Power Driver Integrated Full Digital Audio Amplifier
NTP-8230
10. VOLUME & DYNAMIC RANGE CONTROL
Master and channel volumes of the NTP-8230 are independently controlled and softly changed. The
system register address 0x2E is the master volume control that affects 3 channels simultaneously and
the address 0x2F, 0x30 and 0x31 correspond to the channel volume control register for channel 1, 2
and 3 respectively.
The possible Maximum Gain is +48.375dB with using master volume fine control, master volume and
channel volume because the master volume applies the gain to an input signal independent from a
channel volume. However, in such a case, a clipping might occur to prevent a signal overflow error if
the magnitude of the input signal is large enough to exceed 0dB under the combined volume setting.
10.1. Master Volume Control
By setting volume control register (address 0x2E), master volume is controlled from negative infinity
through 24dB with selectable step size as follows. For details on the master volume setting, see the
register value table shown in Appendix C.
Step
0.5 dB
10 dB
Range
+24 ~ -100 dB
-100 ~ -150 dB
Table 5. Level dependent master volume steps
10.2. Channel Volume Control
By setting volume control registers (address 0x2F~0x31), channel volumes are independently
controlled from negative infinity through +24dB with two selectable step sizes as described below, and
in the Appendix C, exact values for channel volume setting are described.
Step
0.5 dB
10 dB
Range
+24 ~ -100 dB
-100 ~ -150 dB
Table 6. Level dependent Channel volume steps
10.3. Master Volume Fine Control
Fine control for master volume is possible (+0.0625dB step up to maximum +0.4375dB boost). Refer
the system register Address 0x2D in the Appendix A.
10.4. Mute and Soft Volume Change
The NTP-8230 enters mute state by setting soft mute flag of register Address 0x26. Soft mute is
implemented so that the volume gradually increases or decreases when mute is turned off or on
respectively. Also the soft mute speed and soft volume change speed rates are programmable.
Designers can minimize the pop noise by controlling the soft mute speed and volume change intervals.
Refer SMH flag of register Address 0x26 and SVI flag of register Address 0x32.
10.5. Auto Mute
The NTP-8230 can mute the sound automatically when the level of input audio signal is lower than the
register-controlled threshold value. The mute can be done by soft mute or PWM switching with 50 %
duty ratio or PWM switching off.
Auto mute is supported for internal channels 1~3 after 2x3 mixer block. Refer register Address 0x33
and 0x34.
Copyright ⓒ NeoFidelity, Inc.
Page 21
Document Number: DS8230 draft ver. 0.1
2011-01-11
ETC [ ETC ]
