LC89052T Datasheet, PDF (12/42 Pages) Sanyo Semicon Device – Digital Audio Interface Receiver

LC89052T
8.3.2 Oscillator amplifier (XIN and XOUT)
• The following methods can be used to supply the clock signal to the internal oscillator amplifier.
XIN
XIN
CKOUT
CKOUT
XOUT
(a) Oscillator element
XIN
CKOUT
XOUT
(c) CKOUT clock signal
XOUT
(b) External clock signal
Figure 8.3 XIN and XOUT Pin Circuit Configurations
• When you connect an oscillator, use the one with the fundamental frequency. Since the load capacitance depends on
the oscillator characteristics, give careful consideration.
• Since the clock supplied to the XIN pin is normally used for the following purposes, the clock signal should be
present all the time.
—Externally supplied clock used when the PLL circuit is unlocked and when XIN is the clock source
—For calculation of sampling frequencies of the input data
• Input a clock with a frequency of 11.2896M, 12.288M, 16.9344M, 22.5792M, 24.576M, or 33.8688MHz according to
the setting of the XISEL[2:0]. Input digital data only after the XISEL[2:0] has been set to match the set frequency and
the oscillator or external clock input frequency. The LC89052T may malfunction if data is input when the input
frequency and the set frequency are not consistent.
• The LC89052T operates even when the frequency set with the XISEL[2:0] and the frequency supplied to the XIN pin
are different. However, continuity at clock switching time and correct input fs calculation are not guaranteed.
• The LC89052T supports a structure in which CKOUT pin is connected to the XIN pin to set XISEL3, requiring no
oscillator. However, since only VCO can be used as the source clock, the VCO free-running frequency (10M to
16MHz) is output from the CKOUT pin when the PLL is not locked. Furthermore, input fs calculation and limitation
are impossible with this approach. Also, since no clock is supplied to the oscillator amplifier circuit when the VCO is
set to stop, the whole system stops. This function is available only for the PLLCK[1:0] = "00" setting, which is 256fs.
Other system clock settings might cause malfunction.
• Normally the oscillator amplifier stops automatically when the PLL is locked. It is possible to change to a continuous
operation mode with AMPCNT. Setting the LC89052T to the continuous operation mode makes it possible to
calculate the input sampling frequency even when the PLL is locked. However, since both the oscillator amplifier
clock and the PLL clock signals coexist in that case the user must pay attention and make sure audio quality is not
adversely affected.
• The oscillator amplifier can be stopped when not required by setting the AMPOPR. However, the application must
maintain its state for at least 10ms until the oscillator stabilizes, when returning from stop to operation mode. After
that the LC89052T must be returned to the normal operation mode.
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