TS615IPWT datasheet(26/36 Pages) STMICROELECTRONICS

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TS615

Power Supply Bypassing

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8 Power Supply Bypassing

Correct power supply bypassing is very important for optimizing performance in high-frequency ranges.

Bypass capacitors should be placed as close as possible to the IC pins to improve high-frequency

bypassing. A capacitor greater than 1

µF is necessary to minimize the distortion. For a better quality

bypassing, a capacitor of 10nF is added using the same implementation conditions. Bypass capacitors

must be incorporated for both the negative and the positive supply.

8.1 Single power supply

The TS615 can operate with power supplies ranging from 12V to 5V. The power supply can either be

single (12V or 5V referenced to ground), or dual (such as ±6V and ±2.5V).

In the event that a single supply system is used, new biasing is necessary to assume a positive output

dynamic range between 0V and +VCC supply rails. Considering the values of VOH and VOL, the amplifier

will provide an output dynamic from +0.5V to 10.6V on 25

Ω load for a 12V supply and from 0.45V to 3.8V

on 10

Ω load for a 5V supply.

The amplifier must be biased with a mid-supply (nominally +VCC/2), in order to maintain the DC

component of the signal at this value. Several options are possible to provide this bias supply, such as a

virtual ground using an operational amplifier or a two-resistance divider (which is the cheapest solution).

A high resistance value is required to limit the current consumption. On the other hand, the current must

be high enough to bias the non-inverting input of the amplifier. If we consider this bias current (30

µA

max.) as the 1% of the current through the resistance divider to keep a stable mid-supply, two resistances

of 2.2k

Ω can be used in the case of a 12V power supply and two resistances of 820Ω can be used in the

case of a 5V power supply.

The input provides a high-pass filter with a break frequency below 10Hz which is necessary to remove the

original 0 volt DC component of the input signal, and to fix it at +VCC/2.

Figure 63. Circuit for power supply bypassing

-VCC

+VCC

µF

10nF

TS615

µF

10nF

-VCC

+VCC

µF

10nF

TS615

µF

10nF

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