Datasheet

LTC3850/LTC3850-1
4
38501fc
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
FB1,2
Regulated Feedback Voltage I
TH1,2
Voltage = 1.2V; (Note 4)
l
0.792 0.800 0.808 V
I
FB1,2
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
Transconductance Amplifier g
m
I
TH1,2
= 1.2V; Sink/Source 5µA; (Note 4) 2.2 mmho
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 5)
V
IN
= 15V; EXTV
CC
Tied to V
OUT1
; V
OUT1
= 5V
V
RUN1,2
= 0V
850
30 50
µA
µA
UVLO Undervoltage Lockout on INTV
CC
V
INTVCC
Ramping Down 3 V
UVLO
HYS
UVLO Hysteresis 0.5 V
DF
MAX
Maximum Duty Factor In Dropout 96 97.2 %
V
OVL
Feedback Overvoltage Lockout Measured at V
FB1,2
l
0.84 0.86 0.88 V
I
SENSE
Sense Pin Bias Current (Each Channel) V
SENSE1,2
= 3.3V ±1 ±2 µA
I
TK/SS1,2
Soft-Start Charge Current V
TK/SS1,2
= 0V 0.9 1.3 1.7 µA
V
RUN1,2
RUN Pin ON Threshold V
RUN1
, V
RUN2
Rising
l
1.1 1.22 1.35 V
V
RUN1,2HYS
RUN Pin ON Hysteresis 80 mV
V
SENSE(MAX)
Maximum Current Sense Threshold
(Note 8)
V
FB1,2
= 0.7V, V
SENSE1,2
= 3.3V, I
LIM
= 0V
V
FB1,2
= 0.7V, V
SENSE1,2
= 3.3V, I
LIM
= Float
V
FB1,2
= 0.7V, V
SENSE1,2
= 3.3V, I
LIM
= INTV
CC
l
l
l
20
40
60
30
50
75
40
60
90
mV
mV
mV
TG R
UP
TG Driver Pull-Up On-Resistance TG High 2.6 Ω
TG R
DOWN
TG Driver Pulldown 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 Pulldown On-Resistance BG Low 1.1 Ω
TG1,2 t
r
TG1,2 t
f
TG Transition Time:
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
25
25
ns
ns
BG1,2 t
r
BG1,2 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 C
LOAD
= 3300pF Each Driver 30 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time C
LOAD
= 3300pF Each Driver 30 ns
t
ON(MIN)
Minimum On-Time (Note 7) 90 ns
INTV
CC
Linear Regulator
V
INTVCC
Internal V
CC
Voltage 7V < V
IN
< 24V 4.8 5 5.2 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0mA to 50mA 0.5 2 %
V
EXTVCC
EXTV
CC
Switchover Voltage EXTV
CC
Ramping Positive
l
4.5 4.7 V
V
LDO
EXT EXTV
CC
Voltage Drop I
CC
= 20mA, V
EXTVCC
= 5V 50 100 mV
V
LDOHYS
EXTV
CC
Hysteresis 200 mV
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C, V
IN
= 15V, V
RUN1,2
= 5V, unless otherwise noted.