PCA9420 datasheet(18/87 Pages) NXP

18 / 87 page

NXP Semiconductors

PCA9420

Power management IC for low-power microcontroller applications

Hardware Reset (ON Long Press) shuts down LDO1 and recycles power up to default

output voltage.

8.11.7 LDO2 (system LDO)

The LDO2 (system LDO) output can be programmed via the I2C register from 1.5 V to

2.1 V, or 2.7 V to 3.3 V at 25 mV/step. Typically, a 2.2 µF/6.3 V MLCC output capacitor

providing at least 250 mA loading current is needed.

8.12 Linear battery charger

The battery charger is a linear charger. Its charging is done through a linear switch with

the following output protections:

• Reverse current protection

– (triggers when ASYS < VBAT+ VINBAT_HEADROOM*)

• Charging current limiting

– (a function of programmed threshold and battery temperature)

• VBAT short circuit protection

– Short circuit output voltage threshold: (typ 0.8 V with 80 mV hysteresis)

– Maximum output sourcing current during “short circuit” detection ~ 13 mA

(VIN2BAT_HEADROOM = 100 mV, typical)

If the battery voltage is below the VBAT_LOW threshold, the battery is considered

discharged and a preconditioning cycle begins. The amount of pre-charge current

(ICHG_LOW) can be programmed through I2C register setting. This feature is useful

when there is a load connected directly across the battery (at VBAT pin) “stealing” the

battery current. The pre-charge current can be set higher to account for the system

loading while allowing the battery to be properly conditioned. Once the battery voltage

has charged to the VBAT_LOW threshold, fast charge is initiated and a programmed fast

charge current (ICHG_CC) is applied. The fast charge constant current is programmed

using I2C register. The constant current provides the bulk of the charge. Power

dissipation in the device is greatest in fast charge with a lower battery voltage.

If the device reaches a programmed thermal regulation threshold temperature (defined

by the configuration on the THM_REG bit fields on the CHG_CNTL7 register) from 85 °C

to 115 °C in 5 °C steps, the device enters thermal regulation. This is indicated by the

TREG_STATUS bit field on the CHG_STATUS_1 register. Thermal regulation increases

the safe-charging-timer period by 2x and reduces the charge current in half (if the initial

current is 5 mA, it will remain unchanged) to keep the temperature from rising any further

when battery charger works in constant current charging mode, or at a reduced regulated

voltage when battery charger works in constant voltage charging mode.

Figure 9 shows the charging profile with a dead battery condition. Once the cell has

charged to the regulation voltage (VBAT_REG) the voltage loop takes control and holds

the battery at the regulation voltage until the current tapers to the termination threshold

(ICHG_TOPOFF).

CHG_LOCK [4:0] bits on Battery charger control_0 (CHG_CTL0, address 10h) register

should be set to ‘10101’ to be able to perform I2C “write” command. Otherwise, when

“write” command is performed on the ‘locked registers’, it keeps the present register

value.

PCA9420

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

Product data sheet

Rev. 4.0 — 28 November 2022

18 / 87

PCA9420 Datasheet(PDF) 18 Page - NXP Semiconductors

PCA9420 Datasheet(HTML) 18 Page - NXP Semiconductors

Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 66 67 68 69 70 71 72 73 74 75 76 77 78 79 80 81 82 83 84 85 86 87

Datasheet Download

Link URL