Datasheet

LTC3851A
3
3851afa
elecTrical characTerisTics
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Main Control Loops
V
IN
Operating Input Voltage Range
l
4 38 V
V
FB
Regulated Feedback Voltage I
TH
= 1.2V (Note 4) 0°C to 85°C
I
TH
= 1.2V (Note 4) –40°C to 125°C
I
TH
= 1.2V (Note 4) –40°C to 150°C
I
TH
= 1.2V (Note 4) –55°C to 150°C
l
l
l
l
0.792
0.788
0.788
0.788
0.800 0.808
0.812
0.812
0.812
V
V
V
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
(Note 4) Measured in Servo Loop,
∆I
TH
= 1.2V to 0.7V (H-Grade, MP-Grade)
l
l
0.01 0.1
0.2
%
%
(Note 4) Measured in Servo Loop,
∆I
TH
= 1.2V to 1.6V
(Note 4) Measured in Servo Loop,
∆I
TH
= 1.2V to 1.6V (H-Grade, MP-Grade)
l
l
–0.01 –0.1
–0.2
%
%
g
m
Transconductance Amplifier g
m
I
TH
= 1.2V, Sink/Source = 5µA (Note 4) 2 mmho
g
m
GBW Transconductance Amp Gain Bandwidth I
TH
= 1.2V (Note 8) 3 MHz
I
Q
Input DC Supply Current
Normal Mode
Shutdown
(Note 5)
V
RUN
= 5V
V
RUN
= 0V
1.2
25 50
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 V
FB
with Respect to Set Regulated Voltage V
FB
Ramping
Positive (OV)
7.5 10 12.5 %
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 1.22 1.35 V
V
RUNHYS
RUN Pin On—Hysteresis 120 mV
V
SENSE(MAX)
Maximum Current Sense Threshold V
FB
= 0.7V, V
SENSE
= 3.3V, I
LIM
= 0V
V
FB
= 0.7V, V
SENSE
= 3.3V, I
LIM
= 0V (H-/MP-Grade)
V
FB
= 0.7V, V
SENSE
= 3.3V, I
LIM
= Float
V
FB
= 0.7V, V
SENSE
= 3.3V, I
LIM
= Float (H-/MP-Grade)
V
FB
= 0.7V, V
SENSE
= 3.3V, I
LIM
= INTV
CC
V
FB
= 0.7V, V
SENSE
= 3.3V, I
LIM
= INTV
CC
(H-/MP-Grade)
l
l
l
l
l
l
20
15
40
35
65
60
30
53
80
40
45
65
70
95
100
mV
mV
mV
mV
mV
mV
TG R
UP
TG Driver Pull-Up On-Resistance TG High 2.2 Ω
TG R
DOWN
TG Driver Pull-Down On-Resistance TG Low 1.2 Ω
BG R
UP
BG Driver Pull-Up On-Resistance BG High 2.1 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 T
ransition 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
The l denotes the specifications which apply over the specified operating
temperature range, otherwise specifications are at T
A
= 25°C (Note 2). V
IN
= 15V, V
RUN
= 5V unless otherwise noted.