Data Sheet

ManualsBrandsON SEMICONDUCTOR ManualsPMICsPMIC - battery management Charge management Li-Ion, Li-Po WLCSP 20 Surface-mount

FAN5400 Family • Rev. 1.10 25

FAN5400 Family — USB-Compliant Single-Cell Li-Ion Switching Charger with USB-OTG Boost Regulator

Additional 

data points, measured using the FAN540X

evaluation board, are given in Table 11 (measured with

=25°C). Note that as power dissipation increases, the

effective 

decreases due to the larger difference between

the die temperature and its ambient.

Table 11. FAN5400 Evaluation Board Measured 

Power (W)





0.504

54°C / W

0.844

50°C / W

1.506

46°C / W

Charge Mode Input Supply Protection

Sleep Mode

When V

BUS

falls below V

BAT

+ V

SLP

, and V

BUS

is above

IN(MIN),

the IC enters Sleep Mode to prevent the battery from

draining into VBUS. During Sleep Mode, reverse current is

disabled by body switching Q1.

Input Supply Low-Voltage Detection

The IC continuously monitors VBUS during charging. If V

BUS

falls below V

IN(MIN)

, the IC:

1. Terminates charging

2. Pulses the STAT pin, sets the STAT bits to 11, and sets

the FAULT bits to 011.

If V

BUS

recovers above the V

IN(MIN)

rising threshold after time

INT

(about two seconds), the charging process is repeated.

This function prevents the USB power bus from collapsing or

oscillating when the IC is connected to a suspended USB

port or a low-current-capable OTG device.

Input Over-Voltage Detection

When the V

BUS

exceeds VBUS

OVP

, the IC:

1. Turns off Q3

2. Suspends charging

3. Sets the FAULT bits to 001, sets the STAT bits to 11,

and pulses the STAT pin.

When V

BUS

falls about 150 mV below VBUS

OVP

, the fault is

cleared and charging resumes after V

BUS

is revalidated (see

VBUS POR / Non-Compliant Charger Rejection).

VBUS Short While Charging

If VBUS is shorted with a very low impedance while the IC is

charging with I

INLIMIT

=100 mA, the IC may not meet

datasheet specifications until power is removed. To trigger

this condition, V

BUS

must be driven from 5 V to GND with a

high slew rate. Achieving this slew rate requires a 0  short

to the USB cable less than 10cm from the connector.

Charge Mode Battery Detection & Protection

VBAT Over-Voltage Protection

The OREG voltage regulation loop prevents V

BAT

from

overshooting the OREG voltage by more than 50 mV when

the battery is removed. When the PWM charger runs with no

battery, the TE bit is not set and a battery is inserted that is

charged to a voltage higher than V

OREG

; PWM pulses stop. If

no further pulses occur for 30 ms, the IC sets the FAULT bits

to 100, sets the STAT bits to 11, and pulses the STAT pin.

Battery Detection During Charging

The IC can detect the presence, absence, or removal of a

battery if the termination bit (TE) is set. During normal

charging, once V

BAT

is close to V

OREG

and the termination

charge current is detected, the IC terminates charging and

sets the STAT bits to 10. It then turns on a discharge current,

DETECT

, for t

DETECT

. If V

BAT

is still above V

OREG

– V

RCH

, the

battery is present and the IC sets the FAULT bits to 000. If

BAT

is below V

OREG

– V

RCH

, the battery is absent and the IC:

1. Sets the registers to their default values.

2. Sets the FAULT bits to 111.

3. Resumes charging with default values after t

INT

Battery Short-Circuit Protection

If the battery voltage is below the short-circuit threshold

SHORT

); a linear current source, I

SHORT

, supplies V

BAT

until

BAT

> V

SHORT

Battery Detection During Power-up

For FAN5400 and FAN5403

At VBUS POR, a 5 k load is applied to VBAT for 500 ms to

discharge any residual system capacitance in case the

battery is absent. If V

BAT

< V

SHORT

, linear charging

commences. When V

BAT

rises above V

SHORT

, PWM charging

proceeds with the float voltage (OREG) temporarily set to

4 V. If the battery voltage exceeds 3.7 V within 32 ms of the

beginning of PWM charging, the battery is absent. If battery

absent is detected:

1. High-Impedance Mode is entered.

2. FAULT bits are set to 111.

3. The t

15MIN

timer is disabled until VBUS is removed.

If V

BAT

remains below 3.7 V during the initial 32 ms period,

the float voltage returns to the OREG register setting and

PWM charging continues.

System Operation with No Battery

The FAN5402 and FAN5405 continue charging after VBUS

POR with the default parameters, regulating the V

BAT

line to

3.54 V until the host processor issues commands or the 15-

minute timer expires. In this way, the FAN5402 and

FAN5405 can start the system without a battery.

The FAN540X soft-start function can interfere with the

system supply with battery absent. The soft-start activates

whenever V

OREG

, I

INLIM

, or I

OCHARGE

are set from a lower to

higher value. During soft-start, the I

limit drops to 100 mA

for about 1 ms unless I

INLIM

is set to 11 (no limit). This could

cause the system processor to fail to start. To avoid this

behavior, use the following sequence.

1. Set the OTG pin HIGH. When VBUS is plugged in, I

INLIM

is set to 500 mA until the system processor powers up

and can set parameters through I

2. Program the Safety Register.

3. Set I

INLIM

to 11 (no limit).

4. Set OREG to the desired value (typically 4.18).

5. Reset the IOLEVEL bit, then set IOCHARGE.

6. Set I

INLIM

to 500mA if a USB source is connected.