audio DAC PCM1502 output level

emmanuel63

Well-known member
Hello,

I use a a pcm1502 audio doc. It works very well but the line output level is very high.
With a full scale sine at 1 kHz, I get a 6V peak to peak output level.
Is it normal ?

My setup :
Teensy 4.0


VCC = Vin
3.3v = N.C.
GND = GND
FLT = GND
DMP = GND
SCL = GND
BCK = BCLK1 (21)
DIN = OUT1A (7)
LCK = LCRLK (20)
FMT = GND
XMT = 3.3V (HIGH)

my test code (I use the 2nd IS2 bus)
Code:
#include <Audio.h>
#include <Wire.h>
#include <SPI.h>
#include <SD.h>
#include <SerialFlash.h>

// GUItool: begin automatically generated code
AudioSynthWaveformModulated waveformMod1;   //xy=453.5,358
AudioOutputI2S2           i2s2_1;           //xy=752.5000076293945,358.7500047683716
AudioConnection          patchCord1(waveformMod1, 0, i2s2_1, 0);
AudioConnection          patchCord2(waveformMod1, 0, i2s2_1, 1);
// GUItool: end automatically generated code


void setup() {
  AudioMemory(15);   
  delay(100);                           
  waveformMod1.begin(1, 1000, WAVEFORM_SINE);
}

void loop() {

}
 
Is it normal ?

Yes, it is. PCM5102A board, powered with 5Vdc, connected to a Teensy 3.2. The PCM5102A chip has a charge pump internally to realize an output voltage of 2.1Vrms.


SDS00067.png

Paul
 
Last edited:
Ok, from the datasheet the max output is 2.1V rms, which is about 3V which will be 6V peak to peak. Yes, it's normal.
 
Last edited:
This board has 3pcs 5V-to-3V3 regulators on it. The AVDD, CPVDD and DVDD pins of the chip have their own supply.

pcm5102board.png

Paul
 
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