BA3826 Rohm, BA3826 Datasheet - Page 4

• Manufacturer Part Number: BA3826
• Description: Band-pass filter for spectrum analyzer
• Manufacturer: Rohm

(2)
This circuit extracts the required frequency range from
the input signal and amplifies it.
The center frequency is determined by the value of the
current flowing through the resistor connected to pin 14.
Q is set to 3.5 (Typ.).
Due to the characteristics of the band-pass filter circuit,
the circuit has a transition rise and fall characteristic. Due
to the transition rise characteristic, five input cycles are
required until peak output is reached.
When RESET is input, a built-in circuit cancels the fall
transition characteristic (input the reset signal for 0.5ms).
(3)
The DET circuit detects the signal selected by the band
pass filter and performs peak hold.
The RESET Driver discharges the charge stored in the
capacitor. After the RESET input is released, the RESET
Driver discharges continuously for 14ms.
Audio ICs
Band-pass filter circuit
DET circuit
(4)
1) RESET timing
The RESET input is used as the RESET signal for the
band-pass filter circuit and the DET circuit. The setting
time is 0.5ms min.
When performing a RESET input, disable both the Lin
and Rin inputs. The synchronous shift in this case must
be "0.1ms max.
2) Output select timing
The audio input signal is not accepted when the RESET
input and L (R) inputs are low. There are no particular re-
strictions on the select input for the various frequencies,
but there are delay times until the peak voltage is settles
(see (a) and (b) below). Accordingly, set the read timing
for the DET signal after the longer of the delay times in
(a) and (b).
(a)
5 cycles is required due to the transition rise characteris-
tic.
Timing
For the band-pass filter, a sampling time of at least
BA3826S
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