LTC3618_15 Datasheet, PDF (4/24 Pages) Linear Technology – Dual 4MHz, 3A Synchronous Buck Converter for DDR Termination

LTC3618
Electrical Characteristics 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.
SYMBOL
V_MODE
(Note 8)
PGOOD1
PGOOD2
t_PGOOD
R_PGOOD
V_RUN
PARAMETER
CONDITIONS
V_MODE High Voltage
V_MODE Low Voltage
Power Good Voltage Window of
V_DDQ
Power Good Voltage Window of V_TT
Power Good Blanking Time
Pulse-Skipping Mode
Forced Continuous Mode
TRACK/SS1 = SV_IN, Entering Window
V_FB1 Ramping Up
V_FB1 Ramping Down
TRACK/SS1 = SV_IN, Leaving Window
V_FB1 Ramping Up
V_FB1 Ramping Down
Entering Window
V_TT Ramping Up
V_TT Ramping Down
Leaving Window
V_FB2 Ramping Up
V_FB2 Ramping Down
Entering/Leaving Window
Power Good Pull-Down On-Resistance I = 10mA
V_RUN Voltage
Input High
Input Low
Pull-Down Resistance
MIN
TYP
1.0
–5
2
5
8
–10.5
–8
–5
2.5
5
8
–10.5
–8
65
105
8
12
l
1
l
4
MAX UNITS
V
0.4
V
–2
%
%
10.5
%
%
–2.5
%
%
10.5
%
%
140
µs
30
Ω
V
0.4
V
MΩ
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 forced 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.
3618fc
4
For more information www.linear.com/LTC3618