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IRAUDAMP10 REV
1.1
IRAUDAMP10 Overview
The IRAUDAMP10 features a 2CH self-oscillating type PWM modulator for the smallest space,
highest performance and robust design. This topology represents an analog version of a second-
order sigma-delta modulation having a Class D switching stage inside the loop. The benefit of the
sigma-delta modulation, in comparison to the carrier-signal based modulation, is that all the error
in the audible frequency range is shifted to the inaudible upper-frequency range by nature of its
operation. Also, sigma-delta modulation allows a designer to apply a sufficient amount of error
correction.
The IRAUDAMP10 self-oscillating topology consists of following essential functional blocks.
Front-end
integrator
PWM
comparator
Level
shifters
Gate drivers and MOSFETs
Output
LPF
Integrator
Referring to Fig 16 below, the input operational amplifier of the IRS2052M forms a front-end
second-order integrator with R3x, C2x, C3x, and R2x. The integrator that receives a rectangular
feedback signal from the PWM output via R4x and audio input signal via R3x generates a
quadratic carrier signal at the COMP pin. The analog input signal shifts the average value of the
quadratic waveform such that the duty cycle varies according to the instantaneous voltage of the
analog input signal.
PWM Comparator
The carrier signal at the COMP pin is converted to a PWM signal by an internal comparator that
has a threshold at middle point between VAA and VSS. The comparator has no hysteresis in its
input threshold.
Level Shifters
The internal input level-shifter transfers the PWM signal down to the low-side gate driver section.
The gate driver section has another level-shifter that level shifts up the high-side gate signal to the
high-side gate driver section.
