Datasheet
LTC3853
3
3853fa
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 3), V
IN
= 15V, V
RUN1,2,3
= 5V, unless otherwise noted.
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
FB1,2,3
Regulated Feedback Voltage I
TH1,2,3
Voltage = 1.2V (Note 4)
I
TH1,2,3
Voltage = 1.2V (0°C to 85°C) (Note 4)
l
0.792
0.794
0.800
0.800
0.808
0.806
V
V
I
FB1,2,3
Feedback Current (Note 4)
–10 –50 nA
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 6V to 24V (Note 4)
0.002 0.02 %/V
V
LOADREG
Output Voltage Load Regulation (Note 4)
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 0.7V
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 1.6V
l
l
0.01
–0.01
0.1
–0.1
%
%
g
m1,2,3
Transconductance Amplifier g
m
I
TH1,2,3
= 1.2V, Sink/Source 5µA (Note 4) 2.2 mmho
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 5)
V
IN
= 15V
V
RUN1,2,3
= 0V
4.1
42
70
mA
µA
UVLO Undervoltage Lockout on INTV
CC
V
INTVCC
Ramping Down 3.35 V
UVLO
HYS
UVLO Hysteresis 0.5 V
V
OVL
Feedback Overvoltage Lockout Measured at V
FB1,2,3
l
0.84 0.86 0.88 V
I
SENSE
Sense Pin Current V
SENSE
= 3.3V ±1 ±2 µA
I
TK/SS1,2,3
Soft-Start Charge Current V
TK/SS1,2,3
= 0V 0.9 1.3 1.7 µA
V
RUN1,2,3
RUN Pin ON Threshold V
RUN1
, V
RUN2
, V
RUN3
Rising
l
1.1 1.2 1.35 V
V
RUN1,2,3HYS
RUN Pin Hysteresis 80 mV
V
SENSE(MAX)
Maximum Current Sense Threshold I
TH1,2,3
= 1.85V, V
SENSE1,2,3
= 3.3V, I
LIM
= 0V
I
TH1,2,3
= 1.85V, V
SENSE1,2,3
= 3.3V, I
LIM
= Float
I
TH1,2,3
= 1.85V, V
SENSE1,2,3
= 3.3V, I
LIM
= INTV
CC
l
l
l
22
42
65
30
50
75
38
58
85
mV
mV
mV
DF
MAX
Maximum Duty Factor In Dropout 97 98 %
TG R
UP
TG Driver Pull-Up On-Resistance TG High 2.6 Ω
TG R
DOWN
TG Driver Pull-Down On-Resistance TG Low 1.5 Ω
BG R
UP
BG Driver Pull-Up On-Resistance BG High 2.4 Ω
BG R
DOWN
BG Driver Pull-Down On-Resistance BG Low 1.1 Ω
TG1,2,3 t
r
TG1,2,3 t
f
TG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
25
25
ns
ns
BG1,2,3 t
r
BG1,2,3 t
f
BG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
25
25
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
(Note 6)
C
LOAD
= 3300pF Each Driver
30
ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
(Note 6)
C
LOAD
= 3300pF Each Driver
30
ns
t
ON(MIN)
Minimum On-Time (Note 7) 90 ns