LTC3559-1_15 Datasheet, PDF (22/24 Pages) Linear Technology – Linear USB Battery Charger with Dual Buck Regulators

LTC3559/LTC3559-1
TYPICAL APPLICATIONS
The Output Voltage of a Buck Regulator Is Programmed for 3.3V. When BAT Voltage Approaches 3.3V, the Regulator Operates in
Dropout and the Output Voltage Will Be BAT – (I_LOAD • 0.6). An LED at CHRG Gives a Visual Indication of the Battery Charger State.
A 3-Resistor Bias Network for NTC Sets Hot and Cold Trip Points at Approximately 55°C and 0°C
ADAPTER
4.5V TO 5.5V
510Ω
110k
V_CC
1μF
NTC
28.7k
100k
NTC
NTH50603N01
LTC3559/
LTC3559-1
887Ω
CHRG
PROG
SUSP
UP TO
950mA
BAT
PV_IN
+
2.2μF
4.7μH
SW1
1.02M
FB1
324k
SINGLE
Li-lon CELL
2.7V TO 4.2V (LTC3559)
2.7V TO 4.1V (LTC3559-1)
3.3V AT
400mA
22pF
10μF
DIGITALLY
CONTROLLED
HPWR
MODE
SW2
EN1
FB2
EN2
GND EXPOSED PAD
3559 TA03
4.7μH
806k
22pF
649k
1.8V AT
400mA
10μF
Buck Regulator Efficiency vs I_LOAD
100
Burst Mode
90 _OPERATION
80
70
60
50
40
30
20
10
0
0.1
1
PULSE SKIP
MODE
10
I_LOAD (mA)
V_OUT = 1.8V
PV_IN = 2.7V
PV_IN = 4.2V
100
1000
3559 TA02b
Buck Regulator Efficiency vs I_LOAD
100
90
80
70
60
50
40
30
20
10
0
0.1
Burst Mode
OPERATION
PULSE SKIP
MODE
PV_IN = 4.2V
V_OUT = 3.3V
1
10
100
1000
I_LOAD (mA)
3559 TA02c
3559fb
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