Moteur de recherche de fiches techniques de composants électroniques
  French  ▼

Delete All
ON OFF
ALLDATASHEET.FR

X  

Preview PDF Download HTML

US1050 Fiches technique(PDF) 6 Page - UNISEM

No de pièce US1050
Description  5A LOW DROPOUT POSITIVE ADJUSTABLE REGULATOR
Download  7 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricant  UNISEM [UNISEM]
Site Internet  
Logo UNISEM - UNISEM

US1050 Fiches technique(HTML) 6 Page - UNISEM

  US1050 Datasheet HTML 1Page - UNISEM US1050 Datasheet HTML 2Page - UNISEM US1050 Datasheet HTML 3Page - UNISEM US1050 Datasheet HTML 4Page - UNISEM US1050 Datasheet HTML 5Page - UNISEM US1050 Datasheet HTML 6Page - UNISEM US1050 Datasheet HTML 7Page - UNISEM  
Zoom Inzoom in Zoom Outzoom out
 6 / 7 page
background image
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 mwhich 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 equalto the (
∆VESR=ESR*∆I) and the ESL
effect will be equal to the rate of change of the output
current times the inductance of the capacitor. (
∆VESL
=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 ,
(
∆VC = ∆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
he regulator response time
C
=
×
= ×
=
2 4 6
7500
12
.
. mV
=2 uS is t
R
V
V
OUT
REF
2
1
121
3 5
125
1
121 217 8
=


×
=


×
=
.
.
.
CIN
=
×
=
4 6 50
0 15
1530
.
.
F
µ
V ESR
V ESL
V C
T
LOAD
CURRENT
LOAD CURRENT RISE TIME
1050plt1-1.0
ESR
=
37
4 6
8
.
m


Html Pages

1  2  3  4  5  6  7 


Fiches technique Télécharger

Go To PDF Page


Lien URL




Politique de confidentialité
ALLDATASHEET.FR
ALLDATASHEET vous a-t-il été utile ?  [ DONATE ] 

À propos de Alldatasheet   |   Publicité   |   Contactez-nous   |   Politique de confidentialité   |   Echange de liens   |   Fabricants
All Rights Reserved©Alldatasheet.com


Mirror Sites
English : Alldatasheet.com  |   English : Alldatasheet.net  |   Chinese : Alldatasheetcn.com  |   German : Alldatasheetde.com  |   Japanese : Alldatasheet.jp
Russian : Alldatasheetru.com  |   Korean : Alldatasheet.co.kr  |   Spanish : Alldatasheet.es  |   French : Alldatasheet.fr  |   Italian : Alldatasheetit.com
Portuguese : Alldatasheetpt.com  |   Polish : Alldatasheet.pl  |   Vietnamese : Alldatasheet.vn