Datasheet

LTC3559/LTC3559-1
22
3559fb
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
V
CC
NTC
CHRG
PROG
SUSP
HPWR
EN1
4.7μH
2.2μF
10μF
324k
1.02M
649k
806k
10μF
22pF
22pF
UP TO
950mA
LTC3559/
LTC3559-1
GND EXPOSED PAD
1μF
110k510Ω
100k
NTC
NTH50603N01
4.7μH
887Ω
EN2
MODE
BAT
ADAPTER
4.5V TO 5.5V
PV
IN
SW1
FB1
SW2
DIGITALLY
CONTROLLED
FB2
SINGLE
Li-lon CELL
2.7V TO 4.2V (LTC3559)
2.7V TO 4.1V (LTC3559-1)
1.8V AT
400mA
3.3V AT
400mA
28.7k
3559 TA03
+
TYPICAL APPLICATIONS
Buck Regulator Effi ciency vs I
LOAD
Buck Regulator Effi ciency vs I
LOAD
I
LOAD
(mA)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.1 10 100 1000
3559 TA02b
0
1
PV
IN
= 2.7V
PV
IN
= 4.2V
V
OUT
= 1.8V
Burst Mode
OPERATION
PULSE SKIP
MODE
I
LOAD
(mA)
30
EFFICIENCY (%)
90
100
20
10
80
50
70
60
40
0.1 10 100 1000
3559 TA02c
0
1
PV
IN
= 4.2V
V
OUT
= 3.3V
Burst Mode
OPERATION
PULSE SKIP
MODE