Datasheet

LTC3577/LTC3577-1
43
3577fa
OPERATION
battery has returned to a valid charging temperature. A 0
in bit A0 indicates that charging has entered the end-of-
charge state (h
C/10
) and is near V
FLOAT
or that charging
has been terminated. Charging can be terminated by
reaching the end of the charge timer or by a battery fault
as described previously.
I
2
C WRITE REGISTER MAP (see the “I
2
C Input Data” section
for more details, all registers default to 0 when reset)
LDO and BUCK CONTOL
REGISTER
ADDRESS: 00010010
SUB-ADDRESS: 00000000
BIT NAME FUNCTION
B0 LDO1EN Enable LDO 1
B1 LDO2EN Enable LDO 2
B2 BK1BRST Buck1 Burst Mode Enable
B3 BK2BRST Buck2 Burst Mode Enable
B4 BK3BRST Buck2 Burst Mode Enable
B5 SLEWCTL1 Buck SW Slew Rate: 00 = 1ns,
01 = 2ns, 10 = 4ns, 11 = 8ns
B6 SLEWCTL2
B7 N/A Not Used—No Effect On Operation
LED CONTROL
REGISTER
ADDRESS: 00010010
SUB-ADDRESS: 00000001
BIT NAME FUNCTION
B0 EN Enable: 1= Enable 0 = Off
B1 GR2
Gradation GR[2:1]: 00 = 15ms, 01 = 460ms,
10 = 930ms, 11 = 1.85 Seconds
B2 GR1
B3 MD1
Mode MD[2:1]: 00 = CC Boost,
10 = PWM Boost, 01 = HV Boost
B4 MD2
B5 PWMC1
PWM CLK PWMC[2:1]: 00 = 8.77kHz,
01 = 4.39kHz, 10 = 2.92kHz, 11 = 2.19kHz
B6 PWMC2
B7 SLEWLED LED SW Slew rate: 0/1 = Fast/Slow
LED DAC REGISTER
ADDRESS: 00010010
SUB-ADDRESS: 00000010
BIT NAME FUNCTION
B0 DAC[0] 6-Bit Log DAC Code
B1 DAC[1]
B2 DAC[2]
B3 DAC[3]
B4 DAC[4]
B5 DAC[5]
B6 N/A Not Used—No Effect On 0peration
B7 N/A Not Used—No Effect On 0peration
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]
PUSHBUTTON INTERFACE OPERATION
State Diagram/Operation
Figure 18 shows the LTC3577 pushbutton state diagram.
Upon fi rst application of power (V
BUS
, WALL or BAT) an
internal power-on reset (POR) signal places the pushbutton
circuitry into the power-down (PDN1) state. One second
after entering the PDN1 state the pushbutton circuitry will
transition into the hard reset (HR) state. The following
events cause the state machine to transition out of HR
into the power-up (PUP1) state:
1) ON input low for 400ms (PB400MS)
2) Application of external power (EXTPWR)
3) PWR_ON input going high (PWR_ON)
PDN2
HRST
PWR_ON
+UVLO
HRST
HRST
1SEC
1SEC
POR
PDN1
PONPOFF
PUP1
HR
5SEC
PB400MS +
EXTPWR +
PWR_ON
PB400MS +
EXTPWR +
PWR_ON
PUP2
5SEC
Figure 18. Pushbutton State Diagram