LTC3876_15 Datasheet, PDF (5/48 Pages) Linear Technology – Dual DC/DC Controller for DDR Power with Differential VDDQ Sensing and 50mA VTT Reference

LTC3876
ELECTRICAL CHARACTERISTICS The l denotes the specifications which apply over the specified operating
junction temperature range, otherwise specifications are at T_A = 25°C. V_IN = 15V unless otherwise noted. (Note 3)
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
PGood Output
PGD_OV
PGOOD Overvoltage Threshold
V_OUTSENSE, VTTSNS Rising, with Respect to
Reference Voltage
5
7.5
10
%
PGD_UV
PGOOD Undervoltage Threshold
V_OUTSENSE, VTTSNS Falling, with Respect to
Reference Voltage
–5 –7.5 –10
%
PGD_HYS
PGOOD Threshold Hysteresis
V_OUTSENSE, VTTSNS Returning to Reference
Voltage
2.0
%
V_PGD(LO)
PGOOD Low Voltage
I_PGOOD = 2mA
0.1 0.3
V
t_PGD(FALL)
t_PGD(RISE)
Delay from OV/UV Fault to PGOOD Falling
Delay from OV/UV Recovery to PGOOD
Rising
50
μs
20
μs
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: T_J is calculated from the ambient temperature T_A and power
dissipation P_D according to the following formulas:
LTC3876UHF: T_J = T_A + (P_D • 34°C/W)
LTC3876FE: T_J = T_A + (P_D • 28°C/W)
Note 3: The LTC3876 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3876E is guaranteed to meet performance specifications
from 0°C to 85°C. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization
and correlation with statistical process controls. The LTC3876I is
guaranteed to meet performance specifications over the full –40°C to
125°C operating junction temperature range. The maximum ambient
temperature consistent with these specifications is determined by specific
operating conditions in conjunction with board layout, the package thermal
impedance and other environmental factors.
Note 4: This IC includes overtemperature protection that is intended to
protect the device during momentary overload conditions. The maximum
rated junction temperature will be exceeded when this protection is active.
Continuous operation above the specified absolute maximum operating
junction temperature may impair the device reliability or permanently
damage the device.
Note 5: The LTC3876 is tested in a feedback loop that adjusts
(V_OUTSENSE1+ V_{OUTSENSE1–}) and VTTSNS to achieve specified error
amplifier output voltages (ITH1,2).
Note 6: Delay times are measured using 50% levels.
Note 7: In order to simplify the total system error computation, the
regulated voltage is defined in one combined specification which includes
the effects of line, load and common mode variation. The combined
regulated voltage specification is tested by independently varying line,
load, and common mode, which by design do not significantly affect one
another. For any combination of line, load, and common mode variation,
the regulated voltage should be within the limits specified that are tested in
production to the following conditions:
a. Line: V_IN = 4.5V to 38V, ITH = 1V, V_{OUTSENSE1–} = 0V
b. Load: V_IN = 15V, ITH = 0.5V to 1.9V, V_{OUTSENSE1–} = 0V
c. Common mode: V_IN = 15V, ITH = 1V, to V_{OUTSENSE1–} = ±500mV, (Ch1)
3876f
5