LTC1998_15 Datasheet, PDF (1/12 Pages) Linear Technology – 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, LTM, Linear Technology and the Linear logo 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
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