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參數(shù)資料
| 型號： | MAX1758EAI |
| 廠商： | MAXIM INTEGRATED PRODUCTS INC |
| 元件分類： | 電源管理 |
| 英文描述： | Stand-Alone, Switch-Mode Li Battery Charger with Internal 28V Switch |
| 中文描述： | 1-CHANNEL POWER SUPPLY SUPPORT CKT, PDSO28 |
| 封裝： | 5.30 MM, 0.65 MM PITCH, SSOP-28 |
| 文件頁數(shù)： | 15/17頁 |
| 文件大?。?/td> | 224K |
| 代理商： | MAX1758EAI |
M
Stand-Alone, Switch-Mode
Li+ Battery Charger with Internal 28V Switch
______________________________________________________________________________________
15
cell voltage limit battery regulation voltage is deter-
mined, the VADJ voltage is calculated by the equation:
V
VADJ
= (9.5 V
BATTR
/ N) - (9.0 x V
REF
)
CELL is the programming input for selecting cell count
N. Table 2 shows how CELL is connected to charge 1,
2, 3, or 4 cells.
Setting the Charging Current Limit
A resistor-divider from REF to GND sets the voltage at
ISETOUT (V
ISETOUT
). This determines the charging cur-
rent during the current-regulation (fast-charge) mode.
The full-scale charging current is 1.5A.
The charging current (I
CHG
) is, therefore:
Connect ISETOUT to REF to get the full-scale current
limit.
Setting the Input Current limit
A resistor-divider from REF to GND sets the voltage at
ISETIN (V
ISETIN
). This sets the maximum source current
allowed at any time during charging. The source cur-
rent 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:
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, note 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 f
OSC
is the switching frequency (300kHz).
The peak inductor current is given by:
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:
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 x
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 consideration of RMS current and power
I
I
D
D
CIN
CHG
2
I
I
LIR
2
PEAK
ISETOUT
+
1
=
L
V
V
V
V
x f
x I
x LIR
BATT
DCIN MAX
(
BATT
DCIN MAX
(
OSC
CHG
)
)
=
)
I
I
V
V
IN
FSS
ISETIN
REF
=
I
A
V
V
CHG
ISETOUT
REF
1 5
=
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1758EAI+ | 功能描述:電池管理 Li+ Battery Charger w/28V Switch 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 |
| MAX1758EAI+T | 功能描述:電池管理 Li+ Battery Charger w/28V Switch 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 |
| MAX1758EAI-T | 功能描述:電池管理 Li+ Battery Charger w/28V Switch 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 |
| MAX1758EVKIT | 功能描述:電池管理 Evaluation Kit for the MAX1757 MAX1758 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 |
| MAX17595ATE+ | 功能描述:電流型 PWM 控制器 AC/DC-DC/DC Peak Current-Mode Cnvrtr RoHS:否 制造商:Texas Instruments 開關(guān)頻率:27 KHz 上升時間: 下降時間: 工作電源電壓:6 V to 15 V 工作電源電流:1.5 mA 輸出端數(shù)量:1 最大工作溫度:+ 105 C 安裝風(fēng)格:SMD/SMT 封裝 / 箱體:TSSOP-14 |
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