鈮?/div>
1.5V
Low Profile (1mm) ThinSOT
TM
Package
The LTC
廬
1998 is a micropower comparator and a preci-
sion 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 thresh-
old 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.
APPLICATIO S
s
Lithium-Ion Battery-Powered Equipment
PDAs
Cell Phones
Handheld Instruments
Battery Packs
Pagers
Palm Top Computers
POS Terminals
, LTC and LT are registered trademarks of Linear Technology Corporation.
ThinSOT is a trademark of Linear Technology Corporation.
BLOCK DIAGRA
Threshold Voltage Error vs Temperature
1.0
BATT
V
LOGIC
1.1R
V
HYST.A
V
TH.A
1.2V
% ERROR
THRESHOLD
ADJUST
0.9
0.8
0.7
0.6
0.5
0.4
0.3
0.2
0.1
1998 BD
R
BATTLO
0
鈥?5 鈥?5
U
V
TH.A
SET BY 1%
EXTERNAL R,
THRESHOLD = 3V
V
TH.A
= 1V
THRESHOLD = 3V
V
TH.A
SHORTED
TO GROUND,
THRESHOLD = 2.5V
35
15
55
鈥?
TEMPERATURE (擄C)
75
95
1998
G05
W
U
1998f
1