R16AN0002EU0300 Rev.3.00
Page 12
Jan 6, 2022
ISL9241 Operation Modes Application Note
2.4
Adapter Removal Events
When the ISL9241 operates in NVDC mode, it can automatically detect adapter removal and operate in Battery
Only mode independently. When the ISL9241 is in Bypass mode (with or without charging and Reverse Turbo
Boost), it can still detect the adapter removal event, but may need additional commands from the host controller to
turn off Bypass FETs and turn on the NGATE FETs so it can deliver full power from the battery with minimal
voltage drop and loss. These commands from the host also ensure that the Bypass FETs are not automatically
turned on when the adapter is plugged in the next time (for example, a low voltage adapter that cannot support
Bypass mode).
Table 4. Adapter Removal Events
[1]
From State
To State
Step
Number
Function Description
Register Name
Value
(Decimal)
Register
Address
Bypass
BAT
Monitor ACOK – when ACOK
goes low, complete the following
steps before connecting another
adapter
1
Disable Force Forward
Buck/Reverse Boost bit
Control 4
0
0x4E
2
Turn off BYPSG, Turn on
NGATE, Disable Charge pump
100% and disable V
IN
<V
OUT
comparator
Control 0
0
0x39
3
Set MaxSysVoltage register to
full charge voltage
MaxSysVoltage
Battery or
system specific
0x15
4
Disable ADC
Control 3
300
0x4C
5
BGATE to Normal operation
Control 1 <6>
0
0x3C
6
Reset ACOKref register to
normal value to detect low
voltage (5V or 9V) adapter during
next plug in event
ACOKREF
3.6V or desired
level
0x40
CHRG
BAT
Monitor ACOK – when ACOK
goes low, complete the following
steps before connecting another
adapter
ACOK must be set above
MaxSysVoltage for this mode
1
Disable Force Forward
Buck/Reverse Boost bit
Control 4
0
0x4E
2
Set Charge Current to 0 to
disable fast charging
ChargeCurrentLimit
0
0x14
3
Set MinSysVoltage to 0 to
disable trickle charging
MinSysVoltage
0
0x3E
4
Turn off BYPSG, turn on NGATE,
disable charge pump 100% and
disable V
IN
<V
OUT
comparator
Control 0
0
0x39
5
Disable ADC
Control 3
300
0x4C
6
BGATE to Normal operation
Control 1 <6>
0
0x3C
7
Reset ACOKref register to
normal value to detect low
voltage (5V or 9V) adapter during
next plug in event
ACOKREF
3.6V or desired
level
0x40
