Datasheet

LTC3618
4
3618fc
For more information www.linear.com/LTC3618
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
V
MODE
(Note 8)
V
MODE
High Voltage Pulse-Skipping Mode 1.0 V
V
MODE
Low Voltage Forced Continuous Mode 0.4 V
PGOOD1 Power Good Voltage Window of
V
DDQ
TRACK/SS1 = SV
IN
, Entering Window
V
FB1
Ramping Up
V
FB1
Ramping Down 2
–5
5
–2 %
%
TRACK/SS1 = SV
IN
, Leaving Window
V
FB1
Ramping Up
V
FB1
Ramping Down –10.5
8
–8
10.5 %
%
PGOOD2 Power Good Voltage Window of V
TT
Entering Window
V
TT
Ramping Up
V
TT
Ramping Down 2.5
–5
5
–2.5 %
%
Leaving Window
V
FB2
Ramping Up
V
FB2
Ramping Down –10.5
8
–8
10.5 %
%
t
PGOOD
Power Good Blanking Time Entering/Leaving Window 65 105 140 µs
R
PGOOD
Power Good Pull-Down On-Resistance I = 10mA 8 12 30 Ω
V
RUN
V
RUN
Voltage Input High
Input Low
l
l
1
0.4
V
V
Pull-Down Resistance 4 MΩ
elecTrical characTerisTics
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 LTC3618 is tested under pulsed load conditions such that
T
J
≈ T
A
. The LTC3618E is guaranteed to meet performance specifications
over the 0°C to 85°C operating junction temperature range. Specifications
over the –40°C to 125°C operating junction temperature range are
assured by design, characterization and correlation with statistical process
controls. The LTC3618I is guaranteed to meet specifications over the
full –40°C to 125°C operating junction temperature range. Note that the
maximum ambient temperature consistent with these specifications is
determined by specific operating conditions in conjunction with board
layout, the rated package thermal resistance and other environmental
factors. The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
, in °C) and power dissipation (P
D
, in watts) according to
the formula:
T
J
= T
A
+ (P
D
• θ
JA
)
where θ
JA
(in °C/W) is the package thermal impedance.
Note 3: This parameter is tested in a feedback loop which servos V
FB1
to
the midpoint for the error amplifier (V
ITH1
= 0.75V).
Note 4: External compensation on ITH pin.
Note 5: Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 6: See description of the TRACK/SS pin in the Pin Functions section.
Note 7: When sourcing current, the average output current is defined
as flowing out of the SW pin. When sinking
current, the average output
current is defined as flowing into the SW pin. Sinking mode requires the
use of for
ced continuous mode.
Note 8: See description of the MODE pin in the Pin Functions section.
Note 9: Guaranteed by design and correlation to wafer level measurements
for QFN packages.
Note 10: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 125°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability or permanently damage the
device.
The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T
A
= 25°C (Note 2), SV
IN
= PV
INx
= 3.3V, R
T
= 178k, unless otherwise
specified.