THS4524MDBTEP datasheet(33/48 Pages) NSC

33 / 48 page

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THS4524 and PCM4204

1-kHz FFT

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THS4524 and PCM4204 THD+N

vs FREQUENCY (No Weighting)

THS4524-EP

www.ti.com

SBOS609A – JUNE 2012 – REVISED AUGUST 2013

Audio ADC Driver Performance:

+15 V, +5 VA and +5 VD, to a +5-V external power

THS4524 and PCM4204 Combined

supply (EXT +3.3 was not used) and connecting –15

Performance

V and all ground inputs to ground on the external

power supply. Note only one external +5-V supply

To show achievable performance with a high-

was needed to power all devices on the EVM.

performance audio ADC, the THS4524 is tested as

the drive amplifier for the PCM4204. The PCM4204 is

A SYS-2722 Audio Analyzer from Audio Precision

a high-performance, four-channel ADC designed for

(AP) provides an analog audio input to the EVM; the

professional and broadcast audio applications. The

PCM-formatted digital output is read by the digital

PCM4204 architecture uses a 1-bit delta-sigma (

ΔΣ)

input on the AP.

modulator per channel that incorporates an advanced

Data were taken using a 256-fS system clock to

dither scheme for improved dynamic performance,

achieve fS = 48-kHz measurements, and audio output

and supports PCM output data. The PCM4204

uses PCM format. Other data rates and formats are

provides a flexible serial port interface and many

expected to show similar performance in line with that

other advanced features. Refer to the PCM4204

shown in the product data sheet.

product data sheet for more information.

Figure 77 shows the THD+N vs Frequency response

The PCM4204EVM can test the audio performance of

with no weighting; Figure 78 shows an FFT of the

the THS4524 as a drive amplifier. The standard

output with 1-kHz input tone. Input signals to the

PCM4204EVM is provided with four OPA1632 fully-

PCM4204 for these tests is 0.5 dBFS. Dynamic range

differential amplifiers, which use the same device

is also tested at –60 dBFS, fIN = 1 kHz, and A-

pinout as the THS4524. For testing, one of these

weighted. Table 4 summarizes testing results using

amplifiers is replaced with a THS4524 device in same

the THS4524 together with the PCM4204 versus

package (MSOP), and the power supply changes to a

typical data sheet performance measurements, and

single-supply +5V. Figure 79 shows the modifications

show that it make an excellent drive amplifier for this

made to the circuit. Note the resistor connecting the

ADC.

VOCM input of the THS4524 to the input common-

mode drive from the PCM4204 is shown removed

The test circuit shown in Figure 79 has a gain = 0.27

and is optional; no performance change was noted

and attenuates the input signal. For applications that

with it connected or removed. The THS4524 is

require higher gain, the circuit was modified to gains

operated with a +5-V single-supply so the output

of G = 1, G = 2, and G = 5 by replacing the feedback

common-mode defaults to +2.5 V as required at the

resistors (R33 and R34) and re-tested to show

input of the PCM4204. The EVM power connections

performance.

were modified by connecting positive supply inputs,

Figure 77. THS4524 and PCM4204: THD+N versus

Figure 78. THS4524 and PCM4204 1-kHz FFT

Frequency with No Weighting

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