PCA9420BS datasheet(23/85 Pages) NXP

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NXP Semiconductors

PCA9420

Power management IC for low-power microcontroller applications

When it is under the dead-battery condition, the charging current ICHG_DEAD is programmed by ICHG_DEAD

[5:0]; and when it is under the low-battery condition, the charging current ICHG_LOW is programmed by

ICHG_LOW [5:0]. When VBAT ≥ VBAT_LOW, the charger moves to the next state, fast charging mode.

8.13.5 Constant current charging/constant voltage charging (fast charging) and termination

When VBAT ≥ VBAT_LOW, the charger enters Fast Charge Mode (Constant Current). In this state, the battery

voltage VBAT continues to rise, while the battery is being charged with the current set by ICHG_CC [5:0], until

VBAT reaches the maximum allowable voltage set by VBAT_REG [5:0].

At this time, the charger enters the Constant Voltage (CV) mode. While operating in the CV mode, the voltage is

still regulated at the level set by VBAT_REG [5:0], and the charging current continues to decrease.

When the charging current drops below the top-off current threshold, set by ICHG_TOPOFF [5:0], the charger

enters TOPOFF mode, and upon expiration of TOPOFF timer (set by T_TOPOFF [1:0]), the charger enters

DONE mode.

8.13.6 Charger safety timers

Two sets of charging safety timers are implemented on PCA9420. These timers ensure the charging is

terminated if the charging time is longer than its predefined limit (programmed via I2C registers) at given states:

• Pre-qualification timer, set by ICHG_PREQ_TIMER [1:0], 15 min to 60 min

• Fast charge timer, set by ICHG_FAST_TIMER [1:0], 3 hr to 9 hr

8.13.7 Recharging

While in DONE mode, if the voltage of VBAT stays below (a programmed VBAT_REG – 140 mV or 240 mV)

over the deglitch time (tDGL_BAT_RESTART), 50 ms the battery charger resumes back to Constant Current (CC)

Mode.

8.13.8 Starting a new charge cycle

When a VIN plug in, VBAT attached, or CHG_EN are set to “1”, the device initializes a new charging process.

8.14 Hardware and software reset

Please refer to description for ON pin for the hardware reset function by a long time ON key pressed. The

"software reset” is achieved by setting “1” to SW_RST bit in I2C register. If the user writes a “1” to this bit, it

resets all other I2C register bits to their default setting; this bit is cleared and reset back to “0” as well.

8.15 Device level protection features

The device contains several protection features at both the complete IC level and have a reaction at each of the

functional blocks (linear charger, DC-DC converters, LDOs). There are additional protection mechanisms at the

functional block level, but those are already documented on its respective functional description section.

Protection reaction

Condition

Triggering point

Overall Device state

Linear charger

DC-DC converters

LDOs

VIN undervoltage

VIN < VIN_UVLO

Operational

Disabled

Remain operational

although might deliver a

reduced output voltage

(due to low VIN)

Remain operational

although might deliver a

reduced output voltage

(due to low VIN)

Maintained. Interrupt

triggered, status

reported.

VIN overcurrent

(ILIM)

VIN current is > VIN_

ILIM

Limit input current to

VIN_ILIM setting

Remain operational

Maintained unless reset

happened; Interrupt and

status reported.

Table 6. Device level protection features

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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