LTC1540_15 Datasheet, PDF (9/12 Pages) Linear Technology – Nanopower Comparator with Reference

LTC1540
TYPICAL APPLICATIONS
Low-Battery Detect
Figure 9 shows how to use the LTC1540 for a low-battery
detect, drawing only 1.4µA at V_BAT = 2V. The circuit is
powered by a 2-cell NiCd battery. The V_BAT pin could be as
low as 1.6V when the batteries are completely depleted.
The electrical specifications of the LTC1540 guarantee
operation down to a supply voltage of 2V, but it is still
functional with the supply as low as 1.6V. Some param-
eters, such as V_REF and V_OS, will be degraded on lower
supply voltages. The input voltage range extends from
0.9V below the positive supply to the negative supply.
R1
3M
R2
1.1M
3 IN⁺
4 IN^–
V_BAT = ~1.6V TO 2.5V
7
V ⁺ _LTC1540
+
OUT 8
LBO
–
2-CELL
NiCd
6 REF
R3
40k
5 HYST
R4
1.2M
R5
1M
V^– GND
2
1
1540 F09
Figure 9. Low-Battery Detect Works Down to 1.6V
sn1540 1540fas
9