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参数资料
| 型号： | MAX4548 |
| 厂商： | Maxim Integrated Products, Inc. |
| 元件分类： | 数字信号处理 |
| 英文描述： | Fixed-Point Digital Signal Processors 240-BGA MICROSTAR |
| 中文描述： | 串行控制、三组3x2音频/视频交叉点开关 |
| 文件页数： | 16/20页 |
| 文件大小： | 273K |
| 代理商： | MAX4548 |
M
Slave Address (Address Byte)
The MAX4548 uses an 8-bit slave address. To select a
slave address, connect A0 and A1 to V+ or GND. The
MAX4548 has four possible slave addresses, thus a
maximum of four of these devices may share the same
2-bit address bus. The slave devices on the MAX4548
monitor the serial bus continuously, waiting for a start
condition followed by an address byte. When a slave
device recognizes its address, it acknowledges that it is
ready for further communication by pulling the SDA line
low for one clock period.
3-Wire S erial Interfac e
The MAX4549 3-wire serial interface is SPI/QSPI/
MICROWIRE-compatible. An active-low chip-select (
CS
)
input enables the device to receive data for the serial
input (DIN). Data is clocked in on the rising edge of the
serial-clock (SCLK) signal. A total of 24 bits is needed in
each write cycle. Segmented write cycles are allowed
(three 8-bit-wide transfers) if
CS
remains low. The first
bit clock into the MAX4549 is the command byte’s MSB,
and the last bit clocked in is the data byte’s LSB. When
programming the COM_ _ registers and the Clickless
Mode register, the last eight bits of the data word are
“don’t care.” While shifting data, the device remains in
its original configuration. After all 24 bits are clocked
into the input shift register, a rising edge on
CS
latches
the data into the MAX4549 internal registers, initiating
the device’s change of state. Figures 6 and 7 and Table
7 show the details of the 3-wire protocol, as it applies to
the MAX4549.
DOUT is the shift register’s output. Data at DOUT is sim-
ply the input data delayed by 24 clock cycles, with data
appearing synchronous with SCLK’s falling edge.
Transitions at DIN and SCLK have no effect when
CS
is
high, and DOUT holds the last bit in the shift register.
Daisy-Chaining
To program several MAX4549s, “daisy-chain” the devices
by connecting DOUT of the first device to DIN of the sec-
ond, and so on. The
CS
pins of all devices are connected
together, and data is shifted through the MAX4549 in
series. Twenty-four bits of data per device are required
for proper programming of all devices. When
CS
is
brought high, all devices are updated simultaneously.
Addressable S erial Interfac e
To program several MAX4549s individually using a sin-
gle processor, connect the DIN pins of each MAX4549
together and control
CS
on each MAX4549 separately.
To select a particular device, drive the corresponding
CS
low, clock in the 24-bit command, then drive
CS
high
to execute the command. Typically only one MAX4549
is addressed at a time.
Improving Off-Isolation
To improve off-isolation, connect the S_ input to ground
either directly (DC ground) or through capacitors (AC
ground). Closing S_ then effectively grounds the unused
outputs.
Using the Internal Bias Resistors
Use the internal bias-resistor networks to give the
switch outputs a DC bias when the switch terminals are
AC-coupled. Programming the switches that connect
the bias resistors to the inputs is accomplished via bit
C6 of the command byte. Connect _BIASH and _BIASL
inputs to DC levels (for example, V+ and GND), and
activate the switch connecting the appropriate outputs.
This applies a voltage midway between _BIASH and
_BIASL to the input (refer to Tables 1 and 4, and the
Functional Diagram. To improve crosstalk when using
the bias resistors, connect the MID_ inputs to ground
through capacitors.
Clic kless S witc hing
Audible switching transients (“clicks”) are eliminated in
this mode of operation. When an output is configured as
“clickless,” the gate signal of the switches connected to
the output are controlled with slow-moving voltages. As
a result, the output slew rates are significantly reduced.
Program clickless operation via bit C7 of the command
byte (refer to Tables 1 and 4, and the Functional
Diagram. Each operating switch may draw 2mA during
a transition. When another command is given while a
switch is changing state in the soft mode, the
MAX4548/MAX4549 will complete the previous com-
mand in the hard mode. To avoid this situation, do not
issue a second command until the transition of the
switch is complete.
Power-Up S tate
The MAX4548/MAX4549 feature a preset power-up state.
Refer to Tables 2, 3, and 4 to determine the power-up
state of the devices.
Bypass Capac itors
The MAX4548/MAX4549 have five bypass pins for the
internal bias resistor networks (MID_). The equivalent AC
impedance at these pins is 10k
. To improve crosstalk
performance, bypass MID_ pins with 10μF. For lowest
cost, standard aluminum electrolytic capacitors in parallel
with 0.1μF ceramic chip capacitors perform well in audio
applications. For computer audio applications, a single
1μF capacitor is sufficient. For telecom voice applica-
tions, a 0.1μF capacitor is adequate. For video applica-
tions, bypass MID_ with 0.1μF in parallel with 1000pF.
This provides a low impedance across the entire video
bandwidth.
S erially Controlled, Triple 3x2 Audio/Video
Crosspoint S witc hes
16
______________________________________________________________________________________
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PDF描述 |
|---|---|
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| MAX4549EAX | Serially Controlled, Triple 3x2 Audio/Video Crosspoint Switches |
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| MAX4553CEE | 【15kV ESD-Protected, Quad, Low-Voltage, SPST Analog Switches |
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX4548EAX | 功能描述:视频开关 IC RoHS:否 制造商:Texas Instruments 开关数量:4 开启电阻（最大值）:12 Ohms 传播延迟时间: 开启时间（最大值）: 关闭时间（最大值）: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:WQFN-42 封装:Reel |
| MAX4548EAX+ | 功能描述:视频开关 IC Triple 3x2 A/V Crosspoint Switch RoHS:否 制造商:Texas Instruments 开关数量:4 开启电阻（最大值）:12 Ohms 传播延迟时间: 开启时间（最大值）: 关闭时间（最大值）: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:WQFN-42 封装:Reel |
| MAX4548EAX+T | 功能描述:视频开关 IC Triple 3x2 A/V Crosspoint Switch RoHS:否 制造商:Texas Instruments 开关数量:4 开启电阻（最大值）:12 Ohms 传播延迟时间: 开启时间（最大值）: 关闭时间（最大值）: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:WQFN-42 封装:Reel |
| MAX4548EAX+W | 制造商:Maxim Integrated Products 功能描述:SERIALLY CONTROLLED TRIPLE 3X2 AUDIO/VIDEO CROSSPOINT SWITCH - Rail/Tube |
| MAX4548EAX-T | 功能描述:视频开关 IC RoHS:否 制造商:Texas Instruments 开关数量:4 开启电阻（最大值）:12 Ohms 传播延迟时间: 开启时间（最大值）: 关闭时间（最大值）: 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:WQFN-42 封装:Reel |
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