Moteur de recherche de fiches techniques de composants électroniques
  French  ▼
ALLDATASHEET.FR

X  

MAX8725ETI Fiches technique(PDF) 27 Page - Maxim Integrated Products

No de pièce MAX8725ETI
Description  Multichemistry Battery Charger with Automatic System Power Selector
Download  30 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Fabricant  MAXIM [Maxim Integrated Products]
Site Internet  https://www.maximintegrated.com/en.html
Logo MAXIM - Maxim Integrated Products

MAX8725ETI Fiches technique(HTML) 27 Page - Maxim Integrated Products

Back Button MAX8725ETI Datasheet HTML 22Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 23Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 24Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 25Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 26Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 27Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 28Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 29Page - Maxim Integrated Products MAX8725ETI Datasheet HTML 30Page - Maxim Integrated Products  
Zoom Inzoom in Zoom Outzoom out
 27 / 30 page
background image
Multichemistry Battery Chargers with Automatic
System Power Selector
______________________________________________________________________________________
27
Choose a low-side MOSFET that has the lowest possi-
ble on-resistance (RDS(ON)), comes in a moderate-
sized package, and is reasonably priced. Make sure
that the DLO gate driver can supply sufficient current to
support the gate charge and the current injected into
the parasitic gate-to-drain capacitor caused by the
high-side MOSFET turning on; otherwise, cross-con-
duction problems can occur.
The MAX1909/MAX8725 have an adaptive dead-time cir-
cuit that prevents the high-side and low-side MOSFETs
from conducting at the same time (see the MOSFET
Drivers section). Even with this protection, it is still possi-
ble for delays internal to the MOSFET to prevent one
MOSFET from turning off when the other is turned on.
Select devices that have low turn-off times. To be
conservative, make sure that P1(tDOFF(MAX)) -
N1(tDON(MIN)) < 40ns. Failure to do so may result in
efficiency-killing shoot-through currents. If delay mis-
match causes shoot-through currents, consider adding
extra capacitance from gate to source on N1 to slow
down its turn-on time.
MOSFET Power Dissipation
Worst-case conduction losses occur at the duty factor
extremes. For the high-side MOSFET, the worst-case
power dissipation (PD) due to resistance occurs at the
minimum supply voltage:
Generally, a small high-side MOSFET is desired to
reduce switching losses at high input voltages.
However, the RDS(ON) required to stay within package
power-dissipation limits often limits how small the
MOSFET can be. The optimum occurs when the switch-
ing (AC) losses equal the conduction (I2RDS(ON))
losses. High-side switching losses do not usually
become an issue until the input is greater than approxi-
mately 15V. Switching losses in the high-side MOSFET
can become an insidious heat problem when maximum
AC adapter voltages are applied, due to the squared
term in the CV2 f switching-loss equation. If the high-
side MOSFET that was chosen for adequate RDS(ON) at
low supply voltages becomes extraordinarily hot when
subjected to VDCIN(MAX), then choose a MOSFET with
lower losses. Calculating the power dissipation in P1
due to switching losses is difficult since it must allow for
difficult quantifying factors that influence the turn-on
and turn-off times. These factors include the internal
gate resistance, gate charge, threshold voltage, source
inductance, and PC board layout characteristics. The
following switching-loss calculation provides only a very
rough estimate and is no substitute for breadboard
evaluation, preferably including a verification using a
thermocouple mounted on P1:
where CRSS is the reverse transfer capacitance of P1,
and IGATE is the peak gate-drive source/sink current.
For the low-side MOSFET (N1), the worst-case power
dissipation always occurs at maximum input voltage:
Choose a Schottky diode (D1, Figure 2) with a forward
voltage low enough to prevent the N1 MOSFET body
diode from turning on during the dead time. As a gen-
eral rule, a diode with a DC current rating equal to 1/3rd
the load current is sufficient. This diode is optional and
can be removed if efficiency is not critical.
Inductor Selection
The charge current, ripple, and operating frequency
(off-time) determine the inductor characteristics.
Inductor L1 must have a saturation current rating of at
least the maximum charge current plus 1/2 of the ripple
current (∆IL):
ISAT = ICHG + (1/2) ∆IL
PD N
V
V
I
R
BATT
DCIN
LOAD
DS ON
()
()
11
2
2
=
 ×
PD P
Switching
VC
f
I
I
DCIN MAX
RSS
SW
LOAD
GATE
(_
)
()
1
2
2
=
××
×
PD P
V
V
I
R
BATT
DCIN
LOAD
DS ON
()
()
1
2
2
=
×
0
1.0
0.5
1.5
810 111213
914 15161718
VBATT (V)
VDCIN = 19V
VCTL = ICTL = LDO
3 CELLS
4 CELLS
Figure 11. Ripple Current vs. Battery Voltage (MAX1909)


Numéro de pièce similaire - MAX8725ETI

FabricantNo de pièceFiches techniqueDescription
logo
Maxim Integrated Produc...
MAX8725ETI MAXIM-MAX8725ETI Datasheet
420Kb / 31P
   Multichemistry Battery Chargers with Automatic System Power Selector
2015
MAX8725ETI++ MAXIM-MAX8725ETI+ Datasheet
420Kb / 31P
   Multichemistry Battery Chargers with Automatic System Power Selector
2015
More results

Description similaire - MAX8725ETI

FabricantNo de pièceFiches techniqueDescription
logo
Maxim Integrated Produc...
MAX1909 MAXIM-MAX1909_V01 Datasheet
420Kb / 31P
   Multichemistry Battery Chargers with Automatic System Power Selector
2015
logo
Texas Instruments
BQ24702 TI-BQ24702 Datasheet
521Kb / 32P
[Old version datasheet]   MULTICHEMISTRY BATTERY CHARGER CONTROLLER AND SYSTEM POWER SELECTOR
logo
Maxim Integrated Produc...
MAX846A MAXIM-MAX846A Datasheet
106Kb / 12P
   Cost-Saving Multichemistry Battery-Charger System
Rev 0; 9/96
logo
Analog Devices
DC2039A AD-DC2039A Datasheet
4Mb / 32P
   Multichemistry Buck Battery Charger with Digital Telemetry System
logo
Linear Technology
LTC4015 LINER-LTC4015_15 Datasheet
1Mb / 76P
   Multichemistry Buck Battery Charger Controller with Digital Telemetry System
LTC4015 LINER-LTC4015 Datasheet
1Mb / 76P
   Multichemistry Buck Battery Charger Controller with Digital Telemetry System
logo
Texas Instruments
BQ24702 TI1-BQ24702_16 Datasheet
886Kb / 37P
[Old version datasheet]   MULTICHEMISTRY BATTERY CHARGER CONTROLLER
logo
Maxim Integrated Produc...
MAX8713 MAXIM-MAX8713 Datasheet
1Mb / 25P
   Simplified Multichemistry SMBus Battery Charger
Rev 0; 11/04
logo
Intersil Corporation
ISL6256HRZ INTERSIL-ISL6256HRZ Datasheet
837Kb / 26P
   Highly Integrated Battery Charger with Automatic Power Source Selector for Notebook Computers
September 14, 2010
logo
Renesas Technology Corp
ISL6256 RENESAS-ISL6256 Datasheet
1Mb / 26P
   Highly Integrated Battery Charger with Automatic Power Source Selector for Notebook Computers
More results


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


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
Indian : Alldatasheet.in  |   Mexican : Alldatasheet.com.mx  |   British : Alldatasheet.co.uk  |   New Zealand : Alldatasheet.co.nz
Family Site : ic2ic.com  |   icmetro.com