LM56_15 Datasheet, PDF (11/22 Pages) Texas Instruments – LM56 Dual Output Low Power Thermostat

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V_REF AND V_TEMP CAPACITIVE LOADING
LM56
SNIS120G – APRIL 2000 – REVISED FEBRUARY 2013
Figure 16. Loading of V_REF and V_TEMP
The LM56 V_REF and V_TEMP outputs handle capacitive loading well. Without any special precautions, these outputs
can drive any capacitive load as shown in Figure 16.
NOISY ENVIRONMENTS
Over the specified temperature range the LM56 V_TEMPoutput has a maximum output impedance of 1500Ω. In an
extremely noisy environment it may be necessary to add some filtering to minimize noise pickup. It is
recommended that 0.1 μF be added from V⁺ to GND to bypass the power supply voltage, as shown in Figure 16.
In a noisy environment it may be necessary to add a capacitor from the V_TEMP output to ground. A 1 μF output
capacitor with the 1500Ω output impedance will form a 106 Hz lowpass filter. Since the thermal time constant of
the V_TEMP output is much slower than the 9.4 ms time constant formed by the RC, the overall response time of
the V_TEMP output will not be significantly affected. For much larger capacitors this additional time lag will increase
the overall response time of the LM56.
APPLICATIONS CIRCUITS
Figure 17. Reducing Errors Caused by Bias Current
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