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參數(shù)資料
| 型號： | LX1664CD |
| 廠商： | MICROSEMI CORP-ANALOG MIXED SIGNAL GROUP |
| 元件分類： | 穩(wěn)壓器 |
| 英文描述： | DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
| 中文描述： | 1.5 A SWITCHING CONTROLLER, 200 kHz SWITCHING FREQ-MAX, PDSO16 |
| 封裝： | ROHS COMPLIANT, PLASTIC, SOIC-16 |
| 文件頁數(shù)： | 15/17頁 |
| 文件大?。?/td> | 354K |
| 代理商： | LX1664CD |
LX1664/1664A, LX1665/65A
15
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LINEAR REGULATOR
Referring to the front page Product Highlight, a schematic is
presented which uses a MOSFET as a series pass element for a
linear regulator. The MOSFET is driven by the LX1664 controller,
and down-converts a +5V or +3.3V supply to the desired V
level, between 1.5 & 3.5V, as determined by the feedback
resistors.
The current available from the Linear regulator is dictated by
the supply capability, as well as the MOSFET ratings, and will
typically lie in the 3-5 ampere range. This output is well suited
for I/O buffers, memory, chipset and other components. Using
3.3V supply to convert to 1.5V for GTL+ Bus will significantly
reduce heat dissipation in the MOSFET.
MOSFET Comments
Heatsinking the MOSFET becomes important, since the linear
stage output current could approach 5 amperes in some applica-
tions. Since there are no switching losses, power dissipation in
the MOSFET is simply defined by
P
= (V
- V
) * I
output
current. This means that a +5V
to +3.3V
at 5A will require that
the MOSFET dissipate
(5-3.3) * 5 = 8.5 watts
. This amount of
power in a MOSFET calls for a heatsink, which will be the same
physical size as that required for a monolithic LDO, such as the
LX8384 device.
The dropout voltage for the linear regulator stage is the product
of
R
ON * I
. Using a 2SK1388 device at 5A, the dropout
voltage will be (worst case) 37 milliohms x 5A = 185mV.
Note that the R
ON of the (linear regulator) MOSFET does not
affect heat dissipation, only dropout voltage. For reasons of
economy, a FET with a higher resistance can be chosen for the
linear regulator, e.g. 2SK1388 or IRLZ44.
LINEAR REGULATOR
(continued)
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TABLE 5 - Linear Regulator MOSFET Selection Guide
FIGURE 13
—
Typical Transient Response
Avoiding Crosstalk
To avoid a load transient on the switching output affecting the
linear regulator, follow these guidelines:
1) Separate 5V supply traces to switching & linear FETs as
much as possible.
2) Place capacitor C
9
as close to drain of Q
4
as possible.
Typical transient response is shown in Figure 13.
Channel 2
= Linear Regulator Output.
Set point = 3.3V @ 2A (20mV/div.)
Channel 4
= Switching Regulator Output.
V
set point = 2.8V
Channel 3
= Switching Regulator Load Current
Transient 0 - 13A
Output Voltage Setting
As shown in Application Information Figures 6-9, two resistors (R
5
& R
6
) set the linear regulator stage output voltage:
V
OUT
= 1.5 * (R
5
+ R
6
) / R
6
As an example, to set resistor magnitudes, assume a desired
V
OUT
of 3.3 volts:
1.5 * (12.1k + 10k) / 10k = 3.3 volts (approximately)
In general, the divider resistor values should be in the vicinity
of 10-12k ohm for optimal noise performance. Please refer to
Table 6.
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| LX1664CN | DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
| LX1665 | DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
| LX1665A | DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
| LX1665ACDW | DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
| LX1665ACN | DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| LX1664CN | 功能描述:IC PWM DUAL OUT 5BIT DAC 16DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
| LX1665 | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
| LX1665A | 制造商:MICROSEMI 制造商全稱:Microsemi Corporation 功能描述:DUAL OUTPUT PWM CONTROLLERS WITH 5-BIT DAC |
| LX1665ACDW | 功能描述:IC PWM DUAL OUT 5BIT DAC 18SOIC RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
| LX1665ACN | 功能描述:IC PWM DUAL OUT 5BIT DAC 18DIP RoHS:是 類別:集成電路 (IC) >> PMIC - 穩(wěn)壓器 - 專用型 系列:- 產(chǎn)品培訓(xùn)模塊:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 標(biāo)準(zhǔn)包裝:2,000 系列:- 應(yīng)用:電源，ICERA E400，E450 輸入電壓:4.1 V ~ 5.5 V 輸出數(shù):10 輸出電壓:可編程 工作溫度:-40°C ~ 85°C 安裝類型:表面貼裝 封裝/外殼:42-WFBGA，WLCSP 供應(yīng)商設(shè)備封裝:42-WLP 包裝:帶卷 (TR) |
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