LTC3446EDE Datasheet, PDF (4/20 Pages) Linear Technology – Monolithic Buck Regulator with Dual VLDO Regulators

LTC3446
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 LTC3446 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3446E is guaranteed to meet performance specifications
from 0°C to 85°C operating 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 LTC3446I is guaranteed to meet performance specifications over
the –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 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: Minimum operating V_IN voltage required for the VLDO regulators
to stay in regulation is:
V_IN ≥ LV_OUT(MAX) + 1.4V and V_IN ≥ 2.7V
Note 4: Dynamic supply current is higher due to the internal gate charge
being delivered at the switching frequency.
Note 5: The LTC3446 is tested in a feedback loop that connects the
BUCKFB pin to the output of the buck converter’s error amplifier (i.e., the
I_TH pin).
Note 6: Minimum operating LV_IN voltage required for the VLDO regulators
to stay in regulation is:
LV_IN ≥ L_VOUT(MAX) + 100mV and LV_IN ≥ 0.9V
Note 7: Operating conditions are limited by maximum junction
temperature. The regulated output voltage specification will not apply
for all possible combinations of input voltage and output current. When
operating at maximum input voltage, the output current range must be
limited. When operating at maximum output current, the input voltage
range must be limited.
Note 8: PGOOD assertion indicates that the feedback voltages of all
enabled supplies are within the specified percentage of their target values.
Note 9: Dropout voltage in the DFN package is assured by design,
characterization and statistical process control.
Typical Performance Characteristics
Buck Regulated Feedback Voltage
vs Temperature
808
806
804
802
800
798
796
V_IN = 2.7V
V_IN = 3.6V
794
V_IN = 4.2V
V_IN = 5.5V
792
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
3446 G01
LDO1 Regulated Feedback
Voltage vs Temperature
408
406
404
402
400
398
396
V_IN = 2.7V
V_IN = 3.6V
394
V_IN = 4.2V
V_IN = 5.5V
392
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
3446 G02
LDO2 Regulated Feedback
Voltage vs Temperature
408
406
404
402
400
398
396
V_IN = 2.7V
V_IN = 3.6V
394
V_IN = 4.2V
V_IN = 5.5V
392
–50 –30 –10 10 30 50 70 90 110 130
TEMPERATURE (°C)
3446 G03
3446ff
4