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LTC3577_15 Datasheet, PDF (42/54 Pages) Linear Technology – Highly Integrated 6-Channel Portable PMIC
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LTC3577/LTC3577-1
OPERATION
Table 11 shows the final byte of data that can be written
to at sub-address 0x03. This byte of data is referred to as
the “LED PWM register”. See the “LED PWM vs Constant
Current Operation” section for detailed information on
how to set the values of this register.
Table 11. LED PWM Register
LED PWM REGISTER
ADDRESS: 00010010
SUB-ADDRESS: 00000011
BIT NAME
FUNCTION
B0 PWMDEN[0]
PWM DENOMINATOR
B1 PWMDEN[1]
B2 PWMDEN[2]
B3 PWMDEN[3]
B4 PWMNUM[0] PWM NUMERATOR
B5 PWMNUM[1]
B6 PWMNUM[2]
B7 PWMNUM[3]
I2C Output Data
One status byte may be read from the LTC3577. Table 12
represents the status byte information. A 1 read back in
the any of the bit positions indicates that the condition is
true. For example, 1 read back from bit A3 indicate that
LDO1 is enabled and regulating correctly. A status read
from the LTC3577 captures the status information when
the LTC3577 acknowledges its read address.
Table 12. I2C READ Register
STATUS REGISTER
ADDRESS: 00010011
SUB-ADDRESS: None
BIT NAME
FUNCTION
A0 CHARGE
Charge Status (1 = Charging)
A1 STAT[0]
A2 STAT[1]
STAT[1:0]; 00 = No Fault
01 = TOO COLD/HOT
10 = BATTERY OVERTEMP
11 = BATTERY FAULT
A3 PGLDO[1]
LDO1 Power Good
A4 PGLDO[2]
LDO2 Power Good
A5 PGBCK[1]
Buck1 Power Good
A6 PGBCK[2]
Buck2 Power Good
A7 PGBCK[3]
Buck3 Power Good
Bit A7 shows the power good status of buck3. A 1 indicates
that buck3 is enabled and is regulating correctly. A 0 indi-
cates that either buck3 is not enabled, or that the buck3 is
enabled, but is out of regulation by more than 8%.
Bit A6 shows the power good status of buck2. A 1 indicates
that buck2 is enabled and is regulating correctly. A 0 indi-
cates that either buck2 is not enabled, or that the buck2 is
enabled, but is out of regulation by more than 8%.
Bit A5 shows the power good status of buck1. A 1 indicates
that buck1 is enabled and is regulating correctly. A 0 indi-
cates that either buck1 is not enabled, or that the buck1 is
enabled, but is out of regulation by more than 8%.
Bit A4 shows the power good status of LDO2. A 1 indicates
that LDO2 is enabled and is regulating correctly. A 0 indi-
cates that either LDO2 is not enabled, or that the LDO2 is
enabled, but is out of regulation by more than 8%.
Bit A3 shows the power good status of LDO1. A 1 indicates
that LDO1 is enabled and is regulating correctly. A 0 indi-
cates that either LDO1 is not enabled, or that the LDO1 is
enabled, but is out of regulation by more than 8%.
Bits A2 and A1 indicate the fault status of the charger
circuit and are decoded in Table 12. The “too cold/hot”
state indicates that the thermistor temperature is out of
the valid charging range (either below 0°C or above 40°C
for a curve 1 thermistor) and that charging has paused
until a return to valid temperature. The battery overtemp
state indicates that the battery’s thermistor has reached
a critical temperature (above 50°C for a curve 1 thermis-
tor) and that long-term battery capacity may be seriously
compromised if the condition persists. The battery fault
state indicates that an attempt was made to charge a
low battery (typically < 2.85V) but that the low voltage
condition persisted for more than 1/2 hour. In this case
charging has terminated.
Bit A0 indicates the status of the battery charger. A 1 in-
dicates that the charger is enabled and is in the constant
current charge state. In this case the battery is being
charged unless the NTC thermistor is outside its valid
charge range in which case charging is temporarily sus-
pended but not complete. Charging will continue once the
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