LTC3835
4
3835fe
For more information www.linear.com/LTC3835
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Rating condition for extended periods may affect device
reliability and lifetime.
Note 2: The LTC3835E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process
controls. The LTC3835I is guaranteed to meet
performance specifications over the full –40°C to 85°C operating
temperature range.
Note 3: T
J
is calculated from the ambient temperature T
A
and power
dissipation P
D
according to the following formulas:
LTC3835FE: T
J
= T
A
+ (P
D
• 35°C/W)
LTC3835UFD: T
J
= T
A
+ (P
D
• 37°C/W)
ELECTRICAL CHARACTERISTICS
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
RUN
= 5V unless otherwise noted.
Note 4: The LTC3835 is tested in a feedback loop that servos V
ITH
to a
specified voltage and measures the resultant V
FB
.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching
frequency. See Applications Information.
Note 6: Rise and fall times are measured using 10% and 90% levels.
Delay times are measured using 50% levels.
Note 7: The minimum on-time condition is specified for an inductor
peak-to-peak ripple current ≥40% of I
MAX
(see Minimum On-Time
Considerations in the Applications Information section).
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
TG/BG t
1D
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
C
LOAD
= 3300pF 70 ns
BG/TG t
2D
Bottom Gate Off to Top Gate On Delay
Top Switch-On Delay Time
C
LOAD
= 3300pF 70 ns
t
ON(MIN)
Minimum On-Time (Note 7) 180 ns
INTV
CC
Linear Regulator
V
INTVCCVIN
Internal V
CC
Voltage 8.5V < V
IN
< 30V, V
EXTVCC
= 0V 5 5.25 5.5 V
V
LDOVIN
INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 0V 0.2 1.0 %
V
INTVCCEXT
Internal V
CC
Voltage V
EXTVCC
= 8.5V 7.2 7.5 7.8 V
V
LDOEXT
INTV
CC
Load Regulation I
CC
= 0mA to 20mA, V
EXTVCC
= 8.5V 0.2 1.0 %
V
EXTVCC
EXTV
CC
Switchover Voltage EXTV
CC
Ramping Positive 4.5 4.7 V
V
LDOHYS
EXTV
CC
Hysteresis 0.2 V
Oscillator and Phase-Locked Loop
f
NOM
Nominal Frequency V
PLLLPF
= No Connect 360 400 440 kHz
f
LOW
Lowest Frequency V
PLLLPF
= 0V 220 250 280 kHz
f
HIGH
Highest Frequency V
PLLLPF
= INTV
CC
475 530 580 kHz
f
SYNCMIN
Minimum Synchronizable Frequency PLLIN/MODE = External Clock; V
PLLLPF
= 0V 115 140 kHz
f
SYNCMAX
Maximum Synchronizable Frequency PLLIN/MODE = External Clock; V
PLLLPF
= 2V 650 800 kHz
I
PLLLPF
Phase Detector Output Current
Sinking Capability
Sourcing Capability
f
PLLIN/MODE
< f
OSC
f
PLLIN/MODE
> f
OSC
–5
5
µA
µA
PGOOD Output
V
PGL
PGOOD Voltage Low I
PGOOD
= 2mA 0.1 0.3 V
I
PGOOD
PGOOD Leakage Current V
PGOOD
= 5V ±1 µA
V
PG
PGOOD Trip Level V
FB
with Respect to Set Regulated Voltage
V
FB
Ramping Negative
V
FB
Ramping Positive
–12
8
–10
10
–8
12
%
%
