LTC3853_15 Datasheet, PDF (4/36 Pages) Linear Technology – Triple Output, Multiphase Synchronous Step-Down Controller

LTC3853
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 3), V_IN = 15V, V_RUN1,2,3 = 5V, unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
Bottom Gate Off to Top Gate On Delay (Note 6)
Top Switch-On Delay Time
C_LOAD = 3300pF Each Driver
t_ON(MIN)
Minimum On-Time
(Note 7)
INTV_CC Linear Regulator
V_INTVCC
Internal V_CC Voltage
7V < V_IN < 24V
INTV_CC Load Regulation
I_CC = 0mA to 50mA
V_EXTVCC
EXTV_CC Switchover Voltage
EXTV_CC Ramping Positive
EXTV_CC Voltage Drop
I_CC = 20mA, V_EXTVCC = 5V
EXTV_CC Hysteresis
Oscillator and Phase-Locked Loop
30
ns
90
ns
4.8
5
5.2
V
0.5
2
%
l 4.5 4.7
V
30
75
mV
200
mV
Nominal Frequency
Lowest Frequency
Highest Frequency
Channel 2-Channel 1 Phase
Channel 3-Channel 2 Phase
Channel 1-Channel 3 Phase
V_FREQ = 1.2V
V_FREQ = 0V
V_FREQ ≥ 2.4V
450 500 550
kHz
210 250 290
kHz
670 750 830
kHz
120
Deg
120
Deg
120
Deg
Channel 2-Channel 1 Phase
Channel 3-Channel 2 Phase
Channel 1-Channel 3 Phase
V_FB2 Tied to V_IN Through 200kΩ
180
Deg
60
Deg
120
Deg
MODE/PLLIN Input Resistance
250
kΩ
I_FREQ
Phase Detector Output Current
Sinking Capability
Sourcing Capability
PGOOD Outputs
f_MODE < f_OSC
f_MODE > f_OSC
–13
µA
13
µA
I_PGOOD
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level
I_PGOOD = 2mA
V_PGOOD = 5V
V_FB with Respect to Set Regulated Voltage
V_FB Ramping Negative
V_FB Ramping Positive
0.1 0.3
V
±2
µA
–5 – 7.5 –10
%
5
7.5
10
%
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 junction temperature, T_J, is calculated from the ambient
temperature T_A and power dissipation P_D according to the following
formulas:
LTC3853UJ: T_J = T_A + (P_D • 33°C/W)
Note 3: The LTC3853 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3853E is guaranteed to meet performance specifications
from 0°C to 85°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LTC3853I is guaranteed over the –40°C to 125°C operating junction
temperature range. The LTC3853H is guaranteed over the –40°C to 150°C
operating junction temperature range and the LTC3853MP is tested and
guaranteed over the –55°C to 150°C operating junction temperature range.
High junction temperatures degrade operating lifetimes; operating lifetime
is derated for junction temperatures greater than 125°C. 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.
Note 4: The LTC3853 is tested in a feedback loop that servos V_ITH1,2,3 to a
specified voltage and measures the resultant V_FB1,2,3.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See the Applications Information
section.
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).
3853fc
4
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