-Cell Boost mode enables the use of battery voltages between 0.8V and 1.8V. Because this is below the 1.8V

minimum VDDB operating voltage, the EFP0108 must temporarily generate an internal voltage sufficient to supply VDDB. To do this,

the EFP0108 enables a charge pump supplied from its VDDA pin at startup. Once the internal charge pump output reaches a level

sufficient to supply VDDB, the regular DCDC A Boost powertrain circuitry is enabled and the VOA output is boosted to its target voltage.

At that point, VDDB will be powered from the DCDC A output (VOA is externally connected to VDDB as shown in Figure 4.4 Single-Cell

Boost Configuration on page 33). At this point, the low voltage charge pump is no longer needed and is automatically disabled.

For all other OPNs, the low voltage charge pump is not used, and the VDDA input can safely be grounded.

3.2.2 DCDC B Overview

The EFP01's DCDC B can only be configured for buck mode.

Table 3.3. DCDC B Configuration and Modes Summary

Mode

Required Register Configurations

Buck with LDO B in parallel

BK_CTRL1.BK_MODE = 3

Buck

BK_CTRL1.BK_MODE = 1

3.2.2.1 Output Voltage Configuration

The DCDC B output target voltage in EM0 is set by VOB_EM0_V in the VOB_EM0_V register according to the below equation:

VOB in EM 0 (V ) = 0.8095V + (VOB_EM 0_V × 0.0223V )

In EM2, the DCDC B output target voltage will be automatically set to value specified in the VOB_EM2_V register according to the be-

low equation:

VOB in EM 2 (V ) = 0.8095V + (VOB_EM 2_V × 0.0223V )

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