Technical Note
13/15
www.rohm.com
2010.10 - Rev.
© 2010 ROHM Co., Ltd. All rights reserved.
BD3403FV,BD3861FS,BD3883FS
●Notes for use
1) Numbers and data in entries are representative design values and are not guaranteed values of the items.
2) Although ROHM is confident that the example application circuit reflects the best possible recommendations, be sure to
verify circuit characteristics for your particular application. Modification of constants for other externally connected circuits
may cause variations in both static and transient characteristics for external components as well as this Rohm IC. Allow
for sufficient margins when determining circuit constants.
3) Absolute maximum ratings
Use of the IC in excess of absolute maximum ratings, such as the applied voltage or operating temperature range (Topr),
may result in IC damage. Assumptions should not be made regarding the state of the IC (short mode or open mode)
when such damage is suffered. A physical safety measure, such as a fuse, should be implemented when using the IC at
times where the absolute maximum ratings may be exceeded.
4) GND potential
Ensure a minimum GND pin potential in all operating conditions. Make sure that no pins are at a voltage below the GND
at any time, regardless of whether it is a transient signal or not.
5) Thermal design
Perform thermal design, in which there are adequate margins, by taking into account the permissible dissipation (Pd) in
actual states of use.
6) Short circuit between terminals and erroneous mounting
Pay attention to the assembly direction of the ICs. Wrong mounting direction or shorts between terminals, GND, or other
components on the circuits, can damage the IC.
7) Operation in strong electromagnetic field
Using the ICs in a strong electromagnetic field can cause operation malfunction.
8) 2-wire serial control
Because SC and SI terminals are designed for inputting high-frequency digital signals, wiring and layout patterns should
be routed as not to cause interference with the analog-signal-related lines.
9) E Input external resistance (BD3883FS)
To avoid a sudden noise into E Input, external resistance (4.7kΩ) should be connected as close as possible to the IC terminal.
10) Function switching
Action to absorb shock sounds is taken when switching between the Volume, Treble, Middle and Bass functions.
11) Power-ON Reset (BD3883FS)
A built-in circuit for performing initialization inside the IC at Power-ON is provided. Specifically, the initial states are set
as described in the table below. In the case of the setting design, however, to be on the safe side, it is recommended
that data shall be sent to all the addresses as initial data at power-ON and, until this sending operation is completed,
MUTE shall be applied. To avoid malfunctions, serial data signals must be set to the Low state at power-ON/OFF.
Function Initial State
Input Selector MUTE
Input Gain 0 dB
RECOUT OFF
Volume ∞dB
Surround OFF
Treble 0 dB
Middle 0 dB
Bass 0 dB
Rear Volume 0dB
12) Step switching noise (BD3883FS)
For Surround and Rear Volume, an external capacitor C is attached to the CAP pin to control the switching step noise.
In the application circuit, a constant value, as an example, is shown by the CAP pin.
The time constant for charge/discharge of the capacitor C (varying between VBE to 5VBE (2.65V)) controls the slow
switching operation.
The switching time constant T is calculated as the follows:
T=2.55×10
5
×C
VBE has temperature characteristics and may affect the value of the time constant T.
