AN856 Datasheet, PDF (2/3 Pages) Silicon Laboratories – LOWEST SUPPLY CURRENT FOR BATTERY-POWERED APPLICATIONS

AN856
Substituting the output frequency of 1 Hz and a standard capacitor value of 0.1 μF, the necessary R_C resistance of
7.14 M can be calculated.
In setting the output frequency of both timers, the TS3004 offers an advantage because it only requires one
component instead of the two external components required by the CMOS555.
To compare the supply currents of both timers side-by-side, a few supply voltages were applied while both supply
currents were recorded. Table 1 displays the results.
Table 1. Supply Current per Supply Voltage
Supply Voltage
TS3004
Supply Current
CMOS555
Supply Current
1.5 V
1.9 μA
50 μA
2.5 V
2.0 μA
81 μA
3.3 V
2.3 μA
87 μA
As shown in Table 1, at 1.5 V, the TS3004 consumes a factor of 26 less supply current. With a 2.5 V supply, the
TS3004 consumes a factor of 40 less supply current. With a 3.3 V supply, the TS3004 consumes a factor of 38 less
supply current. In summary, the CMOS555 IC uses much more supply current than can be supported in battery or
portable applications.
For all voltages within its supply range, the TS3004 saves a significant amount of supply current, which can help
extend battery life in battery-powered applications. These applications include ultra-long life, low-frequency
battery-powered/portable applications, such as micropower PWM control, pulse-position modulation control, clock
generation, and sequential timing. The TS3004 can also be used as a low-parts-count micropower oscillator and
compact replacement for crystal and ceramic oscillators.
For additional information, see the following:
TS3004 timer IC
TS3004 data sheet
Silicon Labs’ family of timer ICs
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Rev. 1.0