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参数资料
| 型号： | SPX1581U5-3.3 |
| 元件分类： | 固定正电压单路输出LDO稳压器 |
| 英文描述： | 3.3 V FIXED POSITIVE LDO REGULATOR, 0.5 V DROPOUT, PSFM5 |
| 封装： | TO-220AC, 5 PIN |
| 文件页数： | 4/7页 |
| 文件大小： | 89K |
| 代理商： | SPX1581U5-3.3 |
4
Date: 1/21/05
SPX1581 5A Ultra Low Dropout Voltage Regulator
Copyright 2005 Sipex Corporation
Adjustable Regulator Design
1.25V reference voltage is being developed be-
tween the SENSE pin and the ADJ pin of the
SPX1581. Adding two external resistors (see fig
1.) will allow setting the output voltage from
1.25V to 6V. R1 is chosen so that this current is
specified minimum load current of 10mA. R2 is
given by the formula: VOUT = VREF (1+ R2/R1)
+ IADJ (R2). The current flowing from the ADJ
pin is typicaly 50
A. This ADJ pin contributes
to the final VOUT but is usually neglected.
Connecting the sense pin to the top of the resis-
tor divider will improve load regualtion.
Lowering Noise
Using the SENSE pin to Kelvin the load will
increase accuracy of the output voltage during
load regulation. For the fixed voltage device,
adding a capacitor at the GND pin will improve
transient response. This capacitor is chosen in
the range of 1
F to 0.1F and will depend on the
amount of output capacitance in the system.
APPLICATION NOTES
A typical application would use 5V for VIN and
3.3V for VCTRL from a motherboard power
supply to provide a nominal 2.5V output. Using
the sense pin allows Kelvin measure the output,
reducing resistance-associated errors.
The SPX1581 can power the 2.5V core voltage
for microprocessors such as a PentiumTM,
P55CTM, AMD5k86TM and K6TM and the IBM
PowerPCTM 603EV and 604EV processors.
Power sequencing of VIN and VCTRL is re-
quired. Apply VIN before VCTRL for proper
operation
The SPX1581 is designed as a high performance
and low cost solution for application requiring a
lower dropout than traditional NPN regulators.
The SPX1581 uses a separate input voltage VCTRL
( VCTRL ≥ VOUT + 1.3V) to minimize the dropout
voltage. This allows the 2.5V power for the load
to come from a 3.3V system supply.
As added benefit this will reduce the heat dissi-
pation*, and lower heatsink and cooling fan cost.
* The reduction of heat dissipation is a result of the
increase of the regulator efficiency (efficiency = V
OUT/VIN).
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相关代理商/技术参数 |
参数描述 |
|---|---|
| SPX1581U5-L | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SPX1581U5-L-2-5 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SPX1581U5-L-3-3 | 制造商:Rochester Electronics LLC 功能描述: 制造商:Exar Corporation 功能描述: |
| SPX1582 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:3A Ultra Low Dropout Voltage Regulator |
| SPX1582_06 | 制造商:SIPEX 制造商全称:Sipex Corporation 功能描述:3A Ultra Low Dropout Voltage Regulator |
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