Electronic Components Datasheet Search
  English  ▼

X  

Preview PDF HTML

LTC1876 Datasheet(PDF) 29 Page - Linear Technology

Part # LTC1876
Description  High Efficiency, 2-Phase, Dual Synchronous Step-Down Switching Controller and Step-Up Regulator
PDF  36 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  LINER [Linear Technology]
Direct Link  http://www.linear.com
Logo LINER - Linear Technology

LTC1876 Datasheet(HTML) 29 Page - Linear Technology

Back Button LTC1876 Datasheet HTML 25Page - Linear Technology LTC1876 Datasheet HTML 26Page - Linear Technology LTC1876 Datasheet HTML 27Page - Linear Technology LTC1876 Datasheet HTML 28Page - Linear Technology LTC1876 Datasheet HTML 29Page - Linear Technology LTC1876 Datasheet HTML 30Page - Linear Technology LTC1876 Datasheet HTML 31Page - Linear Technology LTC1876 Datasheet HTML 32Page - Linear Technology LTC1876 Datasheet HTML 33Page - Linear Technology Next Button
Zoom Inzoom in Zoom Outzoom out
 29 / 36 page
background image
LTC1876
29
1876fa
Choosing 1% resistors; R1 = 25.5k and R2 = 32.4k yields
an output voltage of 1.816V.
The power dissipation on the top side MOSFET can be
easily estimated. Choosing a Siliconix Si4412DY results
in; RDS(ON) = 0.042Ω, CRSS = 100pF. At maximum input
voltage with T(estimated) = 50
°C:
P
V
V
CC
V
A
pF
kHz
mW
MAIN =
() +°
°
[]
Ω
()+ () ( )( )(
)
=
18
22
5
1
0 005 50
25
0 042
1 7 22
5
100
300
220
2
2
.
(.
)(
–
)
..
A short-circuit to ground will result in a folded back
current of:
I
mV
ns
V
H
A
SC =
Ω
+
µ


=
25
001
1
2
200
22
33
32
.
()
.
.
with a typical value of RDS(ON) and δ = (0.005/°C)(20)
= 0.1. The resulting power dissipated in the bottom
MOSFET is:
P
VV
V
A
mW
SYNC =
() ( )
Ω
()
=
22
1 8
22
32
11 0042
434
2
–.
..
.
which is less than under full-load conditions.
CIN is chosen for an RMS current rating of at least 3A at
temperature assuming only this channel is on. COUT is
chosen with an ESR of 0.02
Ω for low output ripple. The
output ripple in continuous mode will be highest at the
maximum input voltage. The output voltage ripple due to
ESR is approximately:
VORIPPLE = RESR(∆IL) = 0.02Ω(1.67A) = 33mVP–P
Design Example for Auxiliary Regulator
Assume the requirements are VIN = 5V, VOUT = 12V and
IOUTMAX = 300mA. The duty cycle is given by:
Duty Cycle
V
V
IN
OUT
==
10 58
–.
Since the required output current is 300mA, the ripple
current of the inductor is calculated to be 0.57A.
Hence the required inductor is:
L
V
Duty Cycle
fI
IN
L
=
∆
(•
)
(•
)
With the boost regulator operating at 1.2MHz,
L = 4.24
µH
A 10
µH inductor is selected for the circuit for lower ripple
inductor current. Since the output current is only 300mA,
a 0.5A MBR0520 Schottky is selected. The completed
circuit along with its efficiency curve is shown in Figure 13
and Figure 14 respectively.
APPLICATIO S I FOR ATIO
Figure 13. Design Example Schematic
Figure 14. Efficiency Curve for Design Example
1876 F13
LTC1876
AUXVIN
VIN3
5V
VOUT3
12V
300mA
CIN3
2.2
µF
COUT3
4.7
µF
AUXSW
AUXSD AUXVFB
SGND
+
SHDN
R8
113k
R7
13.3k
C3*
10pF
L3
10
µH
C1: TAIYO YUDEN X5R LMK212BJ225MG
C2: TAIYO YUDEN X5R EMK316BJ475ML
D1: ON SEMICONDUCTOR MBR0520
L1: SUMIDA CR43-100
*OPTIONAL
D1
LOAD CURRENT (mA)
0
300
400
1876 F14
100
200
90
85
80
75
70
65
60
55
50
VIN = 3.3V
VIN = 5V



Html Pages

1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36


Datasheet Download

Go To PDF Page


Link URL



Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Contact us   |   Privacy Policy   |   Link to Datasheet    |   Link Exchange   |   Manufacturer List
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
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com