參數(shù)資料
型號: MAX3291ESD
廠商: Maxim Integrated Products
文件頁數(shù): 5/16頁
文件大?。?/td> 0K
描述: IC TXRX RS485/422 5-10MBPS14SOIC
產(chǎn)品培訓(xùn)模塊: Lead (SnPb) Finish for COTS
Obsolescence Mitigation Program
標(biāo)準(zhǔn)包裝: 50
類型: 收發(fā)器
驅(qū)動器/接收器數(shù): 1/1
規(guī)程: RS422,RS485
電源電壓: 4.75 V ~ 5.25 V
安裝類型: 表面貼裝
封裝/外殼: 14-SOIC(0.154",3.90mm 寬)
供應(yīng)商設(shè)備封裝: 14-SOIC
包裝: 管件
MAX3291/MAX3292
RS-485/RS-422 Transceivers with Preemphasis
for High-Speed, Long-Distance Communication
______________________________________________________________________________________
13
DI
RO
RE
Z
Y
B
A
YB
A
RE
RO
DI
DE
D
R
Y
B
A
R = ZO
D
R
MAX3291
MAX3292
Figure 19. Typical Half-Duplex RS-485 Network
3) Don’t overload the cable with too many receivers.
Even though the MAX3291/MAX3292 receives pre-
sent only 1/4-unit load, placing 128 receivers on the
cable will attenuate the signal if spaced out along
the cable and, in addition, cause reflections if
clumped in one spot. The MAX3291/MAX3292 suc-
cessfully drive the cables to correct RS-485/RS-422
levels with 128 receivers, but the preemphasis
effect is significantly diminished.
The MAX3291/ MAX3292 are centered for a load imped-
ance of 54
, which corresponds to the parallel combina-
tion of the cable impedance and termination resistors. If
your cable impedance deviates somewhat from this
value, you still get the preemphasis effect (although the
ideal preemphasis time, tPRE, may need adjustment).
However, if your cable impedance is significantly differ-
ent, the preemphasis ratio DPER changes, resulting in
significantly less preemphasis. Determine the preempha-
sis ratio versus load by referring to the Driver Differential
Output Voltage vs. RDIFF graph in the Typical Operating
Characteristics. Read the strong and normal levels from
the graph (remember that the horizontal units are half
your cable impedance) and divide the two numbers to
get DPER (DPER = VSTRONG / VNORMAL = VODP / VOD).
Figures 19 and 20 show typical network application cir-
cuits with proper termination.
Preemphasis at Low Data Rates
(MAX3292)
At low data rates (<1Msps), preemphasis operation is
not guaranteed because it is highly dependent on the
system power-supply noise. Minimize this noise by
increasing bypass capacitance and using a power
supply with a fast transient response.
R = ZO
R
D
RO
RE
DE
DI
A
B
Y
R = ZO
DI
RO
DE
RE
Z
Y
AA
A
BB
B
D
R
MAX3291
MAX3292
NOTE: RE AND DE ON.
Figure 20. Typical Full-Duplex RS-485 Network
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MAX3291ESD+T 功能描述:RS-422/RS-485 接口 IC For Long-Distance Communication RoHS:否 制造商:Maxim Integrated 數(shù)據(jù)速率:1136 Kbps 工作電源電壓:3 V to 5.5 V 電源電流:5.9 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-28 封裝:Tube
MAX3291ESD-T 功能描述:RS-422/RS-485 接口 IC RoHS:否 制造商:Maxim Integrated 數(shù)據(jù)速率:1136 Kbps 工作電源電壓:3 V to 5.5 V 電源電流:5.9 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-28 封裝:Tube
MAX3292CPD 功能描述:RS-422/RS-485 接口 IC RoHS:否 制造商:Maxim Integrated 數(shù)據(jù)速率:1136 Kbps 工作電源電壓:3 V to 5.5 V 電源電流:5.9 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOIC-28 封裝:Tube
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