THS4541 Datasheet, PDF (49/62 Pages) Texas Instruments – Fully Differential Amplifier

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THS4541
SLOS375 – AUGUST 2014
11 Power-Supply Recommendations
The THS4541 is principally intended to operate with a nominal single-supply voltage of +3 V to +5 V. Supply-
voltage tolerances are supported with the specified operating range of 2.7 V (10% low on a 3-V nominal supply)
and 5.4 V (8% high on a 5-V nominal supply). Supply decoupling is required, as described in the Terminology
and Application Assumptions section. Split (or bipolar) supplies can be used with the THS4541, as long as the
total value across the device remains less than 5.5 V (absolute maximum). The thermal pad on the RGT
package is electrically isolated; connect the thermal pad to any potential plane for heat spreading.
Using a negative supply to deliver a true swing to ground output in driving SAR ADCs may be desired. While the
THS4541 quotes a rail-to-rail output, linear operation requires approximately a 200-mV headroom to the supply
rails. One easy option for extending the linear output swing to ground is to provide the small negative supply
voltage required using the LM7705 fixed –230-mV, negative-supply generator. This low-cost, fixed negative-
supply generator accepts the 3-V to 5-V positive supply input used by the THS4541 and provides a –230-mV
supply for the negative rail. Using the LM7705 provides an effective solution, as shown in the TI Designs
TIDU187, Extending Rail-to-Rail Output Range for Fully Differential Amplifiers to Include True Zero Volts.
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