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參數(shù)資料
| 型號： | MAX1909 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Multichemistry Battery Charger with Automatic System Power Selector |
| 中文描述： | 多種化學(xué)類型電池充電器，自動選擇系統(tǒng)電源 |
| 文件頁數(shù)： | 16/29頁 |
| 文件大?。?/td> | 551K |
| 代理商： | MAX1909 |
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M
Multichemistry Battery Charger with Automatic
System Power Selector
16
______________________________________________________________________________________
Detailed Description
The MAX1909 includes all of the functions necessary to
charge Li+, NiMH, and NiCd batteries. A high-efficien-
cy synchronous-rectified step-down DC-to-DC convert-
er is used to implement a precision constant-current,
constant-voltage charger with input current limiting. The
DC-to-DC converter uses external P-channel/N-channel
MOSFETs as the buck switch and synchronous rectifier
to convert the input voltage to the required charge cur-
rent and voltage. The charge current and input current-
limit sense amplifiers have low-input-referred offset
errors and can use small-value sense resistors. The
MAX1909 features a voltage-regulation loop (CCV) and
two current-regulation loops (CCI and CCS). The CCV
voltage-regulation loop monitors BATT to ensure that its
voltage never exceeds the voltage set by VCTL. The
CCI battery current-regulation loop monitors current
delivered to BATT to ensure that it never exceeds the
current limit set by ICTL. A third loop (CCS) takes con-
trol and reduces the charge current when the sum of
the system load and the input-referred charge current
exceeds the power source current limit set by CLS.
Tying CLS to the reference voltage provides a 7.5A
input current limit with a 10m
sense resistor.
The ICTL, VCTL, and CLS analog inputs set the charge
current, charge voltage, and input current limit, respec-
tively. For standard applications, internal set points for
ICTL and VCTL provide a 3A charge current using a
15m
sense resistor and a 4.2V per-cell charge volt-
age. The variable for controlling the number of cells is
set with the MODE input. The
PKPRES
input is used for
battery-pack detection, and provides shutdown control
from a logic signal or external thermistor.
Based on the presence or absence of the AC adapter,
the MAX1909 automatically provides an open-drain logic
output signal ACOK and selects the appropriate source
for supplying power to the system. A P-channel load
switch controlled from the PDL output and a similar P-
channel source switch controlled from the PDS output are
used to implement this function. Using the MODE control
input, the MAX1909 can be programmed to perform a
relearning, or conditioning, cycle in which the battery is
isolated from the charger and completely discharged
through the system load. When the battery reaches 100%
depth of discharge, it is recharged to full capacity.
The circuit shown in Figure 1 demonstrates a simple
hardwired application, while Figure 2 shows a typical
application for smart-battery systems with variable
charge current and source switch configuration that sup-
ports battery conditioning. Smart-battery systems typical-
ly use a host μC to achieve this added functionality.
Setting the Charge Voltage
The MAX1909 uses a high-accuracy voltage regulator
for charge voltage. The VCTL input adjusts the battery
output voltage. In default mode (VCTL = LDO), the
overall accuracy of the charge voltage is ±0.5%. VCTL
is allowed to vary from 0 to 3.6V, which provides a 10%
adjustment range of the battery voltage. Limiting the
adjustment range reduces the sensitivity of the charge
voltage to external resistor tolerances from ±2% to
±0.2%. The overall accuracy of the charge voltage is
better than ±1% when using ±1% resistors to divide
down the reference to establish VCTL. The per-cell bat-
tery termination voltage is a function of the battery
chemistry and construction. Consult the battery manu-
facturer to determine this voltage. The battery voltage is
calculated by the equation:
where V
REF
= 4.2235V, and CELL is the number of cells
selected with the MAX1909
’
s trilevel MODE control
input. When MODE is tied to the LDO output, CELL = 4.
When MODE is left floating, CELL = 3. When MODE is
tied to ground, the charger enters conditioning mode,
which is used to isolate the battery from the charger
and discharge it through the system load. See the
Conditioning Mode
section. The internal error amplifier
(GMV) maintains voltage regulation (See Figure 3 for
Functional Diagram
). The voltage-error amplifier is
compensated at CCV. The component values shown in
Figures 1 and 2 provide suitable performance for most
applications. Individual compensation of the voltage
regulation and current-regulation loops allow for opti-
mal compensation. See the Compensation section.
Setting the Charge Current
The voltage on the ICTL input sets the maximum
voltage across current-sense resistor RS2, which in turn
determines the charge current. The full-scale differen-
tial voltage between CSIP and CSIN is 75mV; thus, for a
0.015
sense resistor, the maximum charge current is
5A. In default mode (ICTL = LDO), the sense voltage is
45mV with an overall accuracy of ±5%. The charge cur-
rent is programmed with ICTL using the equation:
The input range for ICTL is 0.9V to 3.6V. The charger
shuts down if ICTL is forced below 0.8V (typ). When
choosing current-sense resistor RS2, note that it must
have a sufficient power rating to handle the full-load
I
RS
V
3 6
.
V
CHG
ICTL
=
×
0 075
.
2
V
CELL V
V
V
BATT
REF
VCTL
=
+
1 8
9 52
.
.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX1909ETI | 功能描述:電池管理 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 |
| MAX1909ETI+ | 功能描述:電池管理 Multichemistry Battery Chargers 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 |
| MAX1909ETI+T | 功能描述:電池管理 Multichemistry Battery Chargers 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 |
| MAX1909ETI-T | 功能描述:電池管理 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 |
| MAX1909EVKIT | 功能描述:電池管理 Evaluation Kit for the MAX1909 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 |
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