BD37524FS_1003 Datasheet, PDF (19/26 Pages) Rohm – Sound Processor with Built-in 3-band Equalizer

BD37524FS
Technical Note
About Level meter
（１） The operation of circuit
Level meter is a function which gives DC voltage proportional to the size of signal of sound. It detects
the peak level of signal and keeps the peak level, so that it is possible to monitor the size of signal by
resetting DC voltage kept with suitable interval.
（２） The way to reset level meter output
Please send reset data through I²C BUS
When reset output of level meter：Send D6 = “ 1 “ of select address 02(hex).
When cancel of output reset of level meter (HOLD)… → Send D6 = “ 0 “ of select address 02(hex).
（３） The settings about period of reset
Peak hold operation will start after HOLD data is transmitted. Set the WAIT time after HOLD data
according to the frequency bandwidth detected.
WAIT time must be set to a minimum of one cycle over the detected frequency bandwidth.
Ex) Detected frequency bandwidth is above 40Hz, 『40Hz = 25ms = WAIT time』
transmission
Transmission Example by I²C BUS
I²CBUS
(RESET)
(HOLD)
80 ¹ 02 40 80 02 00
0
LOUT [ V ]
RESET
START
HOLD
START
Wait time
(25msec)
※fin＝40Hz
detect
t
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19/25
2010.03 - Rev.A