Electronic Components Datasheet Search
  English  ▼
ALLDATASHEET.COM

X  

LTC4057 Datasheet(PDF) 7 Page - Linear Technology

Part # LTC4057
Description  Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
Download  12 Pages
Scroll/Zoom Zoom In 100%  Zoom Out
Manufacturer  LINER [Linear Technology]
Direct Link  http://www.linear.com
Logo LINER - Linear Technology

LTC4057 Datasheet(HTML) 7 Page - Linear Technology

Back Button LTC4057 Datasheet HTML 3Page - Linear Technology LTC4057 Datasheet HTML 4Page - Linear Technology LTC4057 Datasheet HTML 5Page - Linear Technology LTC4057 Datasheet HTML 6Page - Linear Technology LTC4057 Datasheet HTML 7Page - Linear Technology LTC4057 Datasheet HTML 8Page - Linear Technology LTC4057 Datasheet HTML 9Page - Linear Technology LTC4057 Datasheet HTML 10Page - Linear Technology LTC4057 Datasheet HTML 11Page - Linear Technology Next Button
Zoom Inzoom in Zoom Outzoom out
 7 / 12 page
background image
LTC4057-4.2
7
4057f
Stability Considerations
The constant-voltage mode feedback loop is stable with-
out an output capacitor provided a battery is connected to
the charge output. When an output capacitor is used,
especially high value low ESR ceramic types, it is recom-
mended that a 1
Ω resistor be placed in series with the
capacitor to stabilize the voltage loop. The loop stability is
determined by the bypass capacitor as well as the effective
series resistance of the battery.
When the battery is disconnected and the LTC4057 is still
powered, the voltage regulation loop should be compen-
sated by placing a capacitor greater than 1
µF from the BAT
pin to ground with a 1
Ω to 2Ω resistor in series with this
capacitor. Alternatively, powering down the LTC4057 or
placing it into shutdown mode when the battery is discon-
nected avoids this problem.
In constant-current mode, the PROG pin is in the feedback
loop, not the battery. The constant-current mode stability
is affected by the impedance at the PROG pin. With no
additional capacitance on the PROG pin, the charger is
stable with program resistor values as high as 20k. How-
ever, additional capacitance on this node reduces the
maximum allowed program resistor value. The pole fre-
quency at the PROG pin should be kept above 100kHz.
Therefore, if the PROG pin is loaded with a capacitance,
CPROG, the following equation can be used to calculate the
maximum resistance value for RPROG:
R
C
PROG
PROG
1
2105
π ••
Average, rather than instantaneous, battery current may
be of interest to the user. For example, if a switching power
supply operating in low-current mode is connected in
parallel with the battery, the average current being pulled
out of the BAT pin is typically of more interest than the
instantaneous current pulses. In such a case, a simple RC
filter can be used on the PROG pin to measure the average
battery current as shown in Figure 1. A 10k resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
APPLICATIO S I FOR ATIO
Power Dissipation
The conditions that cause the LTC4057 to reduce charge
current through thermal feedback can be approximated by
considering the power dissipated in the IC. Nearly all of
this power dissipation is generated by the internal MOSFET.
This is calculated to be approximately:
PD = (VCC – VBAT) • IBAT
where PD is the power dissipated, VCC is the input supply
voltage, VBAT is the battery voltage, and IBAT is the charge
current. The approximate ambient temperature at which
the thermal feedback begins to protect the IC is:
TA = 120°C – PDθJA
TA = 120°C – (VCC – VBAT) • IBAT • θJA
Example: An LTC4057 operating from a 4.5V USB supply
is programmed to supply 600mA full-scale current to a
discharged Li-Ion battery with a voltage of 3.7V. Assuming
θJA is 150°C/W (see Board Layout Considerations), the
ambient temperature at which the LTC4057 will begin to
reduce the charge current is approximately:
TA = 120°C – (4.5V – 3.7V) • (600mA) • 150°C/W
TA = 120°C – 0.48W • 150°C/W = 120°C – 72°C
TA = 48°C
The LTC4057 can be used above 48
°C ambient, but the
charge current will be reduced from 600mA. The approxi-
mate current at a given ambient temperature can be
approximated by:
I
CT
VV
BAT
A
CC
BAT
JA
=
°
120
()•
θ
LTC4057-4.2
PROG
GND
10k
RPROG
CFILTER
CHARGE CURRENT
MONITOR CIRCUITRY
4057 F01
Figure 1. Isolating Capacitive Load on PROG Pin and Filtering


Similar Part No. - LTC4057

ManufacturerPart #DatasheetDescription
logo
Linear Integrated Syste...
LTC4057 LINEAR-LTC4057 Datasheet
195Kb / 18P
   Standalone 250mA Li-Ion Battery Charger in 2 횞 2 DFN
logo
Linear Technology
LTC4057 LINER-LTC4057 Datasheet
196Kb / 16P
   Standalone 750mA Li-Ion Battery Charger in 2 x 2 DFN
LTC4057 LINER-LTC4057 Datasheet
196Kb / 16P
   Standalone 750mA Li-Ion Battery Charger in 2 x 2 DFN
LTC4057 LINER-LTC4057 Datasheet
290Kb / 24P
   USB Power Manager with Ideal Diode Controller and Li-Ion Charger
LTC4057-4.2 LINER-LTC4057-4.2 Datasheet
154Kb / 12P
   Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
More results

Similar Description - LTC4057

ManufacturerPart #DatasheetDescription
logo
Linear Technology
LTC4057-4.2 LINER-LTC4057-4.2_15 Datasheet
154Kb / 12P
   Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
LTC4054X-4.2 LINER-LTC4054X-4.2_15 Datasheet
197Kb / 16P
   Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
LTC4054-4.2 LINER-LTC4054-4.2_15 Datasheet
197Kb / 16P
   Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
LTC4054X LINER-LTC4054X Datasheet
188Kb / 16P
   Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
logo
Eutech Microelectronics...
EUP8054 EUTECH-EUP8054 Datasheet
431Kb / 17P
   Standalone Linear Li-Ion Battery Charger With Thermal Regulation in ThinSOT
logo
SHOUDING Shouding Semic...
SD4054 SHOUDING-SD4054 Datasheet
609Kb / 14P
   600mA Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
SD8055 SHOUDING-SD8055 Datasheet
611Kb / 14P
   600mA Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
logo
Lowpower Semiconductor ...
LP4060A POWER-LP4060A Datasheet
794Kb / 13P
   800mA Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
LP4062 POWER-LP4062 Datasheet
596Kb / 13P
   600mA Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
logo
List of Unclassifed Man...
LP4054 ETC-LP4054 Datasheet
561Kb / 14P
   600mA Standalone Linear Li-Ion Battery Charger with Thermal Regulation in ThinSOT
V1.0
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