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參數(shù)資料
| 型號(hào)： | MAX1879 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Simple, Efficient, 1-Cell Li+ Pulse Charger |
| 中文描述： | 簡(jiǎn)單、高效率、1節(jié)Li+電池脈沖充電器 |
| 文件頁(yè)數(shù)： | 10/11頁(yè) |
| 文件大?。?/td> | 198K |
| 代理商： | MAX1879 |
M
with current limiting. In most applications, this will be a
small
“
wall cube
”
switching converter with an output
voltage limit of about 5V or 6V, which is specified as
“
current-limited
”
or
“
constant current.
”
PMOS Switch
The PMOS FET switches the current-limited source on
and off. Because of the intentionally slow switching
times and limited slew rate, the MAX1879 is not particu-
lar about the power FET it drives. Specifications to con-
sider when choosing an appropriate FET are the
minimum drain-source breakdown voltage, the minimum
turn-on threshold voltage (V
GS
), and current-handling
and power-dissipation qualities. The minimum break-
down voltage (BV
DS
) must exceed the open-circuit volt-
age of the wall cube by at least 25%. Note that this
open-circuit voltage may be twice as high as the specified
output voltage, depending on the AC adapter type.
Thermistor
The intent of THERM is to inhibit fast-charging the cell
when it is too cold or too hot (+2.5
°
C
≤
T
OK
≤
47.5
°
C),
using an external thermistor. THERM time multiplexes
two sense currents to test for both hot and cold qualifi-
cation. The thermistor should be 10k
at +25
°
C and
have a negative temperature coefficient (NTC); the
THERM pin expects 3.97k
at +47.5
°
C and 28.7k
at
+2.5
°
C. Connect the thermistor between THERM and
GND. If no temperature qualification is desired, replace
the thermistor with a 10k
resistor. Thermistors by
Philips (22322-640-63103), Cornerstone Sensors
(T101D103-CA), and Fenwal Electronics (140-103LAG-
RB1) work well.
Bypass Capacitors
Bypass the ADJ pin with a 2000pF ceramic capacitor.
Bypass BATT with a capacitor with a value of at least
1.5μF per amp of charge current. The MAX1879 has a
built-in protection feature that prevents BATT from rising
above 5.5V. The device recognizes a rapid rise at BATT,
indicating that the cell is being removed with the FET on.
A capacitor from BATT to GND that
’
s too small does not
give the MAX1879 adequate time to shut off the FET.
BATT may then rise above 6V (towards the open-circuit
source voltage), violating the absolute maximum rating
and damaging the device.
In applications where the cell is removable, very large
capacitance values make it increasingly difficult to iden-
tify momentary cell removal events and may increase
transient currents when the cell is replaced. Therefore,
values in excess of 100μF should be avoided in those
cases. For best system performance, at least 0.47μF of
the total capacitance should be low-ESR ceramic.
Layout Guidelines
The MAX1879 controls the GATE slew rate. The layout is
not as sensitive to noise as a high-frequency switching
regulator. In addition, since the cell voltage is sensed
both during and between high-current pulses, the sys-
tem is insensitive to ground drops. However, Maxim rec-
ommends establishing good grounding areas and large
traces for high-current paths.
Chip Information
TRANSISTOR COUNT: 4692
SUBSTRATE CONNECTED TO GND
Simple, Efficient, 1-Cell Li+ Pulse Charger
10
______________________________________________________________________________________
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1879EUA | 功能描述:電池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX1879EUA+ | 功能描述:電池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX1879EUA+T | 功能描述:電池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX1879EUA-T | 功能描述:電池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 電池類型:Li-Ion 輸出電壓:5 V 輸出電流:4.5 A 工作電源電壓:3.9 V to 17 V 最大工作溫度:+ 85 C 最小工作溫度:- 40 C 封裝 / 箱體:VQFN-24 封裝:Reel |
| MAX1879EVKIT | 制造商:Maxim Integrated Products 功能描述:SMALLEST, SIMPLE 1-CELL LI- PULSE CHARGER WIT - Bulk |
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