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| 型号： | MAX1879EUA+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/11页 |
| 文件大小： | 0K |
| 描述： | IC CHARGER LI+ PULSE 8UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 功能： | 充电管理 |
| 电池化学： | 锂离子（Li-Ion） |
| 电源电压： | 4.4 V ~ 22 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 8-TSSOP，8-MSOP（0.118"，3.00mm 宽） |
| 供应商设备封装： | 8-uMAX |
| 包装： | 带卷 (TR) |
Simple, Efficient, 1-Cell Li+ Pulse Charger
R ADJ =
V BR
V BR ′
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 ?
? 1
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
Table 2. TSEL Minimum On-Time Settings
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%).
TSEL
CONNECTION
BATT
ADJ
GND
MINIMUM ON-TIME IN TOP-OFF
(ms)
34
69
137
CURRENT-LIMITED
WALL CUBE
(800mA, 6V max)
PMOS FET
FAIRCHILD FDC638P
-4.5A, -20V
0.07 ? AT V GS = -2.5V
CURRENT-LIMITED SCHOTTKY DIODE
WALL CUBE 30V, 1A
(800mA, 6V max) ZETEX ZHCS1000
PMOS FET
FAIRCHILD FDC638P
-4.5A, -20V
0.07 ? AT V GS = -2.5V
GATE
GATE
IN
MAX1879
BATT
5mA
LED
IN
MAX1879
BATT
SINGLE
CHG
TSEL*
Li+
CHG
0.001 μ F
ADJ
THERM
10k ?
TSEL*
2.2 μ F
SINGLE
Li+
CELL
0.001 μ F
R ADJ
410k ?
1%**
ADJ THERM 2.2 μ F
NTC THERMISTOR
FENWAL
140-103LAG-RBI
(10k ? AT 25 ° C)
CELL
*SEE TABLE 2 FOR TSEL POSITION AND ASSOCIATED TIMER SETTINGS.
*SEE TABLE 2 FOR TSEL POSITION AND ASSOCIATED TIMER SETTINGS.
Figure 1. Simple Application Circuit
** R ADJ SETS BATTERY REGULATION VOLTAGE TO 4.10V; LEAVE OPEN
FOR 4.2V.
Figure 2. Application Circuit Including LED and Thermistor
_______________________________________________________________________________________
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相关代理商/技术参数 |
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| MAX1879EVKIT | 制造商:Maxim Integrated Products 功能描述:SMALLEST, SIMPLE 1-CELL LI- PULSE CHARGER WIT - Bulk |
| MAX187ACPA | 功能描述:模数转换器 - ADC Integrated Circuits (ICs) RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX187ACPA+ | 功能描述:模数转换器 - ADC 12-Bit 75ksps 5.25V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX187ACWE | 功能描述:模数转换器 - ADC Integrated Circuits (ICs) RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX187ACWE+ | 功能描述:模数转换器 - ADC 12-Bit 75ksps 5.25V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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