LT3570
4
3570fb
PARAMETER CONDITIONS MIN TYP MAX UNITS
SW2
Error Amplifi er 2 Transconductance 195 µMho
Error Amplifi er 2 Voltage Gain 100 V/V
V
C2
Pin Switching Threshold 700 mV
V
C2
to SW2 Current Gain 5.4 A/V
SW2 Current Limit (Note 7) 1.5 2.4 3.1 A
SW2 V
CESAT
I
SW2
= 1A (Note 7) 240 mV
SW2 Leakage Current SW2 = 0V, V
IN2
= 40V, V
SHDN2
= 0V 0.2 5 µA
BOOST Pin Current I
SW2
= 0.5A
I
SW2
= 1.5A
15
30
mA
mA
LDO
LDO Maximum Output Current V
FB3
= 600mV 10 20 mA
ELECTRICAL CHARACTERISTICS
The l denotes the specifi cations which apply over the full operating
temperature range, otherwise specifi cations are at T
A
= 25°C. V
IN1,2,3
= 12V, V
SHDN1,2,3
= 12V unless otherwise noted.
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 LT3570E is guaranteed to meet performance specifi cations
from 0°C to 125°C junction temperature. Specifi cations over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization and correlation with statistical process controls. The
LT3570I is guaranteed over the full –40°C to 125°C operating junction
temperature range.
Note 3: V
IN2
supplies power for the part. V
IN1
supplies power only to the
boost converter. V
IN3
supplies power only to the LDO Controller.
Note 4: Shutdown current is for each individual input current.
Note 5: Current fl ows into the pin.
Note 6: Current fl ows out of the pin.
Note 7: Switch current limit and switch V
CESAT
guaranteed by design
and/or correlation to static test.
Note 8: This IC includes overtemperature protection that is intended
to protect the device during momentary overload conditions. Junction
temperature will exceed the maximum operating junction temperature
range when overtemperature protection is active. Continuous operation
above the specifi ed maximum operating junction temperature may impair
device reliability.
TYPICAL PERFORMANCE CHARACTERISTICS
Feedback Voltage vs Temperature
Frequency vs Temperature
Soft-Start Current vs Temperature
TEMPERATURE (°C)
–50
0.770
VOLTAGE (V)
0.775
0.780
0.785
0.790
050
100
150
3570 G01
0.795
0.800
–25 25
75
125
TEMPERATURE (°C)
–50
FREQUENCY (kHz)
1500
2000
2500
25 75 150
3570 G02
1000
500
0
–25 0
50
100 125
R
T
= 7.87k
R
T
= 20k
R
T
= 44.2k
TEMPERATURE (°C)
–50
CURRENT (µA)
4.4
4.6
4.8
25 50 75 100 125
3570 G03
4.2
4.0
–25 0 150
3.8
3.6
5.0
