BU8241FSE2 [ROHM]
TELECOM, CORDLESS, SUPPORT CIRCUIT, PDSO24, SSOP-24;
| 型号： | BU8241FSE2 |
| 厂家： | 
ROHM |
| 描述： | TELECOM, CORDLESS, SUPPORT CIRCUIT, PDSO24, SSOP-24 无绳技术 电信 光电二极管 电信集成电路 |
| 文件： | 总12页 (文件大小：225K) |
| 中文： | 中文翻译 | 下载： | 下载PDF数据表文档文件 |
Communication ICs
Cross point mixer for telephones
BU8241F / BU8241FS / BU8242F / BU8244F
The BU8241F, BU8241FS, BU8242F, and BU8244F are ICs developed for use with cordless telephones, and are
equipped with switching and mixing functions. In addition, these ICs are provided with an internal power save function
which enables the circuit to be run on line current if the power supply fails, by connecting a switch between the circuit
and a new handset, reducing line current consumption. A series of these ICs is also under development, based on the
number of circuits.
FApplications
Telephones, telephone answering machines, cordless
telephones
FFeatures
1) Eight input signals are selected and mixed by a
cross-point, and output to eight pins (BU8241F/
BU8241FS).
3) Serial binary data input.
4) Low voltage and current consumption.
2) A power save mode enables the circuit to run on line
current if the power supply fails.
1. Line current consumption reduced
(IDD2 = 580µA)
2. IN1 ! OUT1 and IN2 ! OUT2 only are on
266
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FBlock diagram
267
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FAbsolute maximum ratings (Ta = 25_C)
FRecommended operating range (Ta = 25_C)
268
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FElectrical characteristics (unless otherwise noted, Ta = 25_C, VDD = 5V)
269
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FPin descriptions
FInput/output circuits
270
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FCircuit operation
Sections (1) to (3) below describe operation using the
BU8241F and BU8241FS as examples.
(1) Analog signals pass through an input amplifier and
are supplied to eight switches.
After the 64 data bits have been read, supply of the rising
edge of the clock is stopped, the LATCH pin is set to
HIGH, and the switches are set. (See Figure 2 for the tim-
ing waveform.)
The analog input signals are turned on and off by the
switches and can thus be directed to any desired output
amplifier. Using mixing resistors connected to the out-
puts of the switches, and feedback resistors, each output
amplifier can output a signal that is a mix of up to eight
input signals.
To change a switch setting, new setting data and shift
clocks must be supplied for 64 bits of data, and the
LATCH pin set to HIGH. If the LATCH pin is set to HIGH
before 64 shift clocks have been supplied, or after more
than 64 have been supplied, the switches cannot be set
properly. (See Table 1 for the logic of switch settings.)
Table.1 Switch Sn stage (Note 6)
(2) The switch states are set using a 64-bit shift register
and data latch.
The shift register reads the data at the rising edge of the
shift clock, and stores it until the next data is read at the
rising edge of the next shift clock.
(3) The power save mode is set as long as the PS pin is
kept HIGH. (See Table2forthepowersavesettinglogic.)
In the power save mode, the following are fixed : IN1 !
OUT1 (S1 = ON) and IN2 ! OUT2 (S10 = ON). (The oth-
er 62 switches are off.) In addition, the line current is re-
duced. When the PS pin goes from HIGH to LOW, the IC
state switches from the power save mode back to normal
operation. At that point, the state of the switch remains
in the power save mode (only S1 and S10 are on). (See
Figure 3 for the timing waveform in the power save
mode.)
(5) With the BU8244F, DIN is 16 bits.
The ON path in the power save mode is the same for the
BU8241F and BU8241FS, but the pertinent switches are
S1 and S6.
Table.2 Power save setting theory
(4) With the BU8242F, of the 64 data bits, the following
should be input at LOW level : D3, D4, D11, D12, D17 to D32,
D35, D36, D43, D44, D51, D52, D59, and D60.
271
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FApplication example
272
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FSelecting attached components
1) Components related to power supply and bias
3) Components related to output pins
C602: VDD bias capacitor; normally 10µF
C613 to C620: DC cutoff capacitor. A value should be
selectedwhich does not attenuate voice
signals in the high band (300 Hz X).
R613 to R620: Output load resistors. This should nor-
mally be left open.
C603: VB decoupling capacitor; normally 10µF
2) Components related to input pins
If using R615 to R620, select values that
result in a total input impedance of 10kΩ
or greater on the output side. If the total
impedance is less than 10kΩ, the load
on the output amplifier of the cross-point
mixer will be excessive, and signals
may be lost.
C605 to C612: DC cutoff capacitor. A value should be
selectedwhich does not attenuate voice
signals in the high band (300 Hz X).
R605 to R612: Resistor which sets the input level. This
should normally be left open.
The constants shown in Figure 8 are set
to match the oscillator output imped-
ance.
273
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FOperation notes
(1) Turning on the power supply
(4) Gain and noise when mixing signals
When the power supply is turned on, the shift register is
in an indeterminate state. After turning on the power sup-
ply, switch settings should be entered by supplying shift
clock pulses to shift 64 bits of data into the shift register,
and then setting the LATCH pin to HIGH. (For the
BU8244, send 16 clock pulses.)
Increasing the number of signals mixed in a single output
(increasing the number of switches connected to the
same output amplifier that are on) causes a slight drop
in gain. With the BU8241 and BU8241FS /
BU8242F, increasing the number of signals mixed in a
single output (increasing the number of switches con-
nected to the same output amplifier that are on) causes
a slight increase in the noise level in terms of logic. If
noise is a problem, we recommend limiting the number
of signals mixed in a single output.
(2) Setting serial data
If the number of bits shifted or clock pulses applied is less
than or more than the number stated above, the switches
will not be set properly. Never apply shift clock pulses
when the LATCH pin is HIGH. Doing so will change the
data latch contents.
(5) Output load capacitance
The capacitance connected to GND in relation to an out-
put pin (the output load capacitance) should be kept to
50pF or lower. (BU8241F/BU8241FS/ BU8242F)
(3) Drive impedance
The input impedance Zin is 80 ± 32kΩ.
To suppress input gain and loss, we recommend using
the drive impedance shown in the table below.
If the level is to be attenuated at the input pin, make sure
the level is not affected by the internal resistance of the
IC, as shown in Figure 10. This can cause gain and/or
loss.
FElectrical characteristic curves
274
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FElectrical characteristic curves
275
Communication ICs
BU8241F / BU8241FS / BU8242F / BU8244F
FExternal dimensions (Units: mm)
276
Appendix
Notes
No technical content pages of this document may be reproduced in any form or transmitted by any
means without prior permission of ROHM CO.,LTD.
The contents described herein are subject to change without notice. The specifications for the
product described in this document are for reference only. Upon actual use, therefore, please request
that specifications to be separately delivered.
Application circuit diagrams and circuit constants contained herein are shown as examples of standard
use and operation. Please pay careful attention to the peripheral conditions when designing circuits
and deciding upon circuit constants in the set.
Any data, including, but not limited to application circuit diagrams information, described herein
are intended only as illustrations of such devices and not as the specifications for such devices. ROHM
CO.,LTD. disclaims any warranty that any use of such devices shall be free from infringement of any
third party's intellectual property rights or other proprietary rights, and further, assumes no liability of
whatsoever nature in the event of any such infringement, or arising from or connected with or related
to the use of such devices.
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otherwise dispose of the same, no express or implied right or license to practice or commercially
exploit any intellectual property rights or other proprietary rights owned or controlled by
ROHM CO., LTD. is granted to any such buyer.
Products listed in this document use silicon as a basic material.
Products listed in this document are no antiradiation design.
The products listed in this document are designed to be used with ordinary electronic equipment or devices
(such as audio visual equipment, office-automation equipment, communications devices, electrical
appliances and electronic toys).
Should you intend to use these products with equipment or devices which require an extremely high level of
reliability and the malfunction of with would directly endanger human life (such as medical instruments,
transportation equipment, aerospace machinery, nuclear-reactor controllers, fuel controllers and other
safety devices), please be sure to consult with our sales representative in advance.
About Export Control Order in Japan
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Order in Japan.
In case of export from Japan, please confirm if it applies to "objective" criteria or an "informed" (by MITI clause)
on the basis of "catch all controls for Non-Proliferation of Weapons of Mass Destruction.
Appendix1-Rev1.0
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