LMC8101 Datasheet, PDF (16/26 Pages) National Semiconductor (TI) – Rail-to-Rail Input and Output, 2.7V Op Amp in micro SMD package with Shutdown

LMC8101
SNOS496F – AUGUST 2000 – REVISED MARCH 2013
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CONVERSION BOARDS
In order to ease the evaluation of tiny packages such as the DSBGA, there is a conversion board
(LMC8101CONV) available to board designers. This board converts a DSBGA device into an 8 pin DIP package
(see Figure 56) for easier handling and evaluation. This board can be ordered from Texas Instruments by
contacting http://www.ti.com.
Figure 56. DSBGA Conversion Board pin-out
INCREASED OUTPUT CURRENT
Compared to the LMC7101, the LMC8101 has an improved output stage capable of up to three times larger
output sourcing and sinking current. This improvement would allow a larger output voltage swing range
compared to the LMC7101 when connected to relatively heavy loads. For lower supply voltages this is an added
benefit since it increases the output swing range. For example, the LMC8101 can typically swing 2.5Vpp with
2mA sourcing and sinking output current (Vs = 2.7V) whereas the LMC7101 output swing would be limited to
1.9Vpp under the same conditions. Also, compared to the LMC7101 in the SOT-23 package, the LMC8101 can
dissipate more power because both the VSSOP and the DSBGA packages have 40% better heat dissipation
capability.
LOWER 1/f NOISE
The dominant input referred noise term for the LMC8101 is the input noise voltage. Input noise current for this
device is of no practical significance unless the equivalent resistance it looks into is 5MΩ or higher.
The LMC8101's low frequency noise is significantly lower than that of the LMC7101. For example, at 10Hz, the
input referred spot noise voltage density is 85 nV√Hz as compared to about 200nV√Hz for the LMC7101. Over a
frequency range of 0.1Hz to 100Hz, the total noise of the LMC8101 will be approximately 60% less than that of
the LMC7101.
LOWER THD
When connected to heavier loads, the LMC8101 has lower THD compared to the LMC7101. For example, with
5V supply at 10KHz and 2Vpp swing (Av = −2), the LMC8101 THD (0.2%) is 60% less than the LMC7101's. The
LMC8101 THD can be kept below 0.1% with 3Vpp at the output for up to 10KHz (refer to the Typical
Performance Characteristics plots).
IMPROVING THE CAP LOAD DRIVE CAPABILITY
This can be accomplished in several ways:
• Output resistive loading increase:
The Phase Margin increases with increasing load (refer to the Typical Performance Characteristics plots). When
driving capacitive loads, stability can generally be improved by allowing some output current to flow through a
load. For example, the cap load drive capability can be increased from 8200pF to 16000pF if the output load is
increased from 5kΩ to 600Ω (A_V = +10, 25% overshoot limit, 10V supply).
• Isolation resistor between output and cap load:
16
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