Datasheet

LTC3851-1
3
38511fa
ELECTRICAL CHARACTERISTICS
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
IN
Input Operating Voltage Range 4 38 V
V
FB
Regulated Feedback Voltage I
TH
= 1.2V (Note 4)
l
0.792 0.800 0.808 V
I
FB
Feedback Current (Note 4) –10 –50 nA
V
REFLNREG
Reference Voltage Line Regulation V
IN
= 6V to 38V (Note 4) 0.002 0.02 %/V
V
LOADREG
Output Voltage Load Regulation (Note 4)
Measured in Servo Loop,
∆I
TH
= 1.2V to 0.7V
l
0.01 0.1 %
(Note 4)
Measured in Servo Loop,
∆I
TH
= 1.2V to 1.6V
l
–0.01 –0.1 %
g
m
Transconductance Amplifi er g
m
I
TH
= 1.2V, Sink/Source = 5µA (Note 4) 2 mmho
g
m
GBW Transconductance Amp Gain Bandwidth I
TH
= 1.2V 3 MHz
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 5)
V
RUN
= 5V
V
RUN
= 0V
1
20 35
mA
µA
UVLO Undervoltage Lockout on INTV
CC
V
INTVCC
Ramping Down 3.25 V
UVLO Hys UVLO 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 ±1 ±2 µA
I
TK/SS
Soft-Start Charge Current V
TK/SS
= 0V 0.6 1 2 µA
V
RUN
RUN Pin On Threshold V
RUN
Rising
l
1.10 1.25 1.35 V
V
RUNHYS
RUN Pin On Hysteresis 130 mV
V
SENSE(MAX)
Maximum Current Sense Threshold V
FB
= 0.7V, V
SENSE
= 3.3V
l
40 50 65 mV
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
TG t
r
TG t
f
TG Transition Time
Rise Time
Fall Time
(Note 6)
C
LOAD
= 3300pF
C
LOAD
= 3300pF
25
25
ns
ns
BG tr
BG tf
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
Bottom Switch-On Delay Time
C
LOAD
= 3300pF Each Driver
(Note 6)
30 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF Each Driver
(Note 6)
30 ns
t
ON(MIN)
Minimum On-Time (Note 7) 90 ns
INTV
CC
Linear Regulator
V
INTVCC
Internal V
CC
Voltage 6V < V
IN
< 38V 4.8 5 5.2 V
V
LDO
INT INTV
CC
Load Regulation I
CC
= 0mA to 50mA 0.5 %
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency R
FREQ
= 60k 480 500 530 kHz
f
LOW
Lowest Frequency R
FREQ
= 160k 220 250 280 kHz
The l denotes the specifi cations which apply over the full operating
junction temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN
= 15V, V
RUN
= 5V unless otherwise noted.