cxa1998aq Sony Electronics, cxa1998aq Datasheet - Page 23

• Manufacturer Part Number: cxa1998aq
• Description: Recording/playback Equalizer Amplifier
• Manufacturer: Sony Electronics

(2) AMS level setting
The AMS level is set by adjusting HPF gain and cut-off frequency with the external resistor and capacitor at
Pin 9.
G and fc in Fig. 2 are obtained from the following formula.
G = 20log (1 + 100k/R1) [dB]
fc = 1 / (2 ·
Full-wave rectifier is applied for the signal at DET.
Signal detection time is set by the time constant of Pin 11 external resistor and capacitor.
DET signal detection level:
Playback equalizer reference output level of –21dBm is 0dB.
Ex.)
To set AMS level at –25dB, determine and set the constant for Pin 9 external resistor.
(Calculate assuming PBOUT1 = PBOUT2)
First, get the required HPF gain from formula (2).
–7.5dBm = –21dBm + (–25dB) + HPFgain,
so HPF gain = 38.5dB.
Next, get Pin 9 external resistance from formula (1).
38.5dB = 20log (1 + 100k / R1),
so R1
and external resistance is 1.2k .
= –7.5dBm (typ.)
= playback equalizer reference output level + AMS level + HPF gain
1.2k ,
· C1 · R1) [Hz]
(1)
– 23 –
(2)
CXA1998AQ