LTC3868 Datasheet, PDF (4/38 Pages) Linear Technology – Low IQ, Dual 2-Phase Synchronous Step-Down Controller

LTC3868
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 = 12V, V_RUN1,2 = 5V, EXTV_CC = 0V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN TYP MAX UNITS
INTV_CC Linear Regulator
V_INTVCCVIN Internal V_CC Voltage
6V < V_IN < 24V, V_EXTVCC = 0V
4.85
5.1
5.35
V
V_LDOVIN
V_INTVCCEXT
V_LDOEXT
V_EXTVCC
INTV_CC Load Regulation
Internal V_CC Voltage
INTV_CC Load Regulation
EXTV_CC Switchover Voltage
I_CC = 0mA to 50mA, V_EXTVCC = 0V
6V < V_EXTVCC < 13V
I_CC = 0mA to 50mA, V_EXTVCC = 8.5V
EXTV_CC Ramping Positive
0.7
1.1
%
4.85
5.1
5.35
V
0.6
1.1
%
4.5
4.7
4.9
V
V_LDOHYS
EXTV_CC Hysteresis
250
mV
Oscillator and Phase-Locked Loop
f_25kΩ
f_65kΩ
f_105kΩ
f_LOW
Programmable Frequency
Programmable Frequency
Programmable Frequency
Low Fixed Frequency
R_FREQ = 25k, PLLIN/MODE = DC Voltage
R_FREQ = 65k, PLLIN/MODE = DC Voltage
R_FREQ = 105k, PLLIN/MODE = DC Voltage
V_FREQ = 0V, PLLIN/MODE = DC Voltage
105
kHz
375 440 505
kHz
835
kHz
320 350 380
kHz
f_HIGH
High Fixed Frequency
V_FREQ = INTV_CC, PLLIN/MODE = DC Voltage
485 535 585
kHz
f_SYNC
Synchronizable Frequency
PGOOD1 and PGOOD2 Outputs
PLLIN/MODE = External Clock
l 75
850
kHz
V_PGL
I_PGOOD
V_PG
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
Hysteresis
0.2
0.4
V
±1
µA
–13
–10
–7
%
2.5
%
V_FB with Respect to Set Regulated Voltage
V_FB Ramping Positive
Hysteresis
7
10
13
%
2.5
%
t_PG
Delay for Reporting a Fault (PGOOD Low)
25
µs
Note 1: Stresses beyond those listed under Absolute Maximum Ratings
may cause permanent damage to the device. Exposure to any Absolute
Maximum Ratings for extended periods may affect device reliability and
lifetime.
Note 2: The LTC3868E is guaranteed to meet performance 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 LTC3868I is guaranteed over the full
–40°C to 85°C operating temperature range.
Note 3: T_J is calculated from the ambient temperature T_A and power
dissipation P_D according to the following formula:
T_J = T_A + (P_D • 34°C/W)
Note 4: The LTC3868 is tested in a feedback loop that servos V_ITH1,2 to a
specified voltage and measures the resultant V_FB1,2.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications information.
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).
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