THS4524MDBTREP datasheet(35/48 Pages) NSC

35 / 48 page

Frequency (Hz)

-80

-82

-84

-86

-88

-90

-92

-94

-96

-98

-100

100

1 k

10 k 20 k

THS4524 and PCM3168 THD+N vs FREQUENCY

(No Weighting)

Frequency (Hz)

-95

-97

-99

-101

-103

-105

-107

-109

-111

-113

-115

100

1 k

10 k 20 k

G = 5

G = 1

G = 2

THS4524 and PCM4204 THD+N

vs FREQUENCY (No Weighting, at Higher Gains)

THS4524-EP

www.ti.com

SBOS609A – JUNE 2012 – REVISED AUGUST 2013

Figure 80 shows the THS4524 and PCM4204 THD+N

EVM is configured for both differential inputs as

versus frequency with no weighting at higher gains.

shown in Figure 61 and for single-ended input as

shown in Figure 62 with 1-k

Ω resistors for RF and RG,

and 24.9-

Ω resistors in series with each output to

isolate the outputs from the reactive load of the

coaxial cables. To limit the noise from the external

EVM and cables, a 2.7-nF capacitor is placed

differentially across the PCM3168A inputs. The

THS4524 is operated with a single-supply +5-V

supply so the output common-mode of the THS4524

defaults to +2.5 V as required at the input of the

PCM3168A. The PCM3168A EVM is configured and

operated as described in the PCM3168AEVM User

Guide. The ADC was tested with an external

THS4524 EVM with both single-ended input and

differential inputs. In both configurations, the results

are the same. Figure 81 shows the THD+N versus

frequency and Table 5 compares the result to the

PCM3168 data sheet typical specification at 1 kHz.

Both graphs show that it makes an excellent drive

amplifier for this ADC. Note: a 2700 series Audio

Figure 80. THS4524 and PCM4204: THD+N versus

Analyzer from Audio Precision is used to generate

Frequency with No Weighting at Higher Gains

the input signals to the THS4524 and to analyze the

digital data from the PCM3168.

Audio ADC Driver Performance:

THS4524 and PCM3168 Combined

Performance

The THS4524 is also tested as the drive amplifier for

the PCM3168A ADC input. The PCM3168A is a high-

performance, single-chip, 24-bit, 6-in/8-out, audio

coder/decoder

(codec)

with

single-ended

and

differential selectable analog inputs and differential

outputs. The six-channel, 24-bit ADC employs a

ΔΣ

modulator and supports 8-kHz to 96-kHz sampling

rates and a 16-bit/24-bit width digital audio output

word on the audio interface. The eight-channel, 24-bit

digital-to-analog converter (DAC) employs a

ΔΣ

modulator and supports 8-kHz to 192-kHz sampling

rates and a 16-bit/24-bit width digital audio input word

on the audio interface. Each audio interface supports

I2S™, left-/right-justified, and DSP formats with 16-

bit/24-bit word width. In addition, the PCM3168A

Figure 81. THS4524 and PCM3168: THD+N versus

supports the time-division-multiplexed (TDM) format..

Frequency with No Weighting

The PCM3168A provides flexible serial port interface

and many other advanced features. Refer to the

PCM3168A product data sheet for more information.

Table 5. 1-kHz AC Analysis: Test Circuit vs

PCM3168 Data Sheet Typical Specifications

The PCM3168A EVM is used to test the audio

(fS = 48 kSPS)

performance of the THS4524 as a drive amplifier.

The standard PCM3168A EVM is provided with

Configuration

Tone

THD+N

OPA2134 op amps that are used to convert single-

THS4524 and

1 kHz

–92.6 dBc

ended inputs to differential to drive the ADC. For

PCM3168

testing, the op amp output series resistors are

PCM3168 Data

1 kHz

–93 dBc

removed from one of the channels and a THS4524,

sheet (typ)

mounted on its standard EVM, is connected to the

ADC inputs via short coaxial cables. The THS4524

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THS4524MDBTREP Datasheet(PDF) 35 Page - National Semiconductor (TI)

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