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G570SA 参数 Datasheet PDF下载

G570SA图片预览
型号: G570SA
PDF下载: 下载PDF文件 查看货源
内容描述: 双槽PCMCIA / CardBus的电源控制器 [Dual-Slot PCMCIA/CardBus Power Controller]
分类和应用: 电源电路电源管理电路光电二极管控制器PC
文件页数/大小: 14 页 / 219 K
品牌: GMT [ GLOBAL MIXED-MODE TECHNOLOGY INC ]
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Global Mixed-mode Technology Inc.  
G570  
resistance of the switch and thus produce no addi-  
tional voltage losses. Second, when an overcurrent  
condition is detected, the G570 asserts a signal at  
Application Information  
Overview  
PC Cards were initially introduced as a means to add  
EEPROM (flash memory) to portable computers with  
limited on-board memory. The idea of add-in cards  
quickly took hold; modems, wireless LANs, Global  
Positioning Satellite (GPS), multimedia, and hard-disk  
versions were soon available. As the number of PC  
Card applications grew, the engineering community  
quickly recognized the need for a standard to ensure  
compatibility across platforms. To this end, the  
PCMCIA was established, comprised of members  
from leading computer, software, PC Card, and  
semiconductor manufactures. One key goal was to  
realize the “plug-and play” concept. Cards and hosts  
from different vendors should be compatibleable to  
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  
activates, shutting down all power outputs until the  
device cools to within a safe operating region.  
12V Supply Not Required  
Most PC Card switches use the externally supplied  
12V VPP power for switch-gate drive and other chip  
functions, which requires that power be present at all  
times. The G570 offers considerable power savings by  
using an internal charge pump to generate the re-  
quired higher voltages from 5V or 3.3V input; therefore,  
the external 12V supply can be disable except when  
needed for flash-memory functions, thereby extending  
battery lifetime. Do not ground the 12V input if the 12V  
input is not used. Additional power savings are real-  
ized by the G570 during a software shutdown in which  
quiescent current drops to a typical of 2µA.  
communicate with one another transparently.  
PC Card Power Specification  
System compatibility also means power compatibility.  
The most current set of specifications (PC Card Stan-  
dard) set forth by the PCMCIA committee states that  
power is to be transferred between the host and the  
card through eight of the 68 terminals of the PC Card  
connector. This power interface consists of two VCC,  
two VPP, and four ground terminals. Multiple VCC and  
ground terminals minimize connector-terminal and line  
resistance. The two VPP terminals were originally  
specified as separate signals but are commonly tied  
together in the host to form a single node to minimize  
voltage losses. Card primary power is supplied  
through the VCC terminals; flash-memory programming  
and erase voltage is supplied through the VPP termi-  
nals.  
3.3V Low Voltage Mode  
The G570 operates in 3.3V low voltage mode when  
3.3V is the only available input voltage (VI(5V)=0).This  
allows host and PC Cards to be operated in low power  
3.3V only modes such as sleep modes or pager  
modes. Note that in this operation mode, the G570  
derives its bias current from the 3.3V input pin and  
only 3.3V can be delivered to the Card. The 3.3V  
switch resistance increases, but the added switch re-  
sistance should not be critical, because only a small  
amount of current is delivered in this mode.  
Overcurrent and Over-Temperature Protection  
PC Cards are inherently subject to damage that can  
result from mishandling. Host systems require protec-  
tion against short-circuited cards that could lead to  
power supply or PCB-trace damage. Even systems  
robust enough 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. Most hosts include fuses for  
protection. However, the reliability of fused systems is  
poor, as blown fuses require troubleshooting and re-  
pair, usually by the manufacturer.  
Voltage Transitioning Requirement  
PC Cards, like portables, are migrating from 5V to  
3.3V to minimize power consumption, optimize board  
space, and increase logic speeds. The G570 is de-  
signed to meet all combinations of power delivery as  
currently defined in the PCMCIA standard. The latest  
protocol accommodates mixed 3.3V/5V systems by  
first powering the card with 5V, then polling it to de-  
termine its 3.3V compatibility. The PCMCIA specifica-  
tion requires that the capacitors on 3.3V compatible  
cards be discharged to below 0.8 V before applying  
3.3V power. This ensures that sensitive 3.3V circuitry  
is not subjected to any residual 5V charge and func-  
tions as a power reset. The G570 offer a selectable  
The G570 takes a two-pronged approach to overcur-  
rent 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 an  
added advantage in that they do not add to the series  
V
CC and VPP ground state, in accordance with PCMCIA  
3.3V/5V switching specifications, to fully discharge the  
card capacitors while switching between VCC voltage.  
Ver 1.0  
Nov 09, 2000  
TEL: 886-3-5788833  
http://www.gmt.com.tw  
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