TSH310 Power Supply Considerations
10/19
4 Power Supply Considerations
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 1µF is necessary to minimize the distortion. For better quality
bypassing, a capacitor of 10nF can be added using the same implementation conditions. Bypass
capacitors must be incorporated for both the negative and the positive supply.
For example: on the SO8_SINGLE_HF board, these capacitors are C6, C7, C8, C9.
Single power supply
In the event that a single supply system is used, new biasing is necessary to assume a positive output
dynamic range between 0V and +V
CC
supply rails. Considering the values of VOH and VOL, the amplifier
will provide an output dynamic from +0.9V to +4.1V on 1kΩ load.
The amplifier must be biased with a mid-supply (nominally +V
CC
/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 (55µA
max.) as the 1% of the current through the resistance divider to keep a stable mid-supply, two resistances
of 470Ω can be used.
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 +V
CC
/2.
Figure 27 illustrates a 5V single power supply configuration for the SO8_SINGLE evaluation board (see
Evaluation Boards on page 9).
Figure 26: Circuit for power supply bypassing
+
-VCC
+VCC
10microF
+
10nF
10microF
+
10nF
-
+
-VCC
+VCC
10microF
+
10nF
10microF
+
10nF
-
Obsolete Product(s) - Obsolete Product(s)
