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

LTC3615
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, R_SRLIM = 40.2k, unless
otherwise specified (Notes 1, 2, 11).
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
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
(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
SV_IN – 0.3
UNITS
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 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3615E 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 LTC3615I is guaranteed to meet specifications over the
full –40°C to 125°C operating junction temperature range. Note that
the maximum ambient temperature is determined by specific operating
conditions in conjunction with board layout, the rated package thermal
resistance and other environmental factors. 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 impedence.
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 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.
3615f