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參數(shù)資料
| 型號(hào)： | MAX3221 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | 1μA Supply-Current, True +3V to +5.5V RS-232 Transceivers with AutoShutdown(3V~5.5V,自動(dòng)關(guān)閉方式接收器有效,120kbps，RS-232收發(fā)器) |
| 中文描述： | 1µA電源電流、+3V至+5.5V、真RS-232收發(fā)器，帶有AutoShutdown |
| 文件頁數(shù)： | 7/16頁 |
| 文件大小： | 203K |
| 代理商： | MAX3221 |
M
1μA S upply Current, True +3V to +5.5V RS -232
Transc eivers with AutoS hutdown
_______________________________________________________________________________________
7
AutoS hutdown
A 1μA supply current is achieved with Maxim’s new Auto-
Shutdown feature, which operates when FORCEON is low
and
FORCEOFF
is high. When the MAX3221/MAX3223/
MAX3243 sense no valid signal levels on all receiver
inputs for 30μs, the on-board power supply and drivers
are shut off, reducing supply current to 1μA. This occurs
if the RS-232 cable is disconnected or the connected
peripheral transmitters are turned off. The system turns on
again when a valid level is applied to any RS-232 receiver
input. As a result, the system saves power without
changes to the existing BIOS or operating system. When
using AutoShutdown, the
INVALID
output is high when
the device is on and low when the device is shut down.
Because
INVALID
indicates the receiver inputs’ condition,
it can be used in any mode (Figure 3).
Table 2 and Figure 3c summarize the MAX3221/
MAX3223/MAX3243 operating modes. FORCEON and
FORCEOFF
override the automatic circuitry and force
the transceiver into its normal operating state or into its
low-power standby state. When neither control is assert-
ed, the IC selects between these states automatically
based on receiver input levels. Figures 3a, 3b, and 5a
depict valid and invalid RS-232 receiver levels.
A mouse or other system with AutoShutdown may need
time to wake up. Figure 4 shows a circuit that forces the
transmitters on for 100ms, allowing enough time for the
Table 1a. MAX3221/MAX3223
FORCEOFF
and
Enable Control Truth Table
Table 1b. MAX3243
FORCEOFF
Control
Truth Table
Active*
1
1
Active*
0
1
FORCEOFF
High-Z
1
0
High-Z
0
0
T_OUT
EN
High-Z
Active
High-Z
Active
R_OUT
+0.3V
-0.3V
INVALID
TOMAX32_ _
POWER SUPPLY
AND TRANSMITTERS
COUNTER
R
R_IN
* TRANSMITTERS ARE DISABLED, REDUCING SUPPLY CURRENT TO1
μ
A IF
ALL RECEIVER INPUTS ARE BETWEEN +0.3V AND -0.3V FOR
AT LEAST
30
μ
s.
30μs
Active*
1
High-Z
0
T_OUT
FORCEOFF
Active*
High-Z
R_OUT
Active
Active
R2OUTB
Figure 3a. MAX32_ _ Entering 1μA Supply Mode via
AutoShutdown
*
Note:
If the part is in AutoShutdown mode (
FORCEOFF
= V
CC
,
FORCEON = GND), it is shut down if no valid RS-232
levels are present on all receiver inputs.
FORCEON
MASTER SHDN LINE
0.1μF
1M
FORCEOFF
MAX3221
MAX3223
MAX3243
POWER
MANAGEMENT
UNIT
Figure 4. AutoShutdown with Initial Turn-On to Wake Up a
Mouse or Another System
+2.7V
-2.7V
INVALID
TOMAX32_ _
POWER SUPPLY
R_IN
* TRANSMITTERS ARE ENABLED IF:
ANY RECEIVER INPUT IS GREATER THAN +2.7V OR LESS THAN -2.7V.
ANY RECEIVER INPUT HAS BEEN BETWEEN +0.3V AND -0.3V FOR
LESS THAN
30
μ
s.
30μs
COUNTER
R
Figure 3b. MAX32_ _ with Transmitters Enabled Using
AutoShutdown
FORCEOFF
POWER DOWN
INVALID
FORCEON
INVALID IS AN INTERNALLY GENERATED SIGNAL
THAT IS USED BY THE AUTOSHUTDOWN LOGIC
AND APPEARS AS AN OUTPUT OF THE DEVICE.
POWER DOWN IS ONLY AN INTERNAL SIGNAL.
IT CONTROLS THE OPERATIONAL STATUS OF
THE TRANSMITTERS AND THE POWER SUPPLIES.
Figure 3c. AutoShutdown Logic
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX3221CAE | 功能描述:RS-232接口集成電路 RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝: |
| MAX3221CAE+ | 功能描述:RS-232接口集成電路 1uA 3-5.5V Tcvr w/AutoShutdown RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝: |
| MAX3221CAE+T | 功能描述:RS-232接口集成電路 1uA 3-5.5V Tcvr w/AutoShutdown RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝: |
| MAX3221CAE-T | 功能描述:RS-232接口集成電路 RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝: |
| MAX3221CDB | 功能描述:RS-232接口集成電路 3-5.5V Single-Ch Line Drvr/Rcvr RoHS:否 制造商:Exar 數(shù)據(jù)速率:52 Mbps 工作電源電壓:5 V 電源電流:300 mA 工作溫度范圍:- 40 C to + 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:LQFP-100 封裝: |
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