LTC3878_15 Datasheet, PDF (3/26 Pages) Linear Technology – Fast, Wide Operating Range No RSENSE Step-Down DC/DC Controller

LTC3878
Electrical Characteristics The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T_A = 25°C. V_IN = 15V unless otherwise noted.
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
t_OFF(MIN)
V_SENSE(MAX)
Minimum Off-Time
Valley Current Sense Threshold
V_PGND – V_SW
Peak Current = Valley + Ripple
I_ON = 30µA
V_RNG = 1V, V_FB = 0.76V
V_RNG = 0V, V_FB = 0.76V
V_RNG = INTV_CC, V_FB = 0.76V
220
300
ns
l 108
133
165
mV
l 74
93
119
mV
l 152
186
224
mV
V_SENSE(MIN)
V_RUN/SS
Minimum Current Sense Threshold
V_PGND – V_SW
Forced Continuous Operation
RUN/SS Pin On Threshold
V_RNG = 1V, V_FB = 0.84V
V_RNG = 0V, V_FB = 0.84V
V_RNG = INTV_CC, V_FB = 0.84V
V_RUN/SS Rising
–67
mV
–47
mV
–93
mV
1.4
1.5
1.6
V
Soft-Start Charging Current
V_RUN/SS = 0V
–1.2
µA
INTV_CC(UVLO)
INTV_CC(UVLOR)
INTV_CC Undervoltage Lockout
INTV_CC Undervoltage Lockout Release
TG Driver Pull-Up On-Resistance
Falling
Rising
TG High
l
3.3
3.9
V
l
3.6
4
V
2.5
Ω
TG Driver Pull-Down On-Resistance TG Low
1.2
Ω
BG Driver Pull-Up On-Resistance
BG High
2.5
Ω
BG Driver Pull-Down On-Resistance BG Low
0.7
Ω
TG/BG t_1D
TG Rise Time
TG Fall Time
BG Rise Time
BG Fall Time
Top Gate Off to Bottom Gate On Delay
Synchronous Switch-On Delay Time
C_LOAD = 3300pF (Note 5)
C_LOAD = 3300pF (Note 5)
C_LOAD = 3300pF (Note 5)
C_LOAD = 3300pF (Note 5)
C_LOAD = 3300pf Each Driver (Note 5)
20
ns
20
ns
20
ns
20
ns
15
ns
TG/BG t_2D
Bottom Gate Off to Top Gate On Delay C_LOAD = 3300pf Each Driver (Note 5)
Synchronous Switch-On Delay Time
15
ns
Internal V_CC Regulator
Internal V_CC Voltage
6V < V_IN < 38V
5.15
5.3
5.45
V
Internal V_CC Load Regulation
I_CC = 0mA to 20mA
–0.1
±2
%
PGOOD Output
PGOOD Upper Threshold
PGOOD Lower Threshold
PGOOD Hysteresis
V_FB Rising
V_FB Falling
V_FB Returning
5.5
7.5
9.5
%
–5.5 –7.5 –9.5
%
2
3.5
%
PGOOD Low Voltage
I_PGOOD = 5mA
0.15
0.4
V
PGOOD Turn-On Delay
12
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 as follows:
T_J = T_A + (P_D • 110°C/W)
Note 3: The LTC3878 is tested in a feedback loop that adjusts V_FB to
achieve a specified error amplifier output voltage (I_TH).
Note 4: The LTC3878E is guaranteed to meet specifications from
0°C to 85°C. Specifications over the –40°C to 85°C operating temperature
range are assured by design, characterization and correlation with
statistical process controls. The LTC3878I is guaranteed to meet
specifications over the full –40°C to 85°C operating temperature range.
Note 5: Rise and fall time are measured using 10% and 90% levels. Delay
times are measured using 50% levels.
3878fa