Datasheet

LTC3785
4
3785fc
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.
elecTrical characTerisTics
Li-Ion to 3.3V Efficiency
vs Load Current
Two Li-Ion to 7V Efficiency
vs Load Current
Li-Ion/9V to 5V V
OUT
Efficiency
vs Load Current
Burst Mode Ripple Line Transient Response V
OUT
Load Transient
T
A
= 25°C, unless otherwise noted.
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
Typical perForMance characTerisTics
LOAD CURRENT (A)
0.0001
EFFICIENCY (%)
60
80
100
1
3785 G01
40
20
50
70
90
30
10
0
0.001
0.01
0.1
10
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 3V
Burst Mode
OPERATION
FIXED
FREQUENCY
MOSFET Si7940
L = 4.7µH WURTH WE-PD
f
OSC
= 500kHz
LOAD CURRENT (A)
0.0001 0.001 0.01 0.1 1
40
EFFICIENCY (%)
50
60
70
80
10
3785 G02
30
20
10
0
90
100
V
IN
= 8.4V
V
IN
= 7.2V
V
IN
= 5.4V
MOSFET Si7940
L = 5.6µH MSS1260
f
OSC
= 430kHz
Burst Mode
OPERATION
FIXED
FREQUENCY
LOAD CURRENT (A)
0.0001 0.001 0.01 0.1 1
40
EFFICIENCY (%)
50
60
70
80
10
3785 G03
30
20
10
0
90
100
V
IN
= 9V
V
IN
= 4.2V
V
IN
= 3.6V
V
IN
= 2.7V
MOSFET Si7940
L = 5.6µH MSS1260
f
OSC
= 430kHz
Burst Mode
OPERATION
FIXED
FREQUENCY
V
OUT
50mV/DIV
AC
COUPLED
INDUCTOR
CURRENT
1A/DIV
5µs/DIVV
OUT
= 3.3V
C
OUT
= 100µF
3785 G04
V
OUT
500mV/
DIV
V
IN
3V TO
8.5V
500µs/DIVI
LOAD
= 300mA
V
OUT
= 5V
C
OUT
= 100µF
3785 G05
V
OUT
200mV/
DIV
I
LOAD
10mA TO 2A
100µs/DIVV
IN
= 3.6V
V
OUT
= 3.3V
C
OUT
= 100µF
3785 G06
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.
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