Datasheet
LT3570
3
3570fb
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.
PARAMETER CONDITIONS MIN TYP MAX UNITS
Minimum Operating Voltage (V
IN1
) (Note 3)
l
2.1 2.5 V
Minimum Operating Voltage (V
IN2
) (Note 3)
l
2.1 2.5 V
Shutdown Current (Note 4) V
SHDN1,2,3
= 0V 0 1.5 µA
V
IN1
Quiescent Current V
SHDN1
= 12V, V
SHDN2,3
= 0V, V
C1
= 0.4V (Not Switching)
V
SHDN1
= 0V, V
SHDN2,3
= 12V
3.2
65
4.5
150
mA
µA
V
IN2
Quiescent Current V
SHDN1,3
= 0V, V
SHDN2
= 12V, V
C2
= 0.4V (Not Switching)
V
SHDN1,3
= 12V, V
SHDN2
= 0V
3.5
3.5
4.5
4.5
mA
mA
V
IN3
Quiescent Current V
SHDN1,2
= 0V, V
SHDN3
= 12V
V
SHDN1,2
= 12V, V
SHDN3
= 0V
700
0
950
1.5
µA
µA
Bias Quiescent Current V
BIAS
= 2.5V 2.3 3.1 mA
V
SHDN1,2,3
Pin Threshold I
VIN2
> 100µA 0.3 1.4 V
V
SHDN1,2,3
Pin UVLO
l
1.1 1.25 1.4 V
V
SHDNX
Pin Current V
SHDNX
= 12V, V
SHDNY,Z
= 0V (Note 5)
V
SHDN1,2,3
= 0V
30
0.1
50
1.5
µA
µA
Switching Frequency R
T
= 44.2k
R
T
= 7.87k
450
1900
500
2100
550
2300
kHz
kHz
Maximum Duty Cycle R
T
= 44.2k
R
T
= 7.87k
95
80
%
%
Synchronous Frequency Threshold 0.3 1.5 V
Synchronous Frequency Range 650 2750 kHz
Synchronous Frequency Minimum On/Off
Time
50 ns
FB1,2,3 Pin Voltage
l
772 788 804 mV
FB1,2,3 Pin Voltage Line Regulation V
VIN1,2,3
= 2.5V to 36V, V
C1,2
= 1V 0.01 %/V
FB1,2 Pin Bias Current V
FB1,2
= 800mV, V
C1,2
= 1V (Note 6) 30 200 nA
FB3 Pin Bias Current V
FB3
= 800mV (Note 6) 30 200 nA
SS1,2 Pin Source Current V
SS1,2
= 500mV 4.5 µA
V
C1,2
Pin Source Current V
FB1,2
= 600mV 12 µA
V
C1,2
Pin Sink Current V
FB1,2
= 1V 12 µA
SW1
Error Amplifi er 1 Transconductance 190 µMho
Error Amplifi er 1 Voltage Gain 100 V/V
V
C1
Pin Switching Threshold 750 mV
V
C1
to SW1 Current Gain 5.9 A/V
SW1 Current Limit (Note 7) 1.5 2.4 3.1 A
SW1 V
CESAT
I
SW1
= 1A (Note 7) 240 mV
SW1 Leakage Current SW1 = 40V, V
SHDN1
= 0V 0.2 5 µA