AK2364 Datasheet, PDF (19/26 Pages) Asahi Kasei Microsystems – Two-way Radio Filterless FM Detector LSI

[AK2364]
14. Calibration Procedure
1) AVDD=2.6 to 3.6V operation
When you use AK2364 in AVDD=2.6 to 3.6V operation, VREFA pin is connected to AVDD pin for
power supplying. Please set LDO (Low Drop Out) power off setting. Refer to 4-1) in page 22.
AK2364 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 in LDO power off setting.
<1> Start up the external TCXO and continuously supply LO signal to AK2364.
<2> Set “11” to 0x01 {BS[1:0]} and start up all circuits. After this operation, the circuits necessary
for calibration (LOBUF, VIREF and Discriminator) will be powered on and calibration can be
possible in 500us.
<3> Calibration is begun by setting "1" to address 0x02 {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.
Power-up sequence recommendation
LOIN（external） ^Unstable
{BS[1:0]}
LOBUF
VIREF
Discriminator
{CAL}
Internal
Discriminator
“01”
(500μs)
Unstable
“11”
(1.3ms)
Stable
Unstable
Reset itself automatically after calibration is completed
(1.5ms)
MS1431-E-01
- 19 -
2012/10