LT3640 Datasheet, PDF (3/24 Pages) Linear Technology – Dual Monolithic Buck Regulator with Power-On Reset and Watchdog Timer

LT3640
ELECTRICAL CHARACTERISTICS 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.
PARAMETER
CONDITIONS
MIN TYP MAX UNITS
V_IN Undervoltage Lockout Threshold
V_IN Undervoltage Release Threshold
V_IN Overvoltage Lockout Threshold
V_IN Overvoltage Release Threshold
Quiescent Current from V_IN
EN/UVLO = 0.3V
Not Switching
l
3.6
4
V
l
3.8
4.2
V
l 35
36.5
38
V
l 34
35.5
37
V
0.1
1
μA
275
375
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 1.75
2
2.35
MHz
l 450
500
550
kHz
FB1 Voltage
l 1.24 1.265 1.29
V
FB1 Bias Current
FB1 = 1.265V
30
100
nA
FB1 Line Regulation
SW1 Minimum Off-Time
5V < V_IN < 30V
0.001
%/V
70
ns
SW1 V_CESAT
SW1 Leakage Current
I_SW1 = 800mA
400
mV
0.1
1
μA
SW1 Current Limit
FB1 = 1V (Note 3)
FB1 = 0.1V
l 2.2
2.8
3.3
A
1.8
A
DA Current limit
FB1 = 1V (Note 4)
FB1 = 0.1V
l 1.1
1.35
1.7
A
0.8
A
BST Pin Current
Minimum BST-SW Voltage
I_SW1 = 800mA
30
50
mA
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
V_IN2 Maximum Operating Voltage
EN2 Threshold Voltage
l
2.3
2.5
V
l
5.5
V
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
SW2 Minimum Off-Time
2.5V < V_IN2 < 5.5V
0.01
%/V
70
ns
SW2 PMOS Current Limit
(Note 5)
l 1.5
1.9
2.2
A
SW2 NMOS Current Limit
(Note 5)
l 0.9
1.1
1.3
A
SW2 PMOS R_DS(ON)
SW2 NMOS R_DS(ON)
ΔFB2 to Enable PGOOD
ΔFB2 Hysteresis to Disable PGOOD
PGOOD Voltage
I_SW2 = 0.5A (Note 6)
I_SW2 = 0.5A (Note 6)
FB2 = 0.6V, I_PGOOD = 1mA
275
mΩ
200
mΩ
20
40
80
mV
20
40
80
mV
200
320
mV
3640p
3