LT8495_15 Datasheet, PDF (1/34 Pages) Linear Technology – SEPIC/Boost Converter with 2A, 70V Switch, 9A Quiescent Current, POR and Watchdog Timer

LT8495
FEATURES
SEPIC/Boost Converter with
2A, 70V Switch, 9µA Quiescent
Current, POR and Watchdog Timer
DESCRIPTION
n _{Wide Input Voltage Range of ~1V to 60V}
(2.5V to 32V for Start-Up)
n _{Low Ripple Burst Mode}^® _Operation
n _{9µA IQ at 12VIN to 5.0VOUT}
n _{Output Ripple (<10mV Typ.)}
n _{Dual Supply Pins:}
n _{Improves Efficiency}
n _{Reduces Minimum Supply Voltage to ~1V after}
Start-Up to Extend Battery Life
n _{Integrated 2A/70V Power Switch}
n _{Programmable Watchdog Timer Can Operate When}
V_IN Supply Is Removed
n _{Programmable Power-On Reset Timer (POR) with}
RST Functional for Input Supply Down to 1.3V
n _{FMEA Fault Tolerant in TSSOP Package}
n _{Fixed Frequency PWM, SEPIC/BOOST/FLYBACK}
Topologies
n _{Programmable Switching Frequency:}
250kHz to 1.5MHz
n _{UVLO Programmable on SWEN and RSTIN Pins}
n _{Soft-Start Programmable with One Capacitor}
n _{Small 20-Lead QFN or 20-Lead TSSOP Packages}
APPLICATIONS
n _{Automotive ECU Power}
n _{Power for Portable Products}
n _{Industrial Supplies}
The LT^®8495 is an adjustable frequency (250kHz to 1.5MHz)
monolithic switching regulator with a power-on reset and
watchdog timer. Quiescent current can be less than 9µA
when operating and is ~0.3µA when SWEN, WDE and RSTIN
are low. Configurable as a SEPIC, boost or flyback con-
verter, the low ripple Burst Mode operation maintains high
efficiency at low output current while keeping output
ripple below 10mV. Dual supply pins (V_IN and BIAS) allow
the part to automatically operate from the most efficient
supply. Input supply voltage can be up to 60V for SEPIC
topologies and up to 32V (with ride-through up to 60V)
for boost and flyback topologies. After start-up, battery
life is extended since the part can draw current from its
output (BIAS) even when V_IN voltage drops below 2.5V.
The reset and watchdog timeout periods are independently
adjustable using external capacitors. Using a resistor divider
on the SWEN pin provides a programmable undervoltage
lockout (UVLO) for the converter. A resistor divider connected
to RSTIN provides UVLO control that asserts the RST pin.
Additional features such as frequency foldback and soft-
start are integrated. Fault tolerance in the TSSOP allows
for adjacent pin shorts or an open without raising the
output voltage above its programmed value. The LT8495
is available in 20-lead QFN and 20-lead TSSOP packages
with exposed pads 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
450kHz, 5V Output SEPIC Converter
V_IN
3V TO 60V
2.2µF
• ^15µH
2.2µF
15µH
•
1nF
4.7nF
1µF
169k
SW
BIAS
V_IN
SWEN
RSTIN
FB
LT8495
CWDT
CPOR
GND
SS
WDO
RT
WDE
RST
WDI
1M _4.7pF
8.87k
316k
47µF
×2
V_OUT
5V
0.35A (V_IN = 3V)
0.6A (V_IN = 5V)
1.0A (V_IN >12V)
µC
8495 TA01a
No-Load Supply Current
25
20
15
10
WATCHDOG ENABLED
5
WATCHDOG DISABLED
0
0
12
24
36
48
60
INPUT VOLTAGE (V)
8495 TA01b
For more information www.linear.com/LT8495
Efficiency
90
85
V_IN = 24V
80
V_IN = 12V
75
V_IN = 5V
70
65
60
0.0
0.2
0.4
0.6
0.8
1.0
LOAD CURRENT (A)
8495 TA01c
8495fa
1