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參數(shù)資料
| 型號(hào)： | MAX1879EUA |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類(lèi)： | 穩(wěn)壓器 |
| 英文描述： | Simple, Efficient, 1-Cell Li+ Pulse Charger |
| 中文描述： | BATTERY CHARGE CONTROLLER, PDSO8 |
| 封裝： | MICRO MAX PACKAGE-8 |
| 文件頁(yè)數(shù)： | 9/11頁(yè) |
| 文件大?。?/td> | 198K |
| 代理商： | MAX1879EUA |
from 4.2V, and/or a reverse-current-protection diode
can be added in line at the source.
If the input is shorted, the MAX1879 will not allow current
to flow from BATT back through IN to the source.
However, the body diode inherent in the enhancement-
mode FET would still allow the cell to discharge rapidly.
To prevent this, add a power Schottky diode between
the source and IN as in Figure 4.
Adjusting the Battery Regulation Voltage
A typical Li+ cell should be charged at a constant cur-
rent until it reaches a voltage of about 4.2V, then
charged at this voltage until the current decays below a
predetermined level. The MAX1879 provides a simple
way to reduce this maximum target voltage with a sin-
gle resistor between ADJ and GND. Internally, ADJ
connects to a precision 1.4V reference through a 10k
resistor. Leave ADJ open for a battery regulation volt-
age (V
BR
) of 4.2V; connect a 1% resistor from ADJ to
GND to form a voltage-divider for lower battery regula-
tion voltage (V
BR
′
)
.
Select the external value using:
10k
V
V
BR
A 1% tolerance resistor at ADJ degrades system accu-
racy by only a fraction of a percent. For example, an
R
ADJ
of 410k
±1% reduces the battery regulation volt-
age by 2.4% (V
BR
′
= 4.1V from equation above, and
(V
BR
′
- V
BR
) / V
BR
= (4.1 - 4.2) / 4.2 = -2.4%).
Therefore, the additional system error is simply the R
ADJ
tolerance multiplied by the percent change in the bat-
tery regulation voltage, or (1%)(2.4%) = 0.024%.
Selecting Minimum On-Time
The minimum pulse on-times can be selected by con-
necting TSEL as indicated in Table 2. A short pulse
time may be preferred to minimize voltage overshoot at
the battery and prevent pack overvoltage protection
circuitry from prematurely activating. A long minimum
on-time may be needed when using AC adapters with
high turn-on overshoot to allow charging current to set-
tle before the end of the pulse.
Selecting External Components
Power Supply
One reason the MAX1879 Li+ cell-charging solution is
so compact and simple is that the charging current is
set by the external power source, not by the MAX1879
charging circuit. The PMOS FET in this application cir-
cuit is either on or off, allowing the source to be directly
connected to the cell or completely disconnected.
Therefore, it is very important to choose a power supply
R
1
ADJ
BR
=
′
M
Simple, Efficient, 1-Cell Li+ Pulse Charger
_______________________________________________________________________________________
9
THERM
ADJ
0.001
μ
F
IN
CHG
GATE
PMOS FET
FAIRCHILD FDC638P
-4.5A, -20V
0.07
AT V
GS
= -2.5V
CURRENT-LIMITED
WALL CUBE
(800mA, 6V max)
BATT
TSEL*
10k
SINGLE
Li+
CELL
2.2
μ
F
*SEE TABLE 2 FOR TSEL POSITION AND ASSOCIATED TIMER SETTINGS.
MAX1879
NTC THERMISTOR
FENWAL
140-103LAG-RBI
(10k
AT 25
°
C)
THERM
IN
CHG
GATE
PMOS FET
FAIRCHILD FDC638P
-4.5A, -20V
0.07
AT V
GS
= -2.5V
SCHOTTKY DIODE
30V, 1A
ZETEX ZHCS1000
CURRENT-LIMITED
WALL CUBE
(800mA, 6V max)
BATT
TSEL*
R
410k
1%**
SINGLE
Li+
CELL
2.2
μ
F
0.001
μ
F
5mA
LED
*SEE TABLE 2 FOR TSEL POSITION AND ASSOCIATED TIMER SETTINGS.
** R
SETS BATTERY REGULATION VOLTAGE TO 4.10V; LEAVE OPEN
FOR 4.2V.
MAX1879
ADJ
Figure 1. Simple Application Circuit
Figure 2. Application Circuit Including LED and Thermistor
Table 2. TSEL Minimum On-Time Settings
TSEL
CONNECTION
BATT
ADJ
GND
MINIMUM ON-TIME IN TOP-OFF
(ms)
34
69
137
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| MAX1879EUA+ | 功能描述:電池管理 1-Cell Li+ Pulse Charger RoHS:否 制造商:Texas Instruments 電池類(lèi)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(lèi)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(lèi)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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