AK2400 Datasheet, PDF (38/52 Pages) Asahi Kasei Microsystems – High integrated receiver for PMR-LMR

[AK2400]
Calibration Procedure (Discriminator)
AK2400 employs a function to calibrate free-running frequency of VCO in Discriminator and demodulated
signal level. Before starting RX Operation, calibration is required in order to acquire proper VCO operation
range and demodulated signal level.
Following procedure is required before calibration.
<1> Start up the external TCXO and continuously supply LO signal to AK2400.
<2> Set “110” to 0x0A {BS[2:0]} and start up all circuits. After this operation, the circuits necessary
for calibration (LOBUF, VIREF, Discriminator) will be powered on and calibration can be possible in
500us.
<3> Calibration is begun by setting "1" to address 0x07 {CAL}. When the calibration is executed once, the
calibration operation cannot be stopped excluding master reset. Even if "0" is written in {CAL}, the
calibration is completely executed.
<4> Calibration data is maintained excluding the time when the master reset is executed or DVDD power
supply is down.
<5> It takes 1.5ms for Discriminator to become steady after the calibration is completed.
LOIN（external） ^Unstable
{BS[1:0]}
“01”
LOBUF
VIREF
Discriminator
{CAL}
Internal
Discriminator
(500us)
Unstable
“11”
(1.3ms)
Stable
Unstable
Reset itself automatically after calibration is completed
(1.5ms)
Figure 16 Power-up sequence recommendation
014008989-E-01
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