LPC660AIM National Semiconductor, LPC660AIM Datasheet - Page 11

• Manufacturer Part Number: LPC660AIM
• Description: IC,Operational Amplifier,QUAD,CMOS,SOP,14PIN,PLASTIC
• Manufacturer: National Semiconductor

Specifications of LPC660AIM

• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant

Application Hints
(Input pins are lifted out of PC board and soldered directly to components.
All other pins connected to PC board.)
BIAS CURRENT TESTING
The test method of Figure 7 is appropriate for bench-testing
bias current with reasonable accuracy. To understand its op-
eration, first close switch S2 momentarily. When S2 is
opened, then
Typical Single-Supply Applications
Note: A 5V bias on the photodiode can cut its capacitance by a factor of 2
or 3, leading to improved response and lower noise. However, this bias on
the photodiode will cause photodiode leakage (also known as its dark
current).
Photodiode Current-to-Voltage Converter
FIGURE 6. Air Wiring
(Continued)
DS010547-17
DS010547-24
(V
Note: (Upper limit of output range dictated by input common-mode range;
lower limit dictated by minimum current requirement of LM385.)
11
+
= 5.0 V
A suitable capacitor for C2 would be a 5 pF or 10 pF silver
mica, NPO ceramic, or air-dielectric. When determining the
magnitude of I
must be taken into account. Switch S2 should be left shorted
most of the time, or else the dielectric absorption of the ca-
pacitor C2 could cause errors.
Similarly, if S1 is shorted momentarily (while leaving S2
shorted)
where C
FIGURE 7. Simple Input Bias Current Test Circuit
DC
x
)
Micropower Current Source
is the stray capacitance at the + input.
−
, the leakage of the capacitor and socket
DS010547-18
DS010547-25
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