TS3001 Datasheet, PDF (8/10 Pages) Touchstone Semiconductor Inc – A 1V/1uA Easy-to-Use Resistor-Tuned Silicon Oscillator/Timer

TS3001
APPLICATIONS INFORMATION
Minimizing Power Consumption
To keep the TS3001’s power consumption low,
resistive loads at the FOUT and PWMOUT terminals
increase dc power consumption and therefore should
be as large as possible. Capacitive loads at the
FOUT and PWMOUT terminals increase the
TS3001’s transient power consumption and, as well,
should be as small as possible.
One challenge to minimizing the TS3001’s transient
power consumption is the probe capacitance of
oscilloscopes and frequency counter instruments.
Most instruments exhibit an input capacitance of
15pF or more. Unless buffered, the increase in
transient load current can be as much as 400nA.
To minimize capacitive loading, the technique shown
in Figure 1 can be used. In this circuit, the principle of
series-connected capacitors can be used to reduce
the effective capacitive load at the TS3001’s FOUT
and PWMOUT terminals.
Figure 1: Using an External Capacitor in Series with
Probes Reduces Effective Capacitive Load.
To determine the optimal value for C_EXT once the
probe capacitance is known by simply solving for
C_EXT using the following expression:
1
C _T=
1
1
C_{LOA ( FF)} C_PRO
For example, if the instrument’s input probe
capacitance is 15pF and the desired effective load
capacitance at either or both FOUT and PWMOUT
terminals is to be ≤5pF, then the value of C_EXT should
be ≤7.5pF.
TS3001 Start-up Time
As the TS3001 is powered up, its FOUT terminal
(and PWMOUT terminal, if enabled) is active once
the applied VDD is higher than 0.9 volt. Once the
applied VDD is higher than 0.9 volt, the master
oscillator achieves steady-state operation within
1.2ms.
Current- and Voltage-Controlled Oscillators
The TS3001 can be configured into a
Current-Controlled Oscillator as shown in Figure 2.
Figure 2: Configuring the TS3001 into a
Current-Controlled Oscillator.
With a current source sourcing a current of 223nA to
262nA, FOUT can generate an output signal with a
frequency range of 5.2kHz to 90kHz. In a similar
manner, a Voltage-Controlled Oscillator can be
configured as shown in Figure 3. In this case, a
voltage source sourcing a voltage of 290mV to
341mV can generate an FOUT output signal
frequency range of 5.2kHz to 90kHz as well. It is
recommended to use resistor values with a 1%
tolerance.
Figure 3: Configuring the TS3001 into a
Voltage-Controlled Oscillator.
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