Datasheet

LTC3553
10
3553fb
Buck Regulator Switch
Impedance vs Temperature
TYPICAL PERFORMANCE CHARACTERISTICS
Buck Regulator Feedback
Voltage vs Output Current
Power-Up Sequencing with SEQ
Low
T
A
= 25°C, unless otherwise specifi ed.
TEMPERATURE (°C)
–75 –50 –25 25 50 75 100 1501250
0
SWITCH IMPEDANCE ()
0.4
0.6
1.6
0.8
1.0
1.2
1.4
3553 G28
0.2
PMOS
NMOS
BVIN = 3.2V
STBY = L
OUTPUT CURRENT (mA)
FEEDBACK VOLTAGE (V)
3553 G29
0.1 1 100 100010
0.780
0.790
0.795
0.820
0.800
0.805
0.810
0.815
0.785
3.8V
5V
STBY = L
Regulator Output Transient
During STBY Transition
Buck Regulator Dropout Voltage in
Standby Mode vs Load Current
LOAD CURRENT (mA)
0 5 10 15 20 3025
0
DROPOUT VOLTAGE (mV)
40
60
100
120
140
160
180
200
80
3553 G32
20
–45°C
25°C
90°C
BVIN = 2.9V
BUCK OUTPUT
0.5V/DIV
LDO OUTPUT
1V/DIV
0V
0V
3553 G30
100µs/DIV
FRONT PAGE APPLICATION CIRCUIT
BUCK OUTPUT
0.5V/DIV
LDO OUTPUT
1V/DIV
0V
0V
3553 G33
100µs/DIV
FRONT PAGE APPLICATION CIRCUIT
Power-Up Sequencing with SEQ
High
V
BUS
= 0V
V
BAT
= 3.8V
BUCK OUTPUT
1.2V AT 10mA
20mV/DIV (AC)
LDO OUTPUT
3.3V AT 10mA
50mV/DIV (AC)
HIGH
LOW
STBY
3553 G31
50µs/DIV
TEMPERATURE (°C)
–50 –30 –10 30 50 70 90 13011010
780
FEEDBACK VOLTAGE (mV)
790
795
820
800
805
810
815
3553 G34
785
V
INLDO
= 2.9V
V
INLDO
= 3.8V
V
INLDO
= 5V
100µA LDO LOAD
LDO LOAD (mA)
25 50 75 100 1501250
796
LDO OUTPUT VOLTAGE (mV)
798
799
800
801
3553 G35
797
LDO IN UNITY GAIN
V
INLDO
= 3.8V
V
OUT
= V
BAT
= 3.8V
V
BUS
= 0V
STBY = LOW
V
INLDO
(V)
123 54
0
LDO SHORT-CIRCUIT CURRENT (mA)
100
150
400
200
250
300
350
3553 G36
50
Regulated LDO Feedback Voltage
vs Temperature LDO Load Regulation LDO Short-Circuit Current