LTC4099 Linear Technology Corporation, LTC4099 Datasheet - Page 23

• Manufacturer Part Number: LTC4099
• Description: I2C Controlled USB Power Manager/Charger
• Manufacturer: Linear Technology Corporation

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OPERATION
The battery charger current settings are decoded in
Table 3. The battery charger current settings are adjusted
by selecting one of the eight servo voltages for the PROG
pin. Recall that the programmed charge current is given
by the expression:
The default state for the battery charger current settings is
000, giving the lowest available servo voltage of 500mV.
The COVERX1 and COVERX0 bits are decoded in Table 4.
The C/x setting controls the PROG pin level that the
LTC4099’s C/x comparator uses to report full capacity
charge. For example, if the 100mV setting is chosen, then
the LTC4099 reports that its PROG pin voltage has fallen
below 100mV. For the 50mV setting, LTC4099 reports
that its PROG pin voltage has fallen below 50mV. The C/x
settings are adjusted by comparing the PROG pin voltage
Table 1. LTC4099 Input Data Bytes
Bit 7
Bit 6
Bit 5
Bit 4
Bit 3
Bit 2
Bit 1
Bit 0
Table 2. I
*Default Setting
I
I
CHG
LIM2
0
0
0
0
1
1
1
1
SUB ADDRESS 0
LIM2
REGISTER 0
R
COMMAND
V
COVERX1
COVERX0
I
I
I
CHARGE2
CHARGE1
CHARGE0
PROG
PROG
– I
I
I
I
LIM2
LIM1
LIM0
USB INPUT CURRENT LIMIT SETTINGS
I
LIM1
LIM0
0
0
1
1
0
0
1
1
• 1030
Decode
DISABLE_CHARGER
ENABLE_ BATTERY_
I
LIM0
SUB ADDRESS 1
0
1
0
1
0
1
0
1
CONDITIONER
V
REGISTER 1
T
COMMAND
FLOAT
REG
Not Used
TIMER2
TIMER1
TIMER0
= 85°C
= 4.2V
Suspend High (2.5mA)
Suspend Low (500μA)
100mA*
1000mA
1200mA
500mA
620mA
790mA
CHARGER_STATUS
SUB ADDRESS 2
I
THERMAL_ REG
THERMISTOR_
USB
WALLGOOD
IRQ MASK
REGISTER
USBGOOD
BADCELL
Not Used
Not Used
STATUS
with the values shows in Table 4. The default value for the
C/x setting is 00, giving 100mV detection.
The second byte of data at sub address 0x01 controls the
three battery charger safety timer bits, TIMER2-TIMER0,
the DISABLE_CHARGER bit, the ENABLE_BATTERY_
CONDITIONER bit, the V
T
The TIMER2–TIMER0 bits control the duration of the bat-
tery charger safety timer. The safety timer starts once the
LTC4099 reaches the 4.100V or the 4.200V fl oat voltage.
As long as input power is available, charging will con-
tinue in fl oat voltage mode until the safety timer expires.
Table 5 lists the possible safety timer settings from 1 to
8 hours, and how to decode them. The default state for
the LTC4099 safety timer is 4 hours.
The DISABLE_CHARGER bit can be used to prevent battery
charging if needed. This bit should be used with caution
Table 3. I
*Default Setting
Table 4. C/x Decode
*Default Setting
REG
COVERX1
I
CHARGE2
0
0
0
0
1
1
1
1
0
0
1
1
= 85°C control bit.
CHARGE2
BATTERY CHARGER CURRENT LIMIT SETTINGS
COVERX0
I
CHARGE1
0
0
1
1
0
0
1
1
0
1
0
1
– I
CHARGE0
C/x INDICATION SETTINGS
I
100mV*
CHARGE0
200mV
500mV
V
50mV
PROG
0
1
0
1
0
1
0
1
Decode
FLOAT
= 4.2V control bit and the
500mV*
1000mV
1100mV
1200mV
600mV
700mV
800mV
900mV
V
PROG
FULL CAPACITY CHARGE
R
INDICATION
PROG
LTC4099
100mA*
200mA
500mA
CHARGE CURRENT
50mA
R
= 1.02k
PROG
1000mA
1100mA
1200mA
500mA
600mA
700mA
800mA
900mA
= 1.02k
23
4099f