LTC1438_15 Datasheet, PDF (4/32 Pages) Linear Technology – Dual High Efficiency, Low Noise, Synchronous Step-Down Switching Regulators

LTC1438/LTC1439
ELECTRICAL CHARACTERISTICS The ● denotes the specifications which apply over the full operating
temperature range. T_A = 25°C, V_IN = 15V, V_RUN/SS1,2 = 5V unless otherwise noted.
SYMBOL
PARAMETER
Low-Battery Comparator
V_SATLBO
LBO Saturation Voltage
I_LLBO
LBO Leakage
V_THLB1
LBI Trip Voltage
I_INLB1
LBI Input Current
V_HYSLBO
LBO Hysteresis
Auxiliary Regulator/Comparator
I_AUXDR
AUXDR Current
Max Current Sinking Capability
Control Current
Leakage when OFF
I_INAUXFB
I_INAUXON
V_THAUXON
V_SATAUXDR
V_AUXFB
AUXFB Input Current
AUXON Input Current
AUXON Trip Voltage
AUXDR Saturation Voltage
AUXFB Voltage
V_THAUXDR
AUXFB Divider Disconnect Voltage
CONDITIONS
I_LBO = 1.6mA, V_LBI = 1.1V
V_LBO = 12V, V_LBI = 1.4V
High to Low Transition on LBO
V_LBI = 1.19V
V_EXTVCC = 0V
V_AUXDR = 4V, V_AUXFB = 1.0V, V_AUXON = 5V
V_AUXDR = 5V, V_AUXFB = 1.5V, V_AUXON = 5V
V_AUXDR = 24V, V_AUXFB = 1.5V, V_AUXON = 0V
V_AUXFB = 1.19V, V_AUXON = 5V
V_AUXON = 5V
V_AUXDR = 4V, V_AUXFB = 1V
I_AUXDR = 1.6mA, V_AUXFB = 1V, V_AUXON = 5V
V_AUXON = 5V, 11V < V_AUXDR < 24V (Note 6)
V_AUXON = 5V, 3V < V_AUXDR < 7V
V_AUXON = 5V (Note 6); Ramping Negative
MIN TYP MAX UNITS
0.6
1
V
●
0.01
1
µA
● 1.16 1.19 1.22
V
●
1
50
nA
20
mV
10
15
mA
1
5
µA
0.01
1
µA
0.01
1
µA
0.01
1
µA
1.0 1.19 1.4
V
0.4
0.8
V
● 11.5 12.0 12.5
V
● 1.14 1.19 1.24
V
7.5
8.5
9.5
V
Note 1: Absolute Maximum Ratings are those values beyond which the life
of the device may be impaired.
Note 2: T_J is calculated from the ambient temperature T_A and power
dissipation P_D according to the following formulas:
LTC1438CG, LTC1439CG: T_J = T_A + (P_D)(95°C/W)
LTC1439CGW: T_J = T_A + (P_D)(85°C/W)
Note 3: The LTC1438 and LTC1439 are tested in a feedback loop which
servos V_OSENSE1,2 to the balance point for the error amplifier
(V_ITH1,2 = 1.19V).
Note 4: Dynamic supply current is higher due to the gate charge being
delivered at the switching frequency. See Applications Information.
Note 5: Oscillator frequency is tested by measuring the C_OSC charge and
discharge current (I_OSC) and applying the formula:
f_OSC (kHz) = 8.4(10⁸)[C_OSC (pF) + 11]^–1 (1/I_CHG + 1/I_DISC) ^–1
Note 6: The auxiliary regulator is tested in a feedback loop which servos
V_AUXFB to the balance point for the error amplifier. For applications with
V_AUXDR > 9.5V, V_AUXFB uses an internal resistive divider. See Applications
Information section.
Note 7: The LTC1439EG is guaranteed to meet performance specifications
from 0°C to 70°C. Specifications over the –40°C to 85°C operating
temperature range are assured by design, characterization and correlation
with statistical process controls.
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