LTC3615-1_15 Datasheet, PDF (4/32 Pages) Linear Technology – Dual 4MHz, 3A Synchronous Step-Down DC/DC Converter

LTC3615/LTC3615-1
Electrical Characteristics The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T_A = 25°C (Note 2), SV_IN = PV_INx = 3.3V, R_T = 178k, R_SRLIM = 40.2k, unless
otherwise specified.
SYMBOL
j_SW1–SW2
V_SRLIM
V_MODE
(Note 9)
PGOOD
t_PGOOD
R_PGOOD
V_RUN
PARAMETER
CONDITIONS
Output Phase Shift Between SW1
and SW2 (LTC3615)
Output Phase Shift Between SW1
and SW2 (LTC3615-1)
Voltage at SRLIM to Enable DDR
Mode
V_PHASE < 0.15 • SV_IN
0.35 • SV_IN < V_PHASE < 0.65 • SV_IN
V_PHASE > 0.85 • SV_IN
V_PHASE < 0.65 • SV_IN
V_PHASE > 0.85 • SV_IN
(Note 9)
Internal Burst Mode Operation
Pulse-Skipping Mode
Forced Continuous Mode
External Burst Mode Operation
Power Good Voltage Windows
Power Good Blanking Time
TRACK/SSx = SV_IN, Entering Window
V_FBx Ramping Up
V_FBx Ramping Down
TRACK/SSx = SV_IN, Leaving Window
V_FBx Ramping Up
V_FBx Ramping Down
Entering/Leaving Window
Power Good Pull-Down On-Resistance I = 10mA
Enable Pin
Input High
Input Low
Pull-Down Resistance
MIN TYP MAX
0
90
180
140
180
SV_IN – 0.3
UNITS
Deg
Deg
Deg
Deg
Deg
V
SV_IN – 0.3
1.1
0.5
0.3
V
V
SV_IN • 0.58
V
0.85
V
–3.5 –6
%
3.5
6
%
9
11
%
–9
–11
%
70
105
140
µs
8
12
30
Ω
l
1
l
V
0.4
V
4
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 LTC3615/LTC3615-1 are tested under pulsed load conditions
such that T_J ≈ T_A. The LTC3615E/LTC3615E-1 are 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 LTC3615I/LTC3615I-1
are guaranteed to meet specifications over the –40°C to 125°C operating
junction temperature range. The LTC3615H/LTC3615H-1 are guaranteed
to meet specifications over the –40°C to 150°C operating temperature
range. The LTC3615MP/LTC3615MP-1 are tested and guaranteed to meet
specifications over the full –55°C to 150°C operating junction temperature
range. High junction temperatures degrade operating lifetime; operating
lifetime is derated for junction temperatures greater than 125°C. 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 impedance 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_FB1,2 to
the midpoint for the error amplifier (V_ITH1,2 = 0.75V).
Note 4: External compensation on ITH pin.
Note 5: Tying the ITH pin to SV_IN enables internal compensation and AVP
mode for the selected channel.
Note 6: Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 7: See description of the TRACK/SS pin in the Pin Functions section.
Note 8: 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 9: See description of the MODE pin in the Pin Functions section.
Note 10: Guaranteed by design and correlation to wafer level
measurements for QFN packages.
Note 11: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed 150°C when overtemperature protection is active.
Continuous operation above the specified maximum operating junction
temperature may impair device reliability or permanently damage the
device.
3615fb
4
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