LTC3785_15 Datasheet, PDF (4/20 Pages) Linear Technology – 10V, High Efficiency, Synchronous, No RSENSE Buck-Boost Controller

LTC3785
electrical Characteristics The l denotes the specifications which apply over the full operating junction
temperature range, otherwise specifications are at T_A = 25°C. V_IN = I_SVOUT = V_DRV = V_BST1 = V_BST2 = 3.6V, R_T = 49.9k, R_ILSET = 59k.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
BG1, BG2 Rise Time
C_LOAD = 3300pF (Note 3)
20
ns
TG1, TG2 Fall Time
C_LOAD = 3300pF (Note 3)
20
ns
BG1, BG2 Fall Time
C_LOAD = 3300pF (Note 3)
20
ns
Buck Driver Nonoverlap Time
TG1 to BG1
100
ns
Boost Driver Nonoverlap Time
TG2 to BG2
100
ns
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3785E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3785I is guaranteed
to meet performance specifications over the full –40°C to 125°C operating
junction temperature range.
Note 3: Specification is guaranteed by design and not 100% tested in
production.
Note 4: Current measurements are performed when the outputs are not
switching.
Note 5: The IC is tested in a feedback loop to make the measurement.
Typical Performance Characteristics T_A = 25°C, unless otherwise noted.
Li-Ion to 3.3V Efficiency
vs Load Current
100
Burst Mode
90 _OPERATION
80
70
60
FIXED
FREQUENCY
50
40
30
20
10
0
0.0001
V_IN = 4.2V
V_IN = 3.6V
V_IN = 3V
MOSFET Si7940
L = 4.7µH WURTH WE-PD
f_OSC = 500kHz
0.001 0.01 0.1
1
10
LOAD CURRENT (A)
3785 G01
Two Li-Ion to 7V Efficiency
vs Load Current
100
90 Burst Mode
OPERATION
80
70
60
FIXED
FREQUENCY
50
40
30
20
10
0
0.0001
V_IN = 8.4V
V_IN = 7.2V
V_IN = 5.4V
MOSFET Si7940
L = 5.6µH MSS1260
f_OSC = 430kHz
0.001 0.01 0.1
1
10
LOAD CURRENT (A)
3785 G02
Li-Ion/9V to 5V V_OUT Efficiency
vs Load Current
100
Burst Mode
90 _OPERATION
80
70
60
50
40
30
20
10
0
0.0001
FIXED
FREQUENCY
V_IN = 9V
V_IN = 4.2V
V_IN = 3.6V
V_IN = 2.7V
MOSFET Si7940
L = 5.6µH MSS1260
f_OSC = 430kHz
0.001 0.01 0.1
1
10
LOAD CURRENT (A)
3785 G03
Burst Mode Ripple
V_OUT
50mV/DIV
AC
COUPLED
INDUCTOR
CURRENT
1A/DIV
V_OUT = 3.3V
C_OUT = 100µF
5µs/DIV
Line Transient Response
V_OUT
500mV/
DIV
3785 G04
V_IN
3V TO
8.5V
I_LOAD = 300mA 500µs/DIV
V_OUT = 5V
C_OUT = 100µF
V_OUT Load Transient
V_OUT
200mV/
DIV
I_LOAD
10mA TO 2A
3785 G05
V_IN = 3.6V
V_OUT = 3.3V
C_OUT = 100µF
100µs/DIV
3785 G06
3785fc