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參數(shù)資料
| 型號： | TPS2201IDB |
| 廠商： | TEXAS INSTRUMENTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO30 |
| 封裝： | GREEN, SSOP-30 |
| 文件頁數(shù)： | 7/23頁 |
| 文件大?。?/td> | 430K |
| 代理商： | TPS2201IDB |
TPS2201
DUAL-SLOT PC CARD POWER-INTERFACE SWITCHES
FOR PARALLEL PCMCIA CONTROLLERS
SLVS094C – AUGUST 1994 – REVISED JANUARY 2001
15
POST OFFICE BOX 655303
DALLAS, TEXAS 75265
APPLICATION INFORMATION
designing around 1-A delivery (continued)
Calculating the rDS(on) necessary to support a 100 mV or 198 mV switch loss, using R = E/I and setting I = 1 A,
the 5-V and 3.3-V switches would need to be 100 m
and 198 m respectively. One solution would be to pay
for a more expensive switch with lower rDS(on). A second, less expensive approach is to increase the headroom
of the power supply—for example, to increase the 5-V supply 1.5% or to 5.075
±2%. Working through the
numbers once more, the 2% for the regulator plus 1% for etch and terminal losses leaves 97% or 4.923 V. The
allowable voltage loss across the power distribution switch is now 4.923 V minus 4.750 V or 173 mV. Therefore,
a switch with 173 m
or less could deliver 1 A or greater. Setting the power supply high is a common practice
for delivering voltages to allow for system switch, connector, and etch losses and has a minimal effect on overall
battery life. In the example above, setting the power supply 1.5% high would only decrease a 3-hour battery
life by approximately 2.7 minutes, trivial when compared with the decrease in battery life when running a 5-W
PC Card.
heat dissipation
A greater concern in delivering 1 A or 5 W is the ability of the host to dissipate the heat generated by the PC
Card. For desktop computers the solution is simpler: locate the PC Card cage such that it receives convection
cooling from the forced air of the fan. Notebooks and other handheld equipment will not be able to rely on
convection, but must rely on conduction of heat away from the PC Card through the rails into the card cage.
This is difficult because PC Card/card cage heat transfer is very poor. A typical design scenario would require
the PC Card to be held at 60
°C maximum with the host platform operating as high as 50°C. Preliminary testing
reveals that a PC Card can have a 20
°C rise, exceeding the 10°C differential in the example, when dissipating
less than 2 W of continuous power. The 60
°C temperature was chosen because it is the maximum operating
temperature allowable by PC Card specification. Power handling requirements and temperature rises are topics
of concern and are currently being addressed by the PCMCIA committee.
overcurrent and overtemperature protection
PC Cards are inherently subject to damage that can result from mishandling. Host systems require protection
against short-circuited cards that could lead to power supply or PCB-trace damage. Even systems sufficiently
robust to withstand a short circuit would still undergo rapid battery discharge into the damaged PC Card,
resulting in the rather sudden and unacceptable loss of system power. This can be particularly frustrating to the
consumer who has already experienced problems with shortened battery life due to improper Nicad conditioning
or memory effect. Most hosts include fuses for protection. The reliability of fused systems is poor, though, as
blown fuses require troubleshooting and repair, usually by the manufacturer. The TPS2201 takes a two-pronged
approach to overcurrent protection. First, instead of fuses, sense FETs monitor each of the power outputs.
Excessive current generates an error signal that linearly limits the output current, preventing host damage or
failure. Sense FETs, unlike sense resistors or polyfuses, have the added advantage that they do not add to the
series resistance of the switch and thus produce no additional voltage losses. Second, when an overcurrent
condition is detected, the TPS2201 asserts a signal at OC that can be monitored by the microprocessor to initiate
diagnostics and/or send the user a warning message. In the event that an overcurrent condition persists,
causing the IC to exceed its maximum junction temperature, thermal-protection circuitry engages, shutting
down all power outputs until the device cools to within a safe operating region.
12-V supply not required
Most PC Card switches use the externally supplied 12-V Vpp power for switch-gate drive and other chip
functions, requiring that it be present at all times. The TPS2201 offers considerable power savings by using an
internal charge pump to generate the required higher voltages from the 5-V VDD supply; therefore, the external
12-V supply can be disabled except when needed for flash-memory functions, thereby extending battery
lifetime. Additional power savings are realized by the TPS2201 during a software shutdown, in which quiescent
current drops to a maximum of 1
A.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| TPS2201IDBG4 | 功能描述:電源開關(guān) IC - 配電 1A Dual-Slot PC Card Power Switch RoHS:否 制造商:Exar 輸出端數(shù)量:1 開啟電阻（最大值）:85 mOhms 開啟時(shí)間（最大值）:400 us 關(guān)閉時(shí)間（最大值）:20 us 工作電源電壓:3.2 V to 6.5 V 電源電流（最大值）: 最大工作溫度:+ 85 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:SOT-23-5 |
| TPS2201IDBR | 功能描述:熱插拔功率分布 1A Dual-Slot PC Card Power Switch RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| TPS2201IDBRG4 | 功能描述:熱插拔功率分布 1A Dual-Slot PC Card Power Switch RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
| TPS2201IDFLE | 制造商:Texas Instruments 功能描述:PCMCIA SWITCHING CIRCUIT, 30 Pin, Plastic, SOP |
| TPS2201IDFR | 功能描述:熱插拔功率分布 1A Dual-Slot PC Card Power Switch RoHS:否 制造商:Texas Instruments 產(chǎn)品:Controllers & Switches 電流限制: 電源電壓-最大:7 V 電源電壓-最小:- 0.3 V 工作溫度范圍: 功率耗散: 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:MSOP-8 封裝:Tube |
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