LTC3788_15 Datasheet, PDF (4/32 Pages) Linear Technology – 2-Phase, Dual Output Synchronous Boost Controller

LTC3788
Electrical Characteristics The l denotes the specifications which apply over the full operating
junction temperature range, otherwise specifications are at T_A = 25°C, VBIAS = 12V, unless otherwise noted (Note 2).
SYMBOL
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
t_ON(MIN)
Minimum BG On-Time
INTV_CC Linear Regulator
V_INTVCCVIN
Internal V_CC Voltage
V_LDOVIN
INTV_CC Load Regulation
V_INTVCCEXT
Internal V_CC Voltage
V_LDOEXT
INTV_CC Load Regulation
V_EXTVCC
EXTV_CC Switchover Voltage
V_LDOHYS
EXTV_CC Hysteresis
Oscillator and Phase-Locked Loop
(Note 7)
6V < VBIAS < 38V, V_EXTVCC = 0V
I_CC = 0mA to 50mA, V_EXTVCC = 0V
V_EXTVCC = 6V
I_CC = 0mA to 40mA, V_EXTVCC = 6V
EXTV_CC Ramping Positive
110
ns
5.2
5.4
5.6
V
0.5
2
%
5.2
5.4
5.6
V
0.5
2
%
4.5
4.8
5
V
250
mV
f_PROG
Programmable Frequency
f_LOW
Lowest Fixed Frequency
f_HIGH
Highest Fixed Frequency
f_SYNC
Synchronizable Frequency
PGOOD1 and PGOOD2 Outputs
R_FREQ = 25k
R_FREQ = 60k
R_FREQ = 100k
V_FREQ = 0V
V_FREQ = INTV_CC
PLLIN/MODE = External Clock
105
kHz
335
400
465
kHz
760
kHz
320
350
380
kHz
485
535
585
kHz
l 75
850
kHz
V_PGL
I_PGOOD
V_PG
PGOOD Voltage Low
PGOOD Leakage Current
PGOOD Trip Level
I_PGOOD = 2mA
0.2
0.4
V
V_PGOOD = 5V
±1
µA
V_FB with Respect to Set Regulated Voltage
V_FB Ramping Negative
–12
–10
–8
%
Hysteresis
2.5
%
V_FB Ramping Positive
Hysteresis
8
10
12
%
2.5
%
t_PGOOD(DELAY) PGOOD Delay
BOOST1 and BOOST2 Charge Pump
PGOOD Going High to Low
25
µs
I_BOOST1,2
BOOST Charge Pump Available
Output Current
V_SW1,2 = 12V; V_BOOST1,2 – V_SW1,2 = 4.5V;
FREQ = 0V, Forced Continuous or
Pulse-Skipping Mode
55
µA
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 LTC3788 is tested under pulsed load conditions such that T_J
≈ T_A. The LTC3788E is guaranteed to meet specifications from 0°C to 85°C
junction temperature. Specifications over the –40°C to 125°C operating
junction temperature range are assured by design, characterization and
correlation with statistical process controls. The LTC3788I is guaranteed
over the –40°C to 125°C operating junction temperature range. Note that
the maximum ambient temperature consistent with these specifications
is determined by specific operating conditions in conjunction with board
layout, the rated package thermal impedance and other environmental
factors. The junction temperature (T_J, in °C) is calculated from the ambient
temperature (T_A, in °C) and power dissipation (P_D, in Watts) according to
the formula: T_J = T_A + (P_D • θ_JA), where θ_JA = 34°C/W.
4
Note 3: 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 device reliability or permanently damage
the device.
Note 4: The LTC3788 is tested in a feedback loop that servos V_FB to the
output of the error amplifier while maintaining I_TH at the midpoint of the
current limit range.
Note 5: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency.
Note 6: Rise and fall times are measured using 10% and 90% levels.
Delay times are measured using 50% levels.
Note 7: See Minimum On-Time Considerations in the Applications
Information section.
3788fc