YDA135 Datasheet, PDF (8/22 Pages) YAMAHA CORPORATION – STEREO 5W-20W DIGITAL AUDIO POWER AMPLIFIER CONTROLLER

Description of functions
Amplifier functions
NFINL/
NFINR
YDA135
YDA135
CD
RD
CDIL/
CDIR
CDOL/
CDOR
PVDD
NFPL/ ^RS
NFPR
RFB
SENSEPL/
SENSEPR
RI
INL/
INR
VREFL/
VREFR
CREF
Balanced
RNP
Pulse Width
Modulation
Unit
RNP
(L channel/
R channel)
HP_L/
HP_R
HN_L/
HN_R
LP_L/
LP_R
LN_L/
LN_R
LO
CO
CO
RL
LO
First stage
operational
amplifier
section
Digital
amplifier
section
Amplifier functions block diagram
SENSENL/
SENSENR
NFNL/
NFNR
RS
PVSS
The amplifier section of this IC consists of the first stage operational amplifier and the second digital amplifier.
The gain of the first stage operational amplifier is set with externally connecting an input resistor (RI) and feedback
resistor (RFB). The second stage digital amplifier connects Power MOSFET externally, of which output is fed back to
the modulation circuitry of the digital amplifier section through the external feedback resistors (RNFH and RNFL).
This feature realizes the low distortion rate.
To prevent occurrence of penetration current caused by simultaneous on state of external Power MOSFET, a period
in which both PMOS and NMOS are not on state ("off time") is provided. This time is set by using an external
resistor (RD) and capacitor (CD).
The output of Power MOSFET is connected to the speakers through the secondary low pass filter consisting of an
inductor (Lo) and a capacitor (Co). This feature removes the carrier frequency component contained in the output of
Power MOSFET, and sent only audio signals to the speakers.
Gain setting
The gain of first stage operational amplifier is calculated by the following formula. The gain of the digital amplifier
section that includes the gain (8dB) of internal digital amplifier section and gain of the external feedback resistor is
calculated by the following formula.
Gain
First stage operational amplifier section _{20*log(2*RFB/RI) dB (Gain is set by RI and RFB. Condition : RI > 2kΩ)}
Digital amplifier section
8+20*log(1+RNFH/RNFL) dB
8