ADAV802_15 datasheet(14/53 Pages) AD

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ADAV802

Preliminary Technical Data

Rev. Pr G | Page 14 of 53

Recovery and Normal Recovery Modes. If the output level of

the ADC exceeds the Attack Threshold then Attack Mode is

initiated. When Attack Mode has reduced the PGA gain to

suitable levels the ALC will attempt to recovery the gain to its

original level. If the ADC output level exceeds the level set by

the Recovery Threshold bits a counter is incremented

(GAINCNTR). This counter is incremented, at intervals equal

to the Recovery Time selection, if the ADC has any excursion

above the Recovery Threshold. If the counter reaches its

maximum value, determined by the GAINCNTR bits in ALC

Control Register 1, the PGA gain is deemed suitable and no

further gain recovery is attempted. If, at any time, the ADC

output level exceeds the Attack Threshold, Attack Mode is

reinitiated and the counter is reset

WAIT FOR SAMPLE

IS SAMPLE

GREATER THAN ATTACK

THRESHOLD?

DECREASE GAIN BY 0.5dB

AND WAIT ATTACK TIME

YES

IS A RECOVERY

MODE ENABLED?

YES

NORMAL RECOVERY

IS SAMPLE

BELOW RECOVERY

THRESHOLD?

WAIT FOR SAMPLE

WAIT

RECOVERY

TIME

INCREASE GAIN BY 0.5dB

WAIT RECOVERY TIME

HAS GAIN BEEN

FULLY RESTORED?

YES

IS SAMPLE

BELOW RECOVERY

THRESHOLD?

WAIT FOR SAMPLE

WAIT

RECOVERY

TIME

INCREASE GAIN BY 0.5dB

WAIT RECOVERY TIME

HAS GAIN BEEN

FULLY RESTORED?

YES

INCREMENT

GAINCNTR

IS GAINCNTR

AT MAXIMUM?

YES

LIMITED RECOVERY

IS SAMPLE

ABOVE ATTACK

THRESHOLD?

IS SAMPLE

ABOVE ATTACK

THRESHOLD?

ATTACK MODE

Figure 6. ALC Flow Diagram

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