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| 型号： | MAX1757EAI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 15/17页 |
| 文件大小： | 0K |
| 描述： | IC BATTERY CHRG LI+ 28-SSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,000 |
| 功能： | 充电管理 |
| 电池化学： | 锂离子（Li-Ion）、锂聚合物（Li-Pol） |
| 电源电压： | 6 V ~ 14 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-SSOP（0.209"，5.30mm 宽） |
| 供应商设备封装： | 28-SSOP |
| 包装： | 带卷 (TR) |
MAX1757
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 14V Switch
CELL is the programming input for selecting cell count
N. Table 2 shows how CELL is connected to charge 1,
2, or 3 cells.
where f OSC is the switching frequency (300kHz).
The peak inductor current is given by:
I PEAK = I ISETOUT ? 1 +
?
Setting the Charging Current Limit
A resistor-divider from REF to GND sets the voltage at
ISETOUT (V ISETOUT ). This determines the charging cur-
?
?
LIR ?
2 ?
I CHG = 1 . 5 A ?
? V ISETOUT ?
?
?
?
rent during the current-regulation (fast-charge) mode.
The full-scale charging current is 1.5A.
The charging current (I CHG ) is, therefore:
V REF
Connect ISETOUT to REF to get the full-scale current
limit.
Setting the Input Current Limit
Capacitor Selection
The input capacitor shunts the switching current from
the charger input and prevents that current from circu-
lating through the source, typically an AC wall cube.
Thus, the input capacitor must be able to handle the
input RMS current. Typically, at high charging currents,
the converter will operate in continuous conduction (the
inductor current does not go to 0). In this case, the
RMS current of the input capacitor may be approximat-
ed by the equation:
A resistor-divider from REF to GND sets the voltage at
ISEVTIN (V ISETIN ). This sets the maximum source cur-
rent allowed at any time during charging. The source
I CIN ? I CHG
D ? D 2
I IN FSS ? ISETIN ?
= I
current I FSS is set by the current-sense resistor
R SOURCE between CSSP and CSSN. The full-scale
source current is I FSS = 0.1V / R1 (Figure 1).
The input current limit (I IN ) is therefore:
? V ?
? V REF ?
Connect ISETIN to REF to get the full-scale input cur-
rent limit. Short CSSP and CSSN if the input source cur-
rent limit is not used.
In choosing the current-sense resistor, it should be noted
that the drop across this resistor adds to the power loss
and thus reduces efficiency. However, too low a resistor
value may degrade input current-limit accuracy.
Inductor Selection
The inductor value may be changed for more or less
ripple current. The higher the inductance, the lower the
ripple current will be; however, as the physical size is
kept the same, typically, higher inductance will result in
higher series resistance and lower saturation current. A
good tradeoff is to choose the inductor so that the rip-
ple current is approximately 30% to 50% of the DC
average charging current. The ratio of ripple current to
DC charging current (LIR) can be used to calculate the
optimal inductor value:
where:
I CIN is the input capacitor RMS current.
D is the PWM converter duty ratio
(typically V BATT / V DCIN ).
I CHG is the battery charging current.
The maximum RMS input current occurs at 50% duty
cycle; thus, the worst-case input ripple current is 0.5 ?
I CHG . If the input-to-output voltage ratio is such that the
PWM controller will never work at 50% duty cycle, then
the worst-case capacitor current will occur where the
duty cycle is nearest 50%.
The input capacitor impedance is critical to preventing
AC currents from flowing back into the wall cube. This
requirement varies depending on the wall cube imped-
ance and the requirements of any conducted or radiat-
ed EMI specifications that must be met. Aluminum
electrolytic capacitors are generally the cheapest, but
usually are a poor choice for portable devices due to
their large size and poor equivalent series resistance
(ESR). Tantalum capacitors are better in most cases, as
are high-value ceramic capacitors. For equivalent size
and voltage rating, tantalum capacitors will have higher
capacitance, but also higher ESR than ceramic capaci-
tors. This makes it more critical to consider RMS cur-
rent and power dissipation ratings when using tantalum
capacitors.
V BATT ( V DCIN ( ) ? V BATT )
V DCIN ( MAX ) x f OSC CHG x LIR
L =
MAX
x I
The output filter capacitor is used to absorb the induc-
tor ripple current. The output capacitor impedance
must be significantly less than that of the battery to
ensure that it will absorb the ripple current. Both the
Maxim Integrated
15
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| MAX1757EVKIT | 功能描述:电池管理 Evaluation Kit for the MAX1757 MAX1758 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 |
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| MAX17582GTM+ | 功能描述:电流型 PWM 控制器 Dual-Phase Quick-PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
| MAX17582GTM+T | 功能描述:电流型 PWM 控制器 Dual-Phase Quick-PWM Controller RoHS:否 制造商:Texas Instruments 开关频率:27 KHz 上升时间: 下降时间: 工作电源电压:6 V to 15 V 工作电源电流:1.5 mA 输出端数量:1 最大工作温度:+ 105 C 安装风格:SMD/SMT 封装 / 箱体:TSSOP-14 |
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