Electrical Specifications Subject to Change
LT8697
USB 5V 2.5A Output,
42V Input Synchronous Buck with
Cable Drop Compensation
FeaTures
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DescripTion
The
is a compact, high efficiency, high speed
synchronous monolithic step-down switching regulator
designed to power 5V USB applications. A precise output
voltage and programmable cable drop compensation
maintain accurate 5V regulation at the USB socket at the
end of a long cable. Forced continuous operation allows
the LT8697 to sink current, further enhancing accurate
5V regulation during load transients.
Accurate and programmable output current limit, a power
good indicator pin and an output current monitor pin
improve system reliability and safety, allow the user to
implement latch-off or auto-retry functionality and can
eliminate the need for a USB switch IC. Dual feedback al-
lows regulation on the output of a USB switch and limits
cable drop compensation to a maximum of 5.8V output,
protecting USB devices during fault conditions. Thermal
shutdown provides additional protection by limiting power
dissipation in the IC during an overtemperature fault.
The LT8697 is available in a small 24-lead 3mm × 5mm
package with an exposed pad for low thermal resistance.
L,
LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
of Linear Technology Corporation. All other trademarks are the property of their respective owners.
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Wide Input Range: 5V to 42V
Low Dropout Under All Conditions: 450mV at 2.1A
Accurate 5V Output: ±1.3% Over Full Temperature
Range
Programmable Cable Drop Compensation
Programmable Output Current Limit
Output Current Monitor
Dual Input Feedback Permits Regulation on Output
of USB Switch
Forced Continuous Mode for Fast Load Step
Response
High Efficiency Synchronous Operation at 2MHz:
93% Efficiency at 2.1A, 5V
OUT
from 12V
IN
95% Efficiency at 0.9A, 5V
OUT
from 12V
IN
Fast Minimum Switch-On Time: 70ns
Adjustable Output from 5.0V to 5.25V
Adjustable and Synchronizable: 300kHz to 2.2MHz
Small Thermally Enhanced 3mm × 5mm 24-Lead
QFN Package
Automotive and Industrial USB
Precision 5V Supply
applicaTions
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Typical applicaTion
2MHz 5V Step-Down Converter with Cable Drop Compensation
V
IN
6V TO 42V
4.7µF
V
IN
EN/UV
PG
INTV
CC
1µF
ICTRL
SYNC
TR/SS
10nF
16.5k
RT
GND
LT8697
BST
3.3µH
SW
SYS
ISP
ISN
USB5V
RCBL
PGND
18.2k
0.1Ω
47µF
×2
0.018Ω
0.1µF
V
OUT
3 METERS AWG 20
TWISTED PAIR CABLE
0.1Ω
VOLTAGE (V)
5.25
V
OUT
V
LOAD
4
CURRENT (A)
Transient Response Through 3 Meters
AWG 20 Twisted-Pair Cable
5.50
5
1nF
10k
5.00
3
+
LOAD
V
LOAD
5V, 2.4A
4.75
4.50
I
LOAD
50mA/µs
2
1
–
4.25
8697 TA01a
100µs/DIV
0
8697 TA01b
8697p
For more information
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