LTC3869-2_15 Datasheet, PDF (4/42 Pages) Linear Technology – Dual, 2-Phase Synchronous Step-Down DC/DC Controllers

LTC3869/LTC3869-2
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 2). V_IN = 15V, V_RUN1,2 = 5V unless otherwise noted.
SYMBOL PARAMETER
CONDITIONS
MIN
TYP MAX UNITS
INTV_CC Linear Regulator
V_INTVCC
Internal V_CC Voltage
V_LDO INT INTV_CC Load Regulation
V_EXTVCC
EXTV_CC Switchover Voltage
V_LDOHYS EXTV_CC Hysteresis
V_LDO EXT EXTV_CC Voltage Drop
PGOOD Output
6V < V_IN < 38V
I_CC = 0mA to 20mA
EXTV_CC Ramping Positive
I_CC = 20mA, V_EXTVCC = 5V
4.8
l 4.5
5
5.2
V
0.5
2
%
4.7
V
200
mV
50
100 mV
V_PGL
I_PGOOD
V_PG
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level
Oscillator and Phase-Locked Loop
I_PGOOD = 2mA
V_PGOOD = 5V
V_FB with Respect to Set Output Voltage
V_FB Ramping Negative
V_FB Ramping Positive
0.1
0.3
V
±2
µA
–10
%
10
%
f_NOM
Nominal Frequency
f_LOW
Lowest Frequency
f_HIGH
Highest Frequency
R_MODE/PLLIN MODE/PLLIN Input Resistance
I_FREQ
Frequency Setting Current
On Chip Driver
V_FREQ = 1.2V
V_FREQ = 0V
V_FREQ ≥ 2.4V
450
500
550 kHz
210
250
290 kHz
700
780
850 kHz
250
kΩ
9
10
11
µA
TG R_UP
TG R_DOWN
BG R_UP
BG R_DOWN
TG Pull-Up R_DS(ON)
TG Pull-Down R_DS(ON)
BG Pull-Up R_DS(ON)
BG Pull-Down R_DS(ON)
TG High
TG Low
BG High
BG Low
2.6
Ω
1.5
Ω
2.4
Ω
1.1
Ω
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 LTC3869 is tested under pulsed load conditions such that
T_J ≈ T_A. The LTC3869E 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 LTC3869I 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 3: T_J is calculated from the ambient temperature T_A and power
dissipation P_D according to the following formulas:
LTC3869UFD: T_J = T_A + (P_D • 34°C/W)
LTC3869GN-2: T_J = T_A + (P_D • 80°C/W)
Note 4: The LTC3869 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: 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).
Note 8: Guaranteed by design.
38692fa
4
For more information www.linear.com/LTC3869