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参数资料
| 型号： | LTC4069EDC-4.4#PBF |
| 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： | 197K |
| 代理商： | LTC4069EDC-4.4#PBF |
LTC4069-4.4
13
406944fa
APPLICATIONS INFORMATION
Power Dissipation
The conditions that cause the LTC4069-4.4 to reduce charge
current through thermal feedback can be approximated
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
approximately:
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
Using the previous example with an ambient temperature
of 73°C, the charge current will be reduced to
approximately:
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 applications
do not need to be designed for worst-case thermal
conditions since the IC will automatically limit power
dissipation when the junction temperature reaches
approximately 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
thermal 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 capacitors, 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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