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| 型号： | MAX8971EWP+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 17/39页 |
| 文件大小： | 0K |
| 描述： | IC DCDC CHRGR LI+ 1CELL 20WLP |
| 标准包装： | 2,500 |
| 功能： | 充电管理，过压/欠压保护 |
| 电池化学： | 锂离子（Li-Ion）、锂聚合物（Li-Pol） |
| 电源电压： | 4 V ~ 7.5 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | * |
| 封装/外壳： | * |
| 供应商设备封装： | * |
| 包装： | * |
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MAX8971
Industry's Smallest 1.55A
1-Cell Li+ DC-DC Charger
10k I at R TB resistor, the charger enters a temperature
suspend state when the thermistor resistance falls below
3.97k I (too hot) or rises above 28.7k I (too cold). This
corresponds to the 0 N C to +50 N C range when using a
10k I NTC thermistor with a beta of 3500. The general
relation of thermistor resistance to temperature is defined
by the following equation:
R T = R 25 x e{ A ((1/(T+273)) x (1/298))}
where:
R T = the resistance in I of the thermistor at tempera-
ture T in celsius
R 25 = the resistance in I of the thermistor at +25 N C
Note that since AVL is active whenever valid input power
is connected at DC, thermistor bias current flows at all
times. Using a 10k I thermistor and a 10k I pullup to
AVL, results in an additional 250 F A load. This load can
be reduced to 25 F A by instead using a 100k I thermistor
and 100k I pullup resistor.
Thermal Foldback
Thermal foldback maximizes the battery charge current
while regulating the IC's junction temperature. When
the die temperature exceeds T REG , a thermal limiting
circuit reduces the battery charge-current target until the
charge current reaches 10% of the fast-charge current
setting. The charger maintains 10% of the fast-charge
A =
the material constant of the thermistor, which typi-
cally ranges from 3000k to 5000k
current until the die temperature reaches T SHDN . Please
note that the IC is rated for a maximum ambient tem-
T = the temperature of the thermistor in N C
Some designs might prefer other thermistor temperature
limits. Threshold adjustment can be accommodated by
changing R TB , connecting a resistor in series and/or in
parallel with the thermistor, or using a thermistor with
different A . For example, a +45 N C hot threshold and 0 N C
cold threshold can be realized by using a thermistor with
a A to 4250, and connecting 120k I in parallel. Since the
thermistor resistance near 0 N C is much higher than it is
near +50 N C, a large parallel resistance lowers the cold
threshold, while only slightly lowering the hot threshold.
Conversely, a small series resistance raises the cold
threshold, while only slightly raising the hot threshold.
Raising R TB, lowers both the hot and cold threshold,
while lowering R TB raises both thresholds.
perature of +85 N C. Furthermore, although the maximum
die temperature of the MAX8971 is +150 N C, it is common
industry practice to design systems in such a way that
the die temperature never exceeds +125 N C. Limiting the
maximum die temperature to +125 N C extends long-term
reliability.
Charger States
The IC utilizes several charging states to safely and
quickly charge batteries as shown in Figure 3.
Figure 2 shows an exaggerated view of a Li+/Li-Poly
battery progressing through the following charge states
when the die and battery are close to room temperature:
dead battery ? prequalification ? fast charge ? top-off
? done.
Table 1. Trip Temperatures for Different Thermistors
THERMISTOR
T EMPERATUR E
R THM at T A =+25 ° C
Thermistor Beta ( AI )
RTB ( I )
RTP ( I )
RTS ( I )
Resistance at T1_n15
( I )
Resistance at T1_0( I )
10,000
3380
10,000
Open
Short
61,788
29,308
10,000
3940
10,000
Open
Short
61,788
29,308
10,000
3940
10,000
301,000
499
77,248
31,971
47,000
4050
47,000
Open
Short
290,410
137,750
47,000
4050
47,000
1,200,000
2,400
380,716
153,211
100,000
4250
100,000
Open
Short
617,913
293,090
100,000
4250
100,000
1,800,000
6,800
934,027
343,283
Maxim Integrated
17
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相关代理商/技术参数 |
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|---|---|
| MAX8971QEWP+T | 功能描述:电池管理 Switch-Mode Li+ Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX8973AEWI+ | 制造商:Maxim Integrated Products 功能描述:HIGH CURRENT, MULTI-PHASE DC/DC STEP-DOWN CONVERTER - Rail/Tube |
| MAX8973AEWI+T | 制造商:Maxim Integrated Products 功能描述:HIGH CURRENT, MULTI-PHASE DC/DC STEP-DOWN CONVERTER - Tape and Reel |
| MAX8982AEWO+T | 制造商:Maxim Integrated Products 功能描述:POWER MANAGEMENT IC FOR ICERA E400/E450 PLATFORM-MINI CARD - Tape and Reel |
| MAX8982EWO+T | 功能描述:PMIC 解决方案 PMIC for ICERA E400/E450 Platform RoHS:否 制造商:Texas Instruments 安装风格:SMD/SMT 封装 / 箱体:QFN-24 封装:Reel |
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