SYNC/MODE Voltage . ................................................6V
Operating Junction Temperature Range (Note 2)
LT8641E ............................................. –40°C to 125°C
LT8641I .............................................. –40°C to 125°C
LT8641H ............................................ –40°C to 150°C
Storage Temperature Range .................. –65°C to 150°C
20 19 18
BIAS 1
INTV
CC
2
BST 3
V
IN1
4
GND1 6
UDC PACKAGE
18-LEAD (3mm
×
4mm) PLASTIC QFN
θ
JA
= 40°C/W,
θ
JC(PAD
) = 12°C/W (NOTE 3)
EXPOSED PAD (PINS 21, 22) ARE SW, SHOULD BE SOLDERED TO PCB
NOTE: PINS 5 AND 12 ARE REMOVED. CONFIGURATION DOES
NOT
MATCH
JEDEC 20-LEAD PACKAGE OUTLINE
ORDER INFORMATION
LEAD FREE FINISH
LT8641EUDC#PBF
LT8641IUDC#PBF
LT8641HUDC#PBF
TAPE AND REEL
LT8641EUDC#TRPBF
LT8641IUDC#TRPBF
LT8641HUDC#TRPBF
PART MARKING*
LGSN
LGSN
LGSN
PACKAGE DESCRIPTION
18-Lead (3mm × 4mm) Plastic QFN
18-Lead (3mm × 4mm) Plastic QFN
18-Lead (3mm × 4mm) Plastic QFN
TEMPERATURE RANGE
–40°C to 125°C
–40°C to 125°C
–40°C to 150°C
Contact the factory for parts specified with wider operating temperature ranges. *The temperature grade is identified by a label on the shipping container.
Tape and reel specifications.
Some packages are available in 500 unit reels through designated sales channels with #TRMPBF suffix.
ELECTRICAL CHARACTERISTICS
PARAMETER
Minimum Input Voltage
V
IN
Quiescent Current
V
EN/UV
= 0V
CONDITIONS
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
MIN
l
l
GND
PG
FB
TYP
2.6
0.75
0.75
1.7
1.7
0.3
17
200
MAX
3.0
3
10
4
10
0.5
50
350
0.816
0.822
0.03
UNITS
V
µA
µA
µA
µA
mA
µA
µA
V
V
%/V
Rev B
V
EN/UV
= 2V, Not Switching, V
SYNC
= 0V
l
V
EN/UV
= 2V, Not Switching, V
SYNC
= 2V
V
IN
Current in Regulation
Feedback Reference Voltage
Feedback Voltage Line Regulation
V
OUT
= 0.8V, V
IN
= 6V, Output Load = 100µA
V
OUT
= 0.8V, V
IN
= 6V, Output Load = 1mA
V
IN
= 6V, I
LOAD
= 0.5A
V
IN
= 6V, I
LOAD
= 0.5A
V
IN
= 4.0V to 42V, I
LOAD
= 0.5A
l
l
l
l
0.804
0.79
0.81
0.81
0.004
2
For more information
www.analog.com
LT8641
ELECTRICAL CHARACTERISTICS
PARAMETER
Feedback Pin Input Current
BIAS Pin Current Consumption
Minimum On-Time
Minimum Off-Time
Oscillator Frequency
R
T
= 221k
R
T
= 60.4k
R
T
= 18.2k
I
SW
= 1A
l
l
l
l
The
l
denotes the specifications which apply over the full operating
temperature range, otherwise specifications are at T
A
= 25°C.
CONDITIONS
V
FB
= 1V
V
BIAS
= 3.3V, 2MHz
I
LOAD
= 1.5A, SYNC = 0V
I
LOAD
= 1.5A, SYNC = 2V
l
l
MIN
–20
TYP
9
35
35
80
MAX
20
50
50
110
240
735
2.15
9.9
7.25
15
1.07
20
UNITS
nA
mA
ns
ns
ns
kHz
kHz
MHz
mΩ
A
mΩ
A
µA
V
mV
nA
%
%
%
nA
Ω
V
V
V
%
kHz
180
665
1.85
6.2
4.8
–15
210
700
2.00
105
8.2
55
5.8
1.01
45
Top Power NMOS On-Resistance
Top Power NMOS Current Limit
Bottom Power NMOS On-Resistance
Bottom Power NMOS Current Limit
SW Leakage Current
EN/UV Pin Threshold
EN/UV Pin Hysteresis
EN/UV Pin Current
PG Upper Threshold Offset from V
FB
PG Lower Threshold Offset from V
FB
PG Hysteresis
PG Leakage
PG Pull-Down Resistance
SYNC/MODE Threshold
V
INTVCC
= 3.4V, I
SW
= 1A
V
INTVCC
= 3.4V
V
IN
= 42V, V
SW
= 0V, 42V
EN/UV Rising
V
EN/UV
= 2V
V
FB
Falling
V
FB
Rising
V
PG
= 3.3V
V
PG
= 0.1V
SYNC/MODE DC and Clock Low Level Voltage
SYNC/MODE Clock High Level Voltage
SYNC/MODE DC High Level Voltage
R
T
= 60.4k, V
SYNC
= 3.3V
l
l
l
l
0.95
–20
5
–5.25
–40
7.5
–8
0.4
10.25
–10.75
40
750
0.7
2.3
0.9
1.2
2.6
22
2.5
2000
1.4
2.9
Spread Spectrum Modulation
Frequency Range
TR/SS Source Current
TR/SS Pull-Down Resistance
Spread Spectrum Modulation Frequency V
SYNC
= 3.3V
l
1.2
1.9
220
2.6
µA
Ω
Fault Condition, TR/SS = 0.1V
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 LT8641E is guaranteed to meet performance specifications
from 0°C to 125°C junction temperature. Specifications over the –40°C
to 125°C operating junction temperature range are assured by design,
characterization, and correlation with statistical process controls. The
LT8641I is guaranteed over the full –40°C to 125°C operating junction
temperature range. The LT8641H is guaranteed over the full –40°C to
150°C operating junction temperature range. High junction temperatures
degrade operating lifetimes. Operating lifetime is derated at junction
temperatures greater than 125°C.
The junction temperature (T
J
, in °C) is calculated from the ambient
temperature (T
A
in °C) and power dissipation (PD, in Watts) according to
the formula:
T
J
= T
A
+ (PD •
θ
JA
)
where
θ
JA
(in °C/W) is the package thermal impedance.
Note 3:
θ
values determined per JEDEC 51-7, 51-12. See Applications
Information section for information on improving the thermal resistance
and for actual temperature measurements of a demo board in typical
operating conditions.
Note 4:
This IC includes overtemperature protection that is intended to
protect the device during overload conditions. Junction temperature will
exceed 150°C when overtemperature protection is active. Continuous
operation above the specified maximum operating junction temperature
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