LM19

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SNIS122E – MAY 2001 – REVISED MARCH 2013

Capacitive Loads

The LM19 handles capacitive loading well. Without any precautions, the LM19 can drive any capacitive load less

than 300 pF as shown in Figure 3. Over the specified temperature range the LM19 has a maximum output

impedance of 160

Ω. 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 4. In a noisy environment it may even be necessary to add a capacitor from the output to ground

with a series resistor as shown in Figure 4. A 1

μF output capacitor with the 160 Ω maximum output impedance

and a 200

Ω series resistor will form a 442 Hz lowpass filter. Since the thermal time constant of the LM19 is

much slower, the overall response time of the LM19 will not be significantly affected.

Figure 3. LM19 No Decoupling Required for Capacitive Loads Less than 300 pF

Table 3. LM19 with Filter for Noisy Environment

and Capacitive Loading greater than 300 pF

R (

Ω)

C (µF)

200

1

470

0.1

680

0.01

1 k

0.001

Either placement of resistor as shown

above is just as effective.

Figure 4. LM19 with Filter for Noisy Environment

and Capacitive Loading greater than 300 pF

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