PCA9420BS datasheet(10/85 Pages) NXP

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NXP Semiconductors

PCA9420

Power management IC for low-power microcontroller applications

8.2 VIN

The VIN pin serves as the input power for ASYS and VBAT and has the following functions implemented:

• An I2C undervoltage lockout protection threshold (VIN_UVLO_SEL)

• An I2C programmable input current limiting threshold (falling, VIN_ILIM_SEL [2:0] ) which can be disabled.

When the VIN_ILIM threshold is reached, the VIN current clamps at that VIN_ILIM_SEL level. This current

limiting only applies to VIN

• 20 V tolerance on VIN pin

• An I2C programmable overvoltage protection threshold (rising, VIN_OVP_SEL)

8.2.1 VIN_ILIM and VSYS/VBAT interaction cases

The following describe potential use cases where the behavior of VSYS & the Battery Charger change

according to the VIN_ILIM event.

8.2.1.1 Case 0: Battery charger in attach detection sequence & VIN current < VIN_ILIM

The sum of VSYS current (ISYS) and VBAT current (IBAT) in the attach detection sequence is lower than

VIN_ILIM current threshold; current clamping does not occur and VSYS voltage follows VIN.

8.2.1.2 Case 1: Battery charger active & VIN current < VIN_LIM

The sum of ISYS and IBAT (battery charging profile ongoing) is lower than VIN_ILIM current threshold; current

clamping does not occur and VSYS voltage follows VIN.

8.2.1.3 Case 2: Battery charger active & VIN current increases above VIN_LIM (ISYS <

VIN_ILIM)

The sum of an increasing ISYS and IBAT is greater than VIN_ILIM, causing the following events:

• VIN current is clamped to VIN_ILIM while battery charging current continues

• This produces a ramp down in VSYS

• When VSYS is equal to VBAT, charger resets and stops charging.

• The current demand from VSYS is now lower than VIN_ILIM and VSYS is restores to VIN, causing VSYS to

rise again. When VSYS > VBAT+100mV, charger automatically restarts from its initial state but may not reach

the next charging sequence (pre-charge or fast charge) depending on if the VIN_ILIM threshold is reached.

This cycle repeats every 300 ms as described in the battery attached detection sequence.

8.2.1.4 Case 3: Battery charger active & VIN current decreasing below VIN_LIM (ISYS <

VIN_ILIM)

With starting conditions from Case 2 now the sum of a decreasing ISYS and IBAT is lower than VIN_ILIM and

since VSYS > VBAT+100mV charger automatically restarts from its initial state and goes to the next charging

sequence as long as VIN_ILIM is not reached.

8.2.1.5 Case 4: VIN current increasing above VIN_LIM and Battery supplemental mode

activation (ISYS > VIN_ILIM)

ISYS current increases until VIN_ILIM is triggered. VIN current is then clamped to VIN_ILIM, producing a

ramp down in VSYS. When VSYS < VBAT is reached, a current path from VBAT to VSYS is enabled (Battery

supplemental mode activation) to provide the needed current as VIN is limited. PMIC continues to operate this

way until ISYS demand drops below VIN_ILIM, and goes back to one of the previous cases.

PCA9420

All information provided in this document is subject to legal disclaimers.

Product data sheet

Rev. 4.2 — 26 July 2023

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