LTC3811_15 Datasheet, PDF (5/48 Pages) Linear Technology – High Speed Dual, Multiphase Step-Down DC/DC Controller

LTC3811
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T_J = 25°C. V_IN = 12V, MODE/SYNC = 0V, unless otherwise specified.
SYMBOL
PARAMETER
DRV_CC Linear Regulator
V_DRVCC
LDO Regulator Output Voltage
ΔV_DRVCC(LOAD)
DRV_CC Load Regulation
ΔV_DRVCC(LINE)
DRV_CC Line Regulation
V_DRVCC(UVLO)
LDO Regulator Undervoltage Threshold
V_DRVCC(HYST)
LDO Regulator Undervoltage Hysteresis
V_EXTVCC
EXTV_CC Switchover Voltage
V_EXTVCC(HYST)
EXTV_CC Switchover Hysteresis
V_EXTVCC(DROP)
EXTV_CC Voltage Drop
Gate Drivers
t_r (TG1, TG2)
t_f (TG1, TG2)
t_r (BG1, BG2)
t_f (BG1, BG2)
R_DS(ON)(TG)
TG1, TG2
Top Gate Rise Time
Top Gate Fall Time
Bottom Gate Rise Time
Bottom Gate Fall Time
Top Gate Pull-Down NMOS
On-Resistance
R_DS(ON)(BG)
BG1, BG2
Bottom Gate Pull-Down NMOS
On-Resistance
I_PK(TG) TG1, TG2
I_PK(BG) BG1, BG2
t_DEAD1
Top Gate (TG) Peak Source Current
Bottom Gate (BG) Peak Source Current
Bottom Gate Off to Top Gate On
Deadtime
t_DEAD2
Top Gate Off to Bottom Gate On
Deadtime
t_ON(MIN)
Minimum On-Time
CONDITIONS
V_EXTVCC = 0V
I_LOAD = 0mA to 50mA
ΔV_IN = 8.5V to 30V
DRV_CC Rising
I_DRVCC = 20mA, EXTV_CC Rising
I_DRVCC = 20mA
I_DRVCC = 20mA, V_EXTVCC = 5V
C_L = 3300pF (Note 6)
C_L = 3300pF (Note 6)
C_L = 3300pF (Note 6)
C_L = 3300pF (Note 6)
TG to SW
BG to PGND
(Note 6)
(Note 6)
V_COMP = 1.25V (Note 6, 7)
MIN TYP MAX UNITS
● 5.6
6.0
6.4
V
–2.0 –0.5
%
0.01
0.2
%/V
3.7
V
0.56
V
4.5
V
400
mV
100
mV
20
ns
10
ns
20
ns
10
ns
0.9
Ω
0.9
Ω
1.0
A
1.0
A
30
ns
30
ns
65
ns
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. Unless otherwise specified, all voltages are relative
to SGND and all currents are positive into a pin.
Note 2: The LTC3811E is guaranteed to meet performance specifications
from 0°C to 85°C temperature. Specifications over the –40°C to
85°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls.
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 • TBD°C/W)
Note 4: The dynamic input supply current is higher due to power
MOSFET gate charging (Q_G • f_OSC). See Applications Information for more
information.
Note 5: The error amplifiers are measured in a feedback loop using an
external servo operational amplifier that drives the V_FB pin and regulates
V_COMP to be equal to the external control voltage.
Note 6: Guaranteed by design, not subject to test.
Note 7: The minimum on-time condition corresponds to an inductor peak-
to-peak ripple current of 50% of I_MAX. See Applications Information for
more details.
Note 8: The voltage positioning amplifier operates as a transconductance
amplifier, where the input voltages are the SENSE⁺ to SENSE^– potentials
for both channels. The amplifier output current flows through an external
resistor in order to program the amount of voltage droop at full load.
Note 9: The PHASEMODE function is only available in the QFN package.
The 36-lead GW package has a fixed channel 1-to-channel 2 phase
relationship of 180°C and a channel 1-to-CLKOUT phase relationship of
90°C. The version in the 36-lead GW package is therefore optimized for
2- and 4-phase operation.
Note 10: Rise and fall times are measured at 10% and 90% levels.
3811f
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