LTC3553_15 Datasheet, PDF (10/36 Pages) Linear Technology – Micropower USB Power Manager With Li-Ion Charger, LDO and Buck Regulator

LTC3553
Typical Performance Characteristics T_A = 25°C, unless otherwise specified.
Buck Regulator Switch
Impedance vs Temperature
1.6 _{BVIN = 3.2V}
1.4 ^{STBY = L}
PMOS
1.2
1.0
NMOS
0.8
0.6
0.4
0.2
0
–75 –50 –25 0 25 50 75 100 125 150
TEMPERATURE (°C)
3553 G28
Buck Regulator Feedback
Voltage vs Output Current
0.820
0.815
3.8V
5V
STBY = L
0.810
Power-Up Sequencing with SEQ
Low
BUCK OUTPUT
0.5V/DIV
0.805
0V
0.800
0.795
0.790
LDO OUTPUT
1V/DIV
0V
0.785
0.780
0.1
1
10
100
OUTPUT CURRENT (mA)
1000
3553 G29
100µs/DIV
FRONT PAGE APPLICATION CIRCUIT
3553 G30
Regulator Output Transient
During STBY Transition
BUCK OUTPUT
1.2V AT 10mA
20mV/DIV (AC)
LDO OUTPUT
3.3V AT 10mA
50mV/DIV (AC)
HIGH
STBY
LOW
V_BUS = 0V
V_BAT = 3.8V
50µs/DIV
3553 G31
Buck Regulator Dropout Voltage in
Standby Mode vs Load Current
Power-Up Sequencing with SEQ
High
200 _{BVIN = 2.9V}
180
–45°C
25°C
160
90°C
BUCK OUTPUT
0.5V/DIV
140
120
0V
100
LDO OUTPUT
80
1V/DIV
60
40
20
0
0
5 10 15 20 25 30
LOAD CURRENT (mA)
0V
100µs/DIV
FRONT PAGE APPLICATION CIRCUIT
3553 G33
3553 G32
Regulated LDO Feedback Voltage
vs Temperature
820
100µA LDO LOAD
815
V_INLDO = 2.9V
V_INLDO = 3.8V
810
V_INLDO = 5V
805
800
795
790
785
780
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
3553 G34
LDO Load Regulation
801
LDO IN UNITY GAIN
V_INLDO = 3.8V
800
V_OUT = V_BAT = 3.8V
V_BUS = 0V
STBY = LOW
799
798
797
796
0
25 50 75 100 125 150
LDO LOAD (mA)
3553 G35
LDO Short-Circuit Current
400
350
300
250
200
150
100
50
0
1
2
3
4
V_INLDO (V)
5
3553 G36
3553fc
10