LTC1998_1 Datasheet, PDF (1/12 Pages) Linear Technology – 2.5μA, 1% Accurate SOT-23 Comparator and Voltage Reference for Battery Monitoring

LTC1998
FEATURES
2.5µA, 1% Accurate
SOT-23 Comparator and Voltage
Reference for Battery Monitoring
DESCRIPTION
n _{High Accuracy Trip Voltage: 1% Max Error Using}
External 1% Resistors
n _{Adjustable Threshold Voltage and Hysteresis}
n _{Quiescent Current: 2.5μA Typ}
n _{Output Swings Rail-to-Rail}
n _{Thresholds Programmable from 2.5V to 3.25V}
n _{Output State Guaranteed for VBATT ≥1.5V}
n _{Low Profile (1mm) ThinSOT™ Package}
APPLICATIONS
n _{Lithium-Ion Battery-Powered Equipment}
PDAs
Cell Phones
Handheld Instruments
Battery Packs
Pagers
Palm Top Computers
POS Terminals
L, LT, LTC and LTM are registered trademarks of Linear Technology Corporation. ThinSOT is
a trademark of Linear Technology Corporation. All other trademarks are the property of their
respective owners.
The LTC^®1998 is a micropower comparator and a precision
adjustable reference in a 6-pin SOT-23 package that is
optimized for lithium-ion low battery detection circuits.
The LTC1998 features a voltage detection circuit with an
adjustable threshold voltage and hysteresis. The threshold
voltage can be programmed from 2.5V to 3.25V with two
external resistors. A 10mV to 750mV hysteresis can be
added with a third external resistor.
A proprietary internal architecture maintains 1% thresh-
old voltage accuracy over temperature with low cost 1%
external resistors.
A separate power supply pin, V_LOGIC, allows the battery-low
logic output to operate below the battery voltage, allowing
compatibility with low voltage microprocessors without a
pull-up resistor. Power supply glitches are eliminated by
preventing the cross-conducting current which occurs
when the output changes state.
The LTC1998 operates with battery or supply voltages
up to 5.5V and its battery-low output is valid for battery
voltages above 1.5V.
BLOCK DIAGRAM
BATT
V_HYST.A
V_TH.A
THRESHOLD
ADJUST
1.1R
R
1.2V
V_LOGIC
BATTLO
1998 BD
Threshold Voltage Error vs Temperature
1.0
0.9
0.8
V_TH.A SET BY 1%
EXTERNAL R,
0.7
THRESHOLD = 3V
0.6
0.5 V_TH.A = 1V
THRESHOLD = 3V
0.4
0.3
V_TH.A SHORTED
TO GROUND,
0.2
THRESHOLD = 2.5V
0.1
0
–45 –25
–5 15 35 55
TEMPERATURE (°C)
75 95
1998 TA02
1998fa
1