LTC3442 Datasheet, PDF (3/20 Pages) Linear Integrated Systems – Micropower Synchronous Buck-Boost DC/DC Converter with Automatic Burst Mode Operation

LTC3442
ELECTRICAL CHARACTERISTICS _{The ● denotes the specifications which apply over the full operating}
temperature range, otherwise specifications are at T_A = 25°C. V_IN = V_OUT = 3.6V, R_T = 64.9k, unless otherwise noted.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Burst Current Ratio
Input Current Ratio
R_LIM Threshold
SHDN/SS Threshold
Ratio of I_OUT to I_BURST
Ratio of I_IN to I_RLIM, I_IN = 0.5A
When IC is Enabled
When EA is at Max Boost Duty Cycle
20,000
70,000
0.95
V
● 0.4
0.7
1.4
V
2.2
2.4
V
SHDN/SS Input Current
V_SHDN = 5.5V
0.01
1
µA
Note 1: Absolute Maximum Ratings are those values beyond which the life
of a device may be impaired.
Note 2: The LTC3442E is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
Note 3: Current Measurements are performed when the outputs are not
switching.
Note 4: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may result in device degradation or failure.
TYPICAL PERFOR A CE CHARACTERISTICS (T_A = 25°C unless otherwise specified).
Efficiency vs Load
100
Burst Mode
90 ^OPERATION _{VIN = 5V}
80 V_IN = 3.3V
V_IN = 3.3V
70
60
V_IN = 2.5V
50
40
V_IN = 2.5V
V_IN = 5V
FIXED FREQUENCY
30
20
0.1
1
V_OUT = 3.3V
600kHz
10 100
LOAD (mA)
1000 10000
3442 G01
Efficiency and Power Loss vs Load
100
Burst Mode
90 ^OPERATION
1000
80
100
70
POWER LOSS
60
10
50
FIXED FREQUENCY
40
1
30
20
0.1
V_IN = 3.6V
V_OUT = 3.3V _0.1
1
10 100 1000 10000
LOAD CURRENT (mA)
3442 G02
Input Current Mirror Linearity
1.00
V_IN = 3.6V
0.90 V_OUT = 3.3V
0.80 ^{RLIM = 133k}
0.70
0.60
0.50
0.40
0.30
0.20
0.10
0.00
0 .05 .10 .15 .20 .25 .30 .35 .40 .45 .50
INPUT CURRENT (A)
3442 G04
Average Input Current Limit
vs V_IN (Normalized)
8
V_OUT = 3.3V
6 ^1MHz
4
2
0
–2
–4
–6
–8
2.5
3.0
3.5
4.0
4.5 5.0
V_IN (V)
3442 G05
Efficiency vs Frequency
96
94
92
WITH SCHOTTKY DIODES
90
88
WITHOUT SCHOTTKY DIODES
86
84
82 _{VIN = 3.6V}
V_OUT = 3.3V
80
400 600 800 1000 1200 1400 1600 1800 2000
FREQUENCY (kHz)
3442 G03
Average Input Current Limit
vs Frequency (Normalized)
15
V_IN = 5V
10
V_OUT SHORTED
5
0
V_OUT DROPS 10%
–5
–10
0.50 0.75 1.00 1.25 1.50 1.75 2.00
FREQUENCY (MHz)
3442 TA01b
3442f
3