µ
PD9930
Table 2-3 Digital Gain Control Functions
Voice Send Signal Gain Control Voice Receive Signal Gain Control
Gain setting method
Gain setting range
Microcontroller command
0 to –2.8 dB (0.4 dB steps)
Microcontroller command
0 to –2.4 dB (0.8 dB steps)
Tone Gain Control
Microcontroller command
0 to –30 dB (1 dB steps), –38.5 dB
2.1.6 Power Up/Down Control
The
µ
PD9930 includes a power down function for reducing power consumption. Power down control is by
the two methods described below.
(1) Input/output amplifier power up/down control
Power up/down for both the input and output amplifiers can be controlled.
When the power down function is used for all input amplifiers, both pre-filter and A/D enter the power down state.
When the power down function is used for the accessory output amplifier and the receiver 1 amplifier, the D/A
also enters power down state.
(2) Stand-by mode
Low power consumption can be realized in the mode in which all chip operation is stopped. The stand-by mode
is set by power down command. Operation restarts by power up command.
The following control registers are used to enable the control described above.
Control Method
Power up/down control of input/output amplifier
(not including receiver amplifier 2)
Power up/down control of receiver amplifier 2
Set/clear of standby mode
Registers Used
Input/output amplifier control register (AMPCR)
Send analog gain/receiver amplifier 2 control register (TXGCR)
Power up control command (PUPCMD)
Power down control command (PDWCMD)
An outline diagram of power down control is shown in
Figure 2-5.
12
NEC [ NEC ]
