Datasheet

LT3640
3
3640f
The l denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C. V
IN
= 12V, V
IN2
= 3.3V, EN/UVLO = 12V, EN2 = 3.3V, unless otherwise noted.
elecTrical characTerisTics
PARAMETER CONDITIONS MIN TYP MAX UNITS
V
IN
Undervoltage Lockout Threshold
l
3.6 4 V
V
IN
Undervoltage Release Threshold
l
3.8 4.2 V
V
IN
Overvoltage Lockout Threshold
l
35 36.5 38 V
V
IN
Overvoltage Release Threshold
l
34 35.5 37 V
Quiescent Current from V
IN
EN/UVLO = 0.3V
Not Switching
0.1
275
1
375
µA
µA
EN/UVLO Threshold Voltage 1.2 1.26 1.3 V
EN/UVLO High Bias Current EN/UVLO = Threshold + 60mV 2 µA
EN/UVLO Low Bias Current EN/UVLO = Threshold – 60mV 0.1 µA
SYNC Input Frequency 0.35 2.5 MHz
SYNC Threshold Voltage 0.4 0.8 1 V
Switching Frequency RT = 32.4k
RT = 182k
l
l
1.75
450
2
500
2.35
550
MHz
kHz
FB1 Voltage
l
1.24 1.265 1.29 V
FB1 Bias Current FB1 = 1.265V 30 100 nA
FB1 Line Regulation 5V < V
IN
< 30V 0.001 %/V
SW1 Minimum Off-Time 70 100 ns
SW1 V
CESAT
I
SW1
= 800mA 400 mV
SW1 Leakage Current 0.1 1 µA
SW1 Current Limit FB1 = 1V (Note 3)
FB1 = 0.1V
l
2.2 2.8
1.8
3.4 A
A
DA Current limit FB1 = 1V (Note 4)
FB1 = 0.1V
l
1.35 1.7
1
2.2 A
A
BST Pin Current I
SW1
= 800mA 30 50 mA
Minimum BST-SW Voltage 2 2.7 V
ΔFB1 to Start LV Channel 80 100 130 mV
ΔFB1 Hysteresis to Stop LV Channel 30 50 90 mV
V
IN2
Minimum Operating Voltage
l
2.3 2.5 V
V
IN2
Maximum Operating Voltage
l
5.5 V
EN2 Threshold Voltage 0.3 1 1.5 V
FB2 Voltage
l
588 600 612 mV
FB2 Bias Current FB2 = 0.6V 0 100 nA
FB2 Line Regulation 2.5V < V
IN2
< 5.5V 0.01 %/V
SW2 Minimum Off-Time 70 100 ns
SW2 PMOS Current Limit (Note 5)
l
1.5 1.9 2.2 A
SW2 NMOS Current Limit (Note 5)
l
1.2 1.6 2 A
SW2 PMOS R
DS(ON)
I
SW2
= 0.5A (Note 6) 275 mΩ
SW2 NMOS R
DS(ON)
I
SW2
= 0.5A (Note 6) 200 mΩ
ΔFB2 to Enable PGOOD 20 40 80 mV
ΔFB2 Hysteresis to Disable PGOOD 20 40 80 mV
PGOOD Voltage FB2 = 0.6V, I
PGOOD
= 1mA 200 320 mV