LM20

SNIS106P – DECEMBER 1999 – REVISED FEBRUARY 2013

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Table 3. Temperature Rise of LM20 Due to Self-Heating and Thermal Resistance (

(1)

SC70-5

SC70-5

No Heat Sink

Small Heat Sink

(°C/W)

(°C)

(°C/W)

(°C)

Still air

412

0.2

350

0.19

Moving air

312

0.17

266

0.15

(1)

See PCB Layouts Used For Thermal Measurements for PCB layout samples.

DSBGA

DSBGA

No Heat Sink

Small Heat Sink

(°C/W)

(°C)

(°C/W)

(°C)

Still air

340

0.18

TBD

TBD

Moving air

TBD

TBD

TBD

TBD

Capacitive Loads

The LM20 handles capacitive loading well. Without any precautions, the LM20 can drive any capacitive load less

than 300 pF as shown in Figure 6. Over the specified temperature range the LM20 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

shown in Figure 7. 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 7. 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 LM20 is

much slower, the overall response time of the LM20 will not be significantly affected.

Figure 6. LM20 No Decoupling Required for Capacitive Loads Less Than 300 pF

R (

Ω)

C (µF)

200

1

470

0.1

680

0.01

1 k

0.001

8

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