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参数资料
| 型号： | LTC4069EDC-4.4#TRMPBF |
| 厂商： | LINEAR TECHNOLOGY CORP |
| 元件分类： | 电源管理 |
| 英文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO6 |
| 封装： | 2 X 2 MM, LEAD FREE, PLASTIC, MO-229WCCD-2, DFN-6 |
| 文件页数： | 5/16页 |
| 文件大小： | 192K |
| 代理商： | LTC4069EDC-4.4#TRMPBF |
13
LTC4069-4.4
406944f
filter can be used on the PROG pin to measure the average
battery current as shown in Figure 5. A 10K resistor has
been added between the PROG pin and the filter capacitor
to ensure stability.
Power Dissipation
The conditions that cause the LTC4069-4.4 to reduce
charge current through thermal feedback can be approxi-
mated by considering the power dissipated in the IC. For
high charge currents, the LTC4069-4.4 power dissipation
is 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. It is not necessary to perform any worst-case
power dissipation scenarios because the LTC4069-4.4
will automatically reduce the charge current to maintain
the die temperature at approximately 115
°C. However, the
approximate ambient temperature at which the thermal
feedback begins to protect the IC is:
TA = 115°C – PD θJA
TA = 115°C – (VCC – VBAT) IBAT θJA
Example: Consider an LTC4069-4.4 operating from a 5V
wall adapter providing 750mA to a 3.6V Li-Ion battery. The
ambient temperature above which the LTC4069-4.4 will
begin to reduce the 750mA charge current is approxi-
mately:
TA = 115°C – (5V – 3.6V) (750mA) 60°C/W
TA = 115°C – (1.05W 60°C/W) = 115°C – 63°C
TA = 52°C
The LTC4069-4.4 can be used above 70
°C, but the charge
current will be reduced from 750mA. The approximate
current at a given ambient temperature can be calculated:
I
CT
VV
BAT
A
CC
BAT
JA
=
°
()
115
–
θ
APPLICATIO S I FOR ATIO
WU
UU
Using the previous example with an ambient temperature
of 73
°C, the charge current will be reduced to approxi-
mately:
I
CC
VV
C W
C
CA
mA
BAT =
°°
() °
=
°
=
115
73
53 6
60
42
84
500
–
–.
/
Furthermore, the voltage at the PROG pin will change
proportionally with the charge current as discussed in the
Programming Charge Current section.
It is important to remember that LTC4069-4.4 applica-
tions do not need to be designed for worst-case thermal
conditions since the IC will automatically limit power
dissipation when the junction temperature reaches ap-
proximately 115
°C.
Board Layout Considerations
In order to deliver maximum charge current under all
conditions, it is critical that the exposed metal pad on the
backside of the LTC4069-4.4 package is soldered to the PC
board copper and extending out to relatively large copper
areas or internal copper layers connected using vias.
Correctly soldered to a 2500mm2 double-sided 1 oz.
copper board the LTC4069-4.4 has a thermal resistance of
approximately 60
°C/W. Failure to make thermal contact
between the Exposed Pad on the backside of the package
and the copper board will result in thermal resistances far
greater than 60
°C/W. As an example, a correctly soldered
LTC4069-4.4 can deliver over 750mA to a battery from a
5V supply at room temperature. Without a backside ther-
mal connection, this number could drop to less than
500mA.
VCC Bypass Capacitor
Many types of capacitors can be used for input bypassing;
however, caution must be exercised when using multi-
layer ceramic capacitors. Because of the self-resonant and
high Q characteristics of some types of ceramic capaci-
tors, high voltage transients can be generated under some
start-up conditions, such as connecting the charger input
to a live power source. For more information, refer to
Application Note 88.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| LTC4069EDC-PBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Standalone 750mA Li-Ion Battery Charger in 2 × 2 DFN with NTC Thermistor Input |
| LTC4069EDC-TRPBF | 制造商:LINER 制造商全称:Linear Technology 功能描述:Standalone 750mA Li-Ion Battery Charger in 2 × 2 DFN with NTC Thermistor Input |
| LTC4070 | 制造商:LINEAR 制造商全称:LINEAR 功能描述:Ultralow Voltage Step-Up Converter and Power Manager |
| LTC4070EDDB | 制造商:LINER 制造商全称:Linear Technology 功能描述:Li-Ion/Polymer Shunt Battery Charger System |
| LTC4070EDDB#PBF | 制造商:Linear Technology 功能描述:Battery Charger Li-Ion/Li-Pol 50mA 4.2V 10-Pin DFN EP Bulk 制造商:Linear Technology 功能描述:IC BATTERY CHARGER 50mA DFN-8 制造商:Linear Technology 功能描述:IC, BATTERY CHARGER, 50mA, DFN-8 制造商:Linear Technology 功能描述:IC, BATTERY CHARGER, 50mA, DFN-8; Battery Type:Li-Ion, Li-Polymer; Battery Charge Voltage:4.2V; Charge Current Max:50mA; Battery IC Case Style:DFN; No. of Pins:8; No. of Series Cells:1; Operating Temperature Min:-40C ;RoHS Compliant: Yes |
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