LT8495
SEPIC/Boost Converter with
2A, 70V Switch, 9A Quiescent
Current, POR and Watchdog Timer
FEATURES DESCRIPTION
n
Wide Input Voltage Range of ~1V to 60V
The LT 8495 is an adjustable frequency (250kHz to 1.5MHz)
(2.5V to 32V for Start-Up)
monolithic switching regulator with a power-on reset and
n
Low Ripple Burst Mode Operation
watchdog timer. Quiescent current can be less than 9A
n
9A I at 12V to 5.0V
Q IN OUT when operating and is ~0.3A when SWEN, WDE and RSTIN
n
Output Ripple (<10mV Typ.)
are low. Configurable as a SEPIC, boost or flyback con-
n
Dual Supply Pins:
verter, the low ripple Burst Mode operation maintains high
n
Improves Efficiency
efficiency at low output current while keeping output
n
Reduces Minimum Supply Voltage to ~1V after
ripple below 10mV. Dual supply pins (V and BIAS) allow
IN
Start-Up to Extend Battery Life
the part to automatically operate from the most efficient
n
Integrated 2A/70V Power Switch
supply. Input supply voltage can be up to 60V for SEPIC
n
Programmable Watchdog Timer Can Operate When
topologies and up to 32V (with ride-through up to 60V)
V Supply Is Removed
IN for boost and flyback topologies. After start-up, battery
n
Programmable Power-On Reset Timer (POR) with
life is extended since the part can draw current from its
RST Functional for Input Supply Down to 1.3V
output (BIAS) even when V voltage drops below 2.5V.
IN
n
FMEA Fault Tolerant in TSSOP Package
The reset and watchdog timeout periods are independently
n
Fixed Frequency PWM, SEPIC/BOOST/FLYBACK
adjustable using external capacitors. Using a resistor divider
Topologies
on the SWEN pin provides a programmable undervoltage
n
Programmable Switching Frequency:
lockout (UVLO) for the converter. A resistor divider connected
250kHz to 1.5MHz
to RSTIN provides UVLO control that asserts the RST pin.
n
UVLO Programmable on SWEN and RSTIN Pins
n
Soft-Start Programmable with One Capacitor Additional features such as frequency foldback and soft-
n
Small 20-Lead QFN or 20-Lead TSSOP Packages start are integrated. Fault tolerance in the TSSOP allows
for adjacent pin shorts or an open without raising the
APPLICATIONS
output voltage above its programmed value. The LT8495
is available in 20-lead QFN and 20-lead TSSOP packages
n
Automotive ECU Power
with exposed pads for low thermal resistance.
n
Power for Portable Products
L, LT, LTC, LTM, Linear Technology, the Linear logo and Burst Mode are registered trademarks
n
Industrial Supplies
of Analog Devices, Inc. All other trademarks are the property of their respective owners.
TYPICAL APPLICATION
No-Load Supply Current Efficiency
450kHz, 5V Output SEPIC Converter
25 90
2.2F
15H V
OUT
V
IN
5V 85
V = 24V
3V TO 60V IN
20
0.35A (V = 3V)
IN
47F
2.2F 0.6A (V = 5V)
15H 1M IN
2
4.7pF
80
1.0A (V >12V) V = 12V
IN IN
15
V = 5V
75 IN
8.87k
SW BIAS
10
V RSTIN
IN
70
SWEN FB
WATCHDOG ENABLED
LT8495
316k
CWDT 5
65
GND
1nF CPOR WATCHDOG DISABLED
SS
4.7nF
WDO
1F RT
WDE
0 60
C
0 12 24 36 48 60 0.0 0.2 0.4 0.6 0.8 1.0
169k RST
WDI
INPUT VOLTAGE (V) LOAD CURRENT (A)
8495 TA01a
8495 TA01b 8495 TA01c
8495fb
1
For more information www.linear.com/LT8495
SUPPLY CURRENT (A)
EFFICIENCY (%)LT8495
ABSOLUTE MAXIMUM RATINGS
(Note 1)
V , BIAS Voltage ......................................................60V
CPOR, CWDT, SS Voltage ...........................................3V
IN
SWEN, WDE, RSTIN Voltage .....................................60V
Operating Junction Temperature Range
FB Voltage .................................................................60V
LT8495E, LT8495I (Notes 2, 3) .......... 40C to 125C
SW Voltage ...............................................................70V
LT8495H (Notes 2, 3) ........................ 40C to 150C
WDI, RST, WDO Voltage ..............................................6V
Storage Temperature Range .................. 65C to 150C
RT Voltage ..................................................................6V
Lead Temperature (Soldering, 10 sec)
FE Package .......................................................300C
PIN CONFIGURATION
TOP VIEW
TOP VIEW
BIAS 1
20 SW
FB 2 20 19 18 17 16
19 NC
FB 3
18 V
IN
SS 1 GND
15
NC 4
17 NC
GND
RT 2 14
CPOR 5
16 WDI
21 21
GND 3 13 GND
GND GND
CWDT 6
15 WDO
GND 4 12 SW
RST 7
14 GND
RSTIN 5 11 GND
SS 8
13 WDE
NC 9 6 7 8 9 10
12 SWEN
RT 10
11 RSTIN
FE PACKAGE
UF PACKAGE
20-LEAD PLASTIC TSSOP
20-LEAD (4mm 4mm) PLASTIC QFN
= 38C/W
JA
= 47C/W
JA
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
EXPOSED PAD (PIN 21) IS GND, MUST BE SOLDERED TO PCB
ORDER INFORMATION