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參數(shù)資料
| 型號(hào)： | US1050CM |
| 廠商： | Unisem Group |
| 英文描述： | 5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| 中文描述： | 第5A低壓差型正，可調(diào)式穩(wěn)壓器 |
| 文件頁(yè)數(shù)： | 6/7頁(yè) |
| 文件大小： | 52K |
| 代理商： | US1050CM |
US1050
2-38
Rev. 1.3
10/27/00
The Sanyo MVGX series is a good choice to achieve
both price and performance goals.The 6MV1500GX ,
1500uF, 6.3V has an ESR of less than 36 m
typ .
Selecting 5 of these capacitors in parallel has an ESR
of
≈
7.2 m
which achieves our design goal.
The next step is to calculate the drop due to the capaci-
tance discharge and make sure that this drop in voltage
is less than the selected ESL drop in the previous step.
2) The output capacitance is 5X1500 uF = 7500uF
To set the output DC voltage, we need to select R1 and
R2 :
3) Assuming
R1=121
, 0.1%
Select
R2=218
,0.1%
Selecting both R1 and R2 resistors to be 0.1% toler-
ance, results in the least amount of error introduced by
the resistor dividers leaving
≈
±
1.3% error budget for
the US1050 reference which is within the initial accu-
racy of the device.
Finally , the input capacitor is selected as follows :
4) Assuming that the input voltage can drop 150mV be-
fore the main power supply responds, and that the main
power supply response time is
≈
50 uSec, then the mini-
mum input capacitance for a 4.6A load step is given by
output voltage of the regulator. As shown in this figure,
the ESR of the output capacitor produces an instanta-
neous drop equal to the (
V
ESR
=ESR*
I) and the ESL
effect will be equal to the rate of change of the output
current times the inductance of the capacitor. (
V
ESL
=L*
I/
t) . The output capacitance effect is a droop in
the output voltage proportional to the time it takes for
the regulator to respond to the change in the current ,
(
V
C
=
t *
I / C ) where
t is the response time of the
regulator.
Figure 4 - Typical Regulator response to the fast load
current step.
An example of a regulator design to meet the Intel
P54C
VRE specification is given below .
Assume the specification for the processor as shown in
Table 1:
Type of Vout Imax Max Allowed
Processor Nominal Output Tolerance
Intel-P54C VRE 3.50 V 4.6 A
±
100 mV
Table 1 - Processr Specification
The first step is to select the voltage step allowed in the
output due to the output capacitor’s ESR :
1) Assuming the regulator’s initial accuracy plus the re-
sistor divider tolerance is
≈
±
53 mV (
±
1.5% of 3.5V nomi-
nal) ,then the total step allowed for the ESR and the
ESL, is
47 mV .
Assuming that the ESL drop is
10mV ,the remaining
ESR step will be
37 mV . Therefore the output capaci-
tor ESR must be :
V
t
I
C
Where :
t
=2 uS is t
he regulator response time
C
=
×
=
=
2 4 6
7500
. mV
.
R
V
V
OUT
REF
2
1
121
35
125
.
1
121 21.
×
=
×
=
.
C
IN
=
.
=
46 50
015
1530
.
F
V
ESR
V
ESL
V
C
T
LOAD
CURRENT
LOAD CURRENT RISE TIME
1050plt1-1.0
ESR
≤
=
37
46
.
8
m
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| US1050CP | 5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1050CT | 5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1075 | 7.5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1075CM | 7.5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1075CP | 7.5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| US1050CP | 制造商:UNISEM 制造商全稱:UNISEM 功能描述:5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1050CT | 制造商:UNISEM 制造商全稱:UNISEM 功能描述:5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1075 | 制造商:UNISEM 制造商全稱:UNISEM 功能描述:7.5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1075CM | 制造商:UNISEM 制造商全稱:UNISEM 功能描述:7.5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
| US1075CP | 制造商:UNISEM 制造商全稱:UNISEM 功能描述:7.5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR |
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