LT8697_15 Datasheet, PDF (1/30 Pages) Linear Technology – USB 5V 2.5A Output, 42V Input Synchronous Buck with Cable Drop Compensation

LT8697
USB 5V 2.5A Output,
42V Input Synchronous Buck with
Cable Drop Compensation
FEATURES
n _{Wide Input Range: 5V to 42V}
n _{Low Dropout Under All Conditions: 450mV at 2.1A}
n _{Accurate 5V Output: ±1.3% Over Full Temperature}
Range
n _{Programmable Cable Drop Compensation}
n _{Programmable Output Current Limit}
n _{Output Current Monitor}
n _{Dual Input Feedback Permits Regulation on Output}
of USB Switch
n _{Forced Continuous Mode for Fast Load Step}
Response
n _{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
n _{Fast Minimum Switch-On Time: 45ns}
n _{Adjustable Output from 5.0V to 5.25V}
n _{Adjustable and Synchronizable: 300kHz to 2.2MHz}
n _{Small Thermally Enhanced 3mm × 5mm 24-Lead}
QFN Package
APPLICATIONS
n _{Automotive and Industrial USB}
n _{Precision 5V Supply}
DESCRIPTION
The LT^®8697 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 main-
tain accurate 5V regulation at the USB socket connected
to the end of a long cable. Forced continuous operation
allows the LT8697 to sink current, further enhancing ac-
curate 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.
TYPICAL APPLICATION
2MHz 5V Step-Down Converter with Cable Drop Compensation
V_IN
6V TO 42V
4.7µF
1µF
10nF
16.5k
V_IN
BST
EN/UV
PG
INTV_CC
ICTRL
SYNC
TR/SS
RT
SW
LT8697 ^SYS
ISP
ISN
USB5V
RCBL
GND PGND
0.1µF
3.3µH
47µF
×2
18.2k
V_OUT
0.018Ω
3 METERS AWG 20
TWISTED PAIR CABLE
0.1Ω
1nF
10k
+
V_LOAD
5V, 2.4A
–
0.1Ω
8697 TA01a
For more information www.linear.com/LT8697
Transient Response Through 3 Meters
AWG 20 Twisted-Pair Cable
5.50
5
5.25
4
V_OUT
5.00
3
V_LOAD
4.75
2
I_LOAD
50mA/µs
4.50
1
4.25
100µs/DIV
0
8697 TA01b
8697fb
1