Datasheet
2
LT1681
1681f
Supply Voltages
Power Supply (V
CC
)............................. –0.3V to 20V
Topside Supply (V
BST
)................... V
BSTREF
– 0.3V to
V
BSTREF
+ 20V (V
BST(MAX)
= 90V)
Topside Reference Pin (V
BSTREF
).......... –0.6V to 75V
Input Voltages
SHDN Pin .................................. –0.3V to V
CC
+ 0.3V
All Other Inputs ..................... –0.3V to 5V
REF
+ 0.3V
Maximum Currents
5V
REF
Pin........................................ –85mA to 10mA
FSET Pin ............................................. –2mA to 5mA
All Other Inputs .................................. –2mA to 2mA
Operating Ambient Temperature Range
LT1681E (Note 4) .............................. –40°C to 85°C
LT1681I ............................................. –40°C to 85°C
Storage Temperature Range ................ –65°C to 150°C
Lead Temperature (Soldering, 10 sec)................. 300°C
(Note 1)
ORDER PART
NUMBER
LT1681ESW
LT1681ISW
T
JMAX
= 125°C, θ
JA
= 85°C/W
The ● denotes specifications which apply over the full operating temperature range, otherwise specifications are T
A
= 25°C.
V
CC
= V
BST
= 12V, V
BSTREF
= 0V, V
VC
= 2V, V
FB
= V
REF
= 1.25V, C
TG
= C
BG
= C
SG
= 1000pF.
ABSOLUTE MAXIMUM RATINGS
W
WW
U
PACKAGE/ORDER INFORMATION
W
U
U
ELECTRICAL CHARACTERISTICS
1
2
3
4
5
6
7
8
9
10
TOP VIEW
SW PACKAGE
20-LEAD PLASTIC SO
20
19
18
17
16
15
14
13
12
11
SHDN
OVLO
THERM
SGND
5V
REF
FSET
SYNC
SS
V
FB
V
C
V
BST
TG
BSTREF
BLKSENS
BG
PWRGND
V
CC
SG
I
MAX
SENSE
SYMBOL PARAMETER CONDITIONS MIN TYP MAX UNITS
Supply and Protection
V
CC
Operating Supply Voltage Range ● 91218 V
I
CC
DC Active Supply Current (Note 2) 17 22 mA
● 25 mA
DC Active UVL Supply Current V
SHDN
> 1.35V, V
CC
= 8V ● 800 1200 µA
DC Standby Supply Current V
SHDN
< 0.3V 0.5 µA
I
BST
DC Active Supply Current TG Logic High (Note 2) ● 5 8.5 mA
DC Standby Supply Current V
SHDN
< 0.3V 0.1 µA
V
SHDN
Shutdown Rising Threshold ● 1.15 1.25 1.35 V
Shutdown Threshold Hysteresis ● 100 150 200 mV
I
SS
Soft-Start Charge Current V
SS
= 2V ● –14 –10 –6 µA
V
SS
Soft-Start Reset Threshold 225 mV
V
CCUVLO
Undervoltage Lockout Threshold Falling Edge ● 8.0 8.40 8.60 V
Rising Edge
● 8.3 8.75 8.95 V
Undervoltage Lockout Hysteresis ● 0.25 0.35 V
V
BSTUVLO
Boost Undervoltage Lockout Falling Edge ● 5.7 6.4 7.1 V
(V
BST
-BSTREF) Rising Edge ● 6.5 7.0 7.5 V
Boost UVLO Hysteresis ● 0.3 0.6 V
Consult LTC Marketing for parts specified with wider operating temperature ranges.