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参数资料
| 型号： | ISL4221EIRZ |
| 厂商： | Intersil |
| 文件页数： | 14/14页 |
| 文件大小： | 0K |
| 描述： | IC TXRX 1TX/1RX 3V RS-232 16-QFN |
| 标准包装： | 60 |
| 类型： | 收发器 |
| 驱动器/接收器数： | 1/1 |
| 规程： | RS232 |
| 电源电压： | 2.7 V ~ 5.5 V |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-VQFN 裸露焊盘 |
| 供应商设备封装： | 16-QFN-EP（5x5） |
| 包装： | 管件 |
9
FN6045.6
May 13, 2010
Automatic Power-down (Excluding ISL3232E)
Even greater power savings is available by using the
automatic power-down function. When no valid RS-232
voltages (see Figure 6) are sensed on any receiver input for
30s, the charge pump and transmitters power-down,
thereby reducing supply current to 150nA. Invalid receiver
levels occur whenever the driving peripheral’s outputs are
shut off (powered down) or when the RS-232 interface cable
is disconnected. The ISL4221E, ISL4223E powers back up
whenever it detects a valid RS-232 voltage level on any
receiver input. This automatic power-down feature provides
additional system power savings without changes to the
existing operating system.
Automatic power-down operates when the FORCEON input is
low, and the FORCEOFF input is high. Tying FORCEON high
disables automatic power-down, but manual power-down is
always available via the overriding FORCEOFF input. Table 2
summarizes the automatic power-down functionality.
Some applications may need more time to wake up from
shutdown. If automatic power-down is being utilized, the
RS-232 device will re-enter power-down if valid receiver
levels aren’t reestablished within 30s of the ISL4221E,
ISL4223E powering up. Figure 5 illustrates a circuit that
keeps the ISL4221E, ISL4223E from initiating automatic
power-down for 100ms after powering up. This gives the
slow-to-wake peripheral circuit time to re-establish valid
RS-232 output levels.
The time to recover from automatic power-down mode is
typically 100s.
INVALID Output (Excluding ISL3232E)
The INVALID output always indicates whether or not a valid
RS-232 signal (see Figure 6) is present at any of the
receiver inputs (see Table 2), giving the user an easy way to
determine when the interface block should power down.
Invalid receiver levels occur whenever the driving
peripheral’s outputs are shut off (powered down) or when the
RS-232 interface cable is disconnected. In the case of a
disconnected interface cable where all the receiver inputs
are floating (but pulled to GND by the internal receiver pull
down resistors), the INVALID logic detects the invalid levels
and drives the output low. The power management logic
then uses this indicator to power-down the interface block.
Reconnecting the cable restores valid levels at the receiver
inputs, INVALID switches high, and the power management
logic wakes up the interface block. INVALID can also be
used to indicate the DTR or RING INDICATOR signal, as
long as the other receiver inputs are floating, or driven to
GND (as in the case of a powered down driver).
INVALID switches low after invalid levels have persisted on all
of the receiver inputs for more than 30s (see Figure 7).
INVALID switches back high 1s after detecting a valid
RS-232 level on a receiver input. INVALID operates in all
modes (forced or automatic power-down, or forced on), so it is
also useful for systems employing manual power-down
circuitry. When automatic power-down is utilized, INVALID = 0
indicates that the ISL4221E, ISL4223E is in power-down
mode.
Capacitor Selection
The charge pumps require 0.1F, or greater, capacitors for
proper operation. Increasing the capacitor values (by a
factor of 2) reduces ripple on the transmitter outputs and
slightly reduces power consumption.
When using minimum required capacitor values, make sure
that capacitor values do not degrade excessively with
temperature. If in doubt, use capacitors with a larger nominal
value. The capacitor’s equivalent series resistance (ESR)
usually rises at low temperatures and it influences the
amount of ripple on V+ and V-
.
FIGURE 6. DEFINITION OF VALID RS-232 RECEIVER LEVELS
0.3V
-0.3V
-2.7V
2.7V
INVALID LEVEL - POWER-DOWN OCCURS AFTER 30s
VALID RS-232 LEVEL - ISL4221E, ISL4223E IS ACTIVE
INDETERMINATE - POWER-DOWN MAY OR
MAY NOT OCCUR
RECEIVER
INPUTS
TRANSMITTER
OUTPUTS
INVALID
OUTPUT
V+
VCC
0
V-
VCC
0
tINVL
tINVH
INVALID
REGION
}
FIGURE 7. AUTOMATIC POWER-DOWN AND INVALID
TIMING DIAGRAMS
AUTOPWDN
PWR UP
ISL3232E, ISL4221E, ISL4223E
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相关代理商/技术参数 |
参数描述 |
|---|---|
| ISL4221EIRZ-T | 功能描述:IC XMITTER/RCVR ESD RS232 16-QFN RoHS:是 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 类型:发射器 驱动器/接收器数:4/0 规程:RS422，RS485 电源电压:4.75 V ~ 5.25 V 安装类型:表面贴装 封装/外壳:16-SOIC（0.154"，3.90mm 宽） 供应商设备封装:16-SOIC 包装:带卷 (TR) |
| ISL4223E | 制造商:INTERSIL 制造商全称:Intersil Corporation 功能描述:QFN Packaged, 【15kV ESD Protected, +2.7V to +5.5V, 150nA, 250kbps, RS-232 Transmitters/Receivers |
| ISL4223EIR | 功能描述:IC TXRX RS232 2.7-5.5V ESD 20QFN RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 标准包装:1,000 系列:- 类型:收发器 驱动器/接收器数:2/2 规程:RS232 电源电压:3 V ~ 5.5 V 安装类型:表面贴装 封装/外壳:16-SOIC（0.295"，7.50mm 宽） 供应商设备封装:16-SOIC 包装:带卷 (TR) |
| ISL4223EIR-T | 功能描述:IC TXRX 2TX/2RX 3V RS-232 20-QFN RoHS:否 类别:集成电路 (IC) >> 接口 - 驱动器，接收器，收发器 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:25 系列:- 类型:收发器 驱动器/接收器数:2/2 规程:RS232 电源电压:4.5 V ~ 5.5 V 安装类型:通孔 封装/外壳:16-DIP（0.300"，7.62mm） 供应商设备封装:16-PDIP 包装:管件 |
| ISL4223EIRZ | 功能描述:RS-232接口集成电路 3V RS-232 2TX/2RX TRANSC 20LD 5X5 RoHS:否 制造商:Exar 数据速率:52 Mbps 工作电源电压:5 V 电源电流:300 mA 工作温度范围:- 40 C to + 85 C 安装风格:SMD/SMT 封装 / 箱体:LQFP-100 封装: |
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