Datasheet

LTC3852
3
3852f
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loop (Step-Down Regulator)
V
IN2
Controller Input Voltage Range
l
438V
V
FB
Regulated Feedback Voltage (Note 3); I
TH
Voltage = 1.2V
l
0.790 0.800 0.810 V
I
FB
Feedback Current (Note 3) –10 –50 nA
V
REFLNREG
Reference Voltage Line Regulation (Notes 3, 9); V
IN2
= 6V to 38V 0.002 0.02 %/V
V
LOADREG
Output Voltage Load Regulation (Note 3)
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 0.7V
l
0.01 0.1 %
Measured in Servo Loop;
DI
TH
Voltage = 1.2V to 1.6V
l
–0.01 –0.1 %
g
m
Transconductance Amplifi er g
m
(Note 3); I
TH
= 1.2V;
Sink/Source 5µA
2 mmho
I
Q(VIN2)
Controller Input DC Supply Current (Note 4) V
FB
= 0.9V
(RUN = 3.3V)
1.4 mA
Shutdown Supply Current RUN = 0V 25 50 µA
I
Q(VIN1)
Total Input DC Supply Current (Notes 4, 7) V
FB
= 0.9V
(RUN = SHDN = 3.3V)
7mA
Shutdown Supply Current (Note 7) RUN = SHDN = 0V 5 µA
UVLO Undervoltage Lockout INTV
CC
Ramping Down 3.25 V
Undervoltage Hysteresis 0.4 V
V
OVL
Feedback Overvoltage Lockout Measured at V
FB
l
0.86 0.88 0.90 V
I
SENSE
SENSE Pins Current –2.0 2.0 µA
I
TRACK/SS
Soft-Start Charge Current V
TRACK/SS
= 0V 0.5 1 2 µA
V
RUN
RUN Pin On Threshold V
RUN
Rising
l
1.1 1.22 1.35 V
V
RUN(HYS)
RUN Pin On Hysteresis 130 mV
V
SENSE(MAX)
Maximum Current Sense Threshold V
FB
= 0.7V, V
SENSE
–
= 3.3V
l
40 53 68 mV
TG R
UP
TG Driver Pull-Up On-Resistance TG High 2.2 
TG R
DOWN
TG Driver Pull-Down On-Resistance TG Low 1.2 
BG R
UP
BG Driver Pull-Up On-Resistance BG High 2.1 
BG R
DOWN
BG Driver Pull-Down On-Resistance BG Low 1.1 
TG t
r
TG t
f
Top Gate Rise Time
Top Gate Fall Time
C
LOAD
= 3300pF (Note 5) 25
25
ns
ns
BG t
r
BG t
f
Bottom Gate Rise Time
Bottom Gate Fall Time
C
LOAD
= 3300pF (Note 5) 25
25
ns
ns
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
C
LOAD
= 3300pF (Note 5) 30 ns
BG/TG t
1D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF (Note 5) 30 ns
t
ON(MIN)
Minimum On-Time (Note 6) 90 ns
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C (Note 2), V
IN1
= 3.3V, V
IN2
= 15V, V
RUN
= 3.3V, SHDN = 0V,
MODE/PLLIN = 0V unless otherwise noted.