Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

TK65025MBX Datasheet(PDF) 8 Page - TOKO, Inc

Part # TK65025MBX
Description  STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  TOKO [TOKO, Inc]
Direct Link  http://www.toko.com
Logo TOKO - TOKO, Inc

TK65025MBX Datasheet(HTML) 8 Page - TOKO, Inc

Back Button TK65025MBX Datasheet HTML 4Page - TOKO, Inc TK65025MBX Datasheet HTML 5Page - TOKO, Inc TK65025MBX Datasheet HTML 6Page - TOKO, Inc TK65025MBX Datasheet HTML 7Page - TOKO, Inc TK65025MBX Datasheet HTML 8Page - TOKO, Inc TK65025MBX Datasheet HTML 9Page - TOKO, Inc TK65025MBX Datasheet HTML 10Page - TOKO, Inc TK65025MBX Datasheet HTML 11Page - TOKO, Inc TK65025MBX Datasheet HTML 12Page - TOKO, Inc  
Zoom Inzoom in Zoom Outzoom out
 8 / 12 page
background image
Page 8
February, 1997 Toko, Inc.
TK65025
series (surface mount); Matsuo 267 series (surface mount);
Sanyo OS-CON series (miniature through hold).
I
O =
V
BB
2
D
D
2 f L


1-
D
2 f L
R
S + R L + R SW
()


2
V
O + R OF I O(TGT) +
D
2 f L
V
BBR U
() + V
F − V BB
1-
D
2 f L
R
S + R L
()


f C
S V BB
2 + V
O + V F
()2 + V
O + V F − V BB
()2
[]
2V
O + V F
()
Higher-Order Design Equation
The equation above was developed as a closed form
approximation for the design variable that required the
least approximation to allow a closed form. In this case,
that variable was “I
O” (e.g., as opposed to “L”).
The approximations made in the equation development
have the primary consequence that error is introduced as
resistive losses become relatively large. As it is normally
a practical design goal to ensure that resistive losses will
be relatively small, this seems acceptable. The variables
used are:
I
O
Output current
capability
I
O(TGT)
Targeted output current capability
V
O
Output voltage
V
F
Diode forward voltage
V
BB
Battery voltage, unloaded
D
Oscillating duty ratio of main switch
f
Oscillator frequency
L
Inductance value
R
S
Source resistance (battery + filter)
R
L
Inductor winding resistance
R
SW
Switch on-state resistance
R
OF
Output filter resistance
R
U
ESR of upstream output capacitor
C
S
Snubber capacitance
Deriving a design solution with this equation is neces-
sarily an iterative process. Use worst case tolerances as
described for inductor selection, plugging in different val-
ues for “L” to approximately achieve an “I
O” equal to the
targeted value. Then, fine tune the parasitic values as
needed and, if necessary, readjust “L” again and reiterate
the process.
DUAL-CELL APPLICATION
There are special considerations involved in designing
a converter with the TK65025 for use with two battery cells.
With two battery cells the TK65025 can provide substan-
tially more output current than a single cell input for the
same efficiency.
The concern is the possibility of saturating the inductor.
For a single cell input it was only necessary to choose the
current capability in accordance with the maximum peak
current that could be calculated using Eq. (4). For a two
cell input the peak current is not so readily determined
because the inductor can go into
continuous mode. When
this happens, the increase of current during the on-time
remains more-or-less the same (i.e., approximately equal
to the peak current as calculated using Eq. (4)), but the
inductor current doesn’t start from zero. It starts from
where it had decayed to during the previous off-time.
There is no deadtime associated with a single switching
period when in continuous mode because the inductor
current never decays to zero within one cycle.
The cause for continuous mode operation is readily
seen by noting that the rate of current increase in the
inductor during the on-time is faster than the rate of decay
during the off-time. The reason for that is because there
is more voltage applied across the switch during the
on-time (two battery cells) than during the off-time (3 volts
plus a diode drop minus two battery cells). That situation,
in conjunction with a switch duty ratio of about 50%, implies
that the current can’t fall as much as it can rise during a
cycle. So when a switching cycle begins with zero current
in the inductor, it ends with current still flowing.
Continuous mode operation implies that the inductor
value no longer restricts the output current capability. With
discontinuous mode operation, it was necessary to choose
a lower inductor value to achieve a higher output current
rating. (Eq. (6) specifically shows “I
O” as a function of “L”.)
This also implied higher ripple current from the battery. In
continuous mode operation, one can choose a larger
inductor value intentionally if it is desirable to minimize
ripple current. The catch is that high inductance and high
current rating together generally imply larger inductor size.
But generally this unrestricted inductor value allows more
freedom in the converter design.
The dual cell input and the continuous current rating
imply that the peak current in the inductor will be at least
twice as high as it would for a single cell input using the
same inductor value.
The Toko D73 and D75 series
inductors are particularly suited for the higher output
current capability of the dual cell configuration.
For operation at a fixed maximum load, the inductor can
be kept free of saturation by choosing its peak current
(6)


Similar Part No. - TK65025MBX

ManufacturerPart #DatasheetDescription
logo
TOKO, Inc
TK65020 TOKO-TK65020 Datasheet
94Kb / 14P
   STEP-UP VOLTAGE CONVERTER
TK65020MTL TOKO-TK65020MTL Datasheet
94Kb / 14P
   STEP-UP VOLTAGE CONVERTER
TK65020MTL/20M TOKO-TK65020MTL/20M Datasheet
94Kb / 14P
   STEP-UP VOLTAGE CONVERTER
More results

Similar Description - TK65025MBX

ManufacturerPart #DatasheetDescription
logo
TOKO, Inc
TK65015 TOKO-TK65015 Datasheet
116Kb / 8P
   STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR
TK652XX TOKO-TK652XX Datasheet
141Kb / 20P
   STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR
TK651XX TOKO-TK651XX Datasheet
138Kb / 20P
   STEP-UP VOLTAGE CONVERTER WITH VOLTAGE MONITOR
TK65020 TOKO-TK65020 Datasheet
94Kb / 14P
   STEP-UP VOLTAGE CONVERTER
logo
Linear Technology
LTC3108-1 LINER-LTC3108-1_12 Datasheet
258Kb / 24P
   Ultralow Voltage Step-Up Converter
LTC3108 LINER-LTC3108_12 Datasheet
237Kb / 22P
   Ultralow Voltage Step-Up Converter
logo
TOKO, Inc
TK653XX TOKO-TK653XX Datasheet
29Kb / 2P
   HIGH CURRENT STEP-UP CONVERTER WITH BATTERY MONITOR
logo
Monolithic Power System...
MP3430 MPS-MP3430 Datasheet
1,012Kb / 15P
   90V Step-Up Converter with APD Current Monitor
logo
Micon Design Technology...
MDT763320 MDTIC-MDT763320 Datasheet
149Kb / 5P
   Step-up DC/DC Converter with Voltage Detector
MDT763020 MDTIC-MDT763020 Datasheet
127Kb / 5P
   Step-up DC/DC Converter with Voltage Detector
More results


Html Pages

1 2 3 4 5 6 7 8 9 10 11 12


Datasheet Download

Go To PDF Page


Link URL




Privacy Policy
ALLDATASHEET.COM
Does ALLDATASHEET help your business so far?  [ DONATE ] 

About Alldatasheet   |   Advertisement   |   Datasheet Upload   |   Contact us   |   Privacy Policy   |   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