Rainbow Electronics LM61 - Manual (Page 6)

1.0 Mounting
(Continued)
2.0 Capacitive Loads
The LM61 handles capacitive loading well. Without any spe-
cial precautions, the LM61 can drive any capacitive load as
shown in Figure 4. Over the specified temperature range the
LM61 has a maximum output impedance of 5 k
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
S
to GND to bypass the power
supply voltage, as shown in Figure 5. In a noisy environment
it may be necessary to add a capacitor from the output to
ground. A 1 µF output capacitor with the 5 k
Ω maximum
output impedance will form a 32 Hz lowpass filter. Since the
thermal time constant of the LM61 is much slower than the 5
ms time constant formed by the RC, the overall response
time of the LM61 will not be significantly affected. For much
larger capacitors this additional time lag will increase the
overall response time of the LM61.
SOT-23* SOT-23** TO-92* TO-92***
no heat sink small heat fin no heat sink small heat fin
θ
JA
T
J
− T
A
θ
JA
T
J
− T
A
θ
JA
T
J
− T
A
θ
JA
T
J
− T
A
(˚C/W) (˚C) (˚C/W) (˚C) (˚C/W) (˚C) (˚C/W) (˚C)
Still air 450 0.26 260 0.13 180 0.09 140 0.07
Moving air 180 0.09 90 0.05 70 0.03
*Part soldered to 30 gauge wire.
**Heat sink used is 1 ⁄ 2 " square printed circuit board with 2 oz. foil with part attached as shown in Figure 2.
***Part glued and leads soldered to 1" square of 1/16" printed circuit board with 2oz. foil or similar.
FIGURE 3. Temperature Rise of LM61 Due to
Self-Heating and Thermal Resistance ( θ
JA
)
01289715
FIGURE 4. LM61 No Decoupling Required for
Capacitive Load
01289716
FIGURE 5. LM61 with Filter for Noisy Environment
LM61
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