LMC8101 Datasheet, PDF (15/26 Pages) National Semiconductor (TI) – Rail-to-Rail Input and Output, 2.7V Op Amp in micro SMD package with Shutdown

LMC8101
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APPLICATION NOTES
SNOS496F – AUGUST 2000 – REVISED MARCH 2013
SHUTDOWN FEATURES
The LMC8101 is capable of being turned off in order to conserve power. Once in shutdown, the device supply
current is drastically reduced (1µA maximum) and the output will be "Tri-stated".
The shutdown feature of the LMC8101 is designed for flexibility. The threshold level of the SD input can be
referenced to either V^-or V⁺ by setting the level on the SL input. When the SL input is connected to V^-, the SD
threshold level is referenced to V^-and vice versa. This threshold will be about 1.5V from the supply tied to the SL
pin. So, for this example, the device will be in shutdown as long as the SD pin voltage is within 1V of V^-. In order
to ensure that the device would not "chatter" between active and shutdown states, hysteresis is built into the SD
pin transition (see Figure 55 for an illustration of this feature). The shutdown threshold and hysteresis level are
independent of the supply voltage. Figure 55 illustration applies equally well to the case when SL is tied to V⁺
and the horizontal axis is referenced to V⁺ instead. The SD pin should not be set within the voltage range from
1.1V to 1.9V of the selected supply voltage since this is a transition region and the device status will be
undetermined.
Figure 55. Supply Current vs. "SD" Voltage
Table 1 summarizes the status of the device when the SL and SD pins are connected directly to V^-or V⁺:
Table 1. LMC8101 Status Summary
SL
SD
V^−
V^−
V^−
V⁺
V⁺
V⁺
V⁺
V^−
LMC8101 Status
Shutdown
Active
Shutdown
Active
In case shutdown operation is not needed, as can be seen above, the two pins SL and SD can simply be
connected to opposite supply nodes to achieve "Active" operation. The SL and SD should always be tied to a
node; if left unconnected, these high impedance inputs will float to an undetermined state and the device status
will be undetermined as well.
With the device in shutdown, once "Active" operation is initiated, there will be a finite amount of time required
before the device output is settled to its final value. This time is less than 15µs. In addition, there may be some
output spike during this time while the device is transitioning into a fully operational state. Some applications may
be sensitive to this output spike and proper precautions should be taken in order to ensure proper operation at all
times.
TINY PACKAGE
The LMC8101 is available in the DSBGA package as well the 8 pin VSSOP package. The DSBGA package
requires approximately 1/4 the board area of a SOT-23. This package is less than 1mm in height allowing it to be
placed in absolute minimum height clearance areas such as cellular handsets, LCD panels, PCMCIA cards, etc.
More information about the DSBGA package can be found at: http://www.ti.com/packaing.
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