Datasheet

LTC4156
29
4156f
Table 3. Interrupt Mask Register
INTERRUPT MASK REGISTER (IMR)
SUB ADDRESS 0x06 REG6
DIRECTION Write/Clear Interrupt, Read
D7 D6 D5 D4 D3 D2 D1 D0
ENABLE_CHARGER_INT 1
ENABLE_FAULT_INT 1
ENABLE_EXTPWR_INT 1
ENABLE_OTG_INT 1
ENABLE_AT_ILIM_INT 1
ENABLE_INPUT_UVCL_INT 1
Table 4. Interrupt Trigger Sources
MASK CATEGORY STATUS TRIGGERS
STATUS
REGISTERS
ENABLE_CHARGER_INT CHARGER_STATUS[2:0] 0x03
ENABLE_FAULT_INT OVP_ACTIVE
BAD_CELL
OTG_FAULT
NTC_HOT_FAULT
0x03
0x04
ENABLE_EXTPWR_INT USBSNS_GOOD
WALLSNS_GOOD
EXT_PWR_GOOD
0x04
ENABLE_OTG_INT OTG_ENABLED
ID_PIN_DETECT
0x03
ENABLE_AT_ILIM_INT AT_INPUT_ILIM 0x04
ENABLE_INPUT_UVCL_INT INPUT_UVCL_ACTIVE 0x04
Alternate Default Input Current Limit
For USB compatible operation, connect both the CLPROG1
and CLPROG2 pins to a single 1.21k 1% resistor, as
shown in Figure 5. When input power is applied, the
LTC4156 will default to the 100mA input current limit
mode. The I
2
C bus master may then subsequently change
the input current limit to any of the other modes listed in
Table 8, where the 500mA and 900mA settings also cor-
respond to USB compatible current limits. If input power is
removed and reapplied, the LTC4156 will once again default
to 100mA mode until commanded to do otherwise by I
2
C.
If the 100mA USB default current limit is insufficient for
the application and USB compliance is not necessary, an
alternate non-USB compliant default input current may
be programmed with a second resistor on the CLPROG1
pin
, as shown in Figure 6.
The resistor should be sized using the following equation:
R
CLPROG1
=
1.200V
I
VBUSLIM
– I
VBUSQ
( )
• 991
( )
When input power is applied, the LTC4156 will default
to the current limit set by the resistor connected to the
CLPROG1 pin. The I
2
C bus master may then subsequently
change the input current limit to any of the other modes
listed in Table 8, which require a second 1.21k program-
ming resistor on the CLPROG2 pin. The I
2
C master may
also change back to the default
input current limit at any
time by setting the appropriate USBILIM or WALLILIM
bits to the CLPROG1 mode. If input power is removed
and reapplied at any time, the LTC4156 will again default
to the CLPROG1 custom input current limit.
The contents of USBILIM[4:0] and WALLILIM[4:0] always
contain the currently selected input current modes, which
may be different from the data last written by the I
2
C bus
master if input power was subsequently removed or was
not present. The I
2
C bus master can read the above two
registers at any time to determine the active input current
limit mode.
CLPROG2CLPROG1
LTC4156
4156 F05
Figure 5. USB Default Input Current Limit
OPERATION
CLPROG2CLPROG1
R2R1
LTC4156
4156 F06
Figure 6. Non-USB Default Input Current Limit