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參數(shù)資料
| 型號： | MAX2003A |
| 廠商： | Maxim Integrated Products, Inc. |
| 元件分類： | 基準(zhǔn)電壓源/電流源 |
| 英文描述： | Fast-Charge Battery Chargers(NICD/NIMH,可充電池數(shù)1~16個,電池快速充電器) |
| 中文描述： | 快速充電電池充電器（鎳鎘/鎳氫電池，可充電池數(shù)1?16個，電池快速充電器） |
| 文件頁數(shù)： | 12/20頁 |
| 文件大?。?/td> | 191K |
| 代理商： | MAX2003A |
M
The top-off charge is done at 1/8 the fast-charge rate.
For the MAX2003, the MOD pin is activated in every 34
second period to supply current to the battery for 4
seconds (MOD oscillates for 4 seconds and stays low
for 30 seconds) (Figure 7). If external regulation is used
(SNS tied to ground), MOD stays high for 4 seconds
and low for 30 seconds (Figure 8). This top-off process
continues until the fast-charge timeout (Table 4) is
exceeded, or if a maximum temperature or maximum
voltage condition is detected. The MAX2003A is slightly
modified to turn the MOD pin on for 0.5sec in every 4
second period. This shorter on-time reduces battery
heat and increases charge acceptance. During the top-
off charge, the CHG pin will cycle low (LED on) for
0.125sec and high (LED off) for 0.125sec.
T ric kle-Charge
A trickle-charge is applied to the battery after fast-
charge and top-off charge have terminated to compen-
sate for self discharge. There are two methods of trickle
charge: constant and pulsed.
Pulsed T ric kle-Charge (MAX 2003A)
The MAX2003A provides a pulsed trickle-charge to the
battery by turning on the MOD pin briefly during a fixed
period of time. The duty cycle of the pulse is a function of
the programmable inputs TM1 and TM2 (Table 4 ). The
MAX2003A does not use the trickle resistor to provide the
trickle charge. However, the trickle resistor cannot be
entirely omitted because it is also used for the battery-
detect circuitry.
Constant T ric kle-Charge (MAX 2003)
The MAX2003 provides a steady trickle-charge to the
battery by connecting a resistor from the DC supply to
the positive battery terminal. This resistor has a dual
purpose, in that it provides a trickle-charge and pulls
the BAT pin above the MCV when the battery is absent.
The trickle-charge rate depends on the type of battery
used. For NiCd batteries, a nominal trickle-charge rate
would be C/16, and NiMH batteries could use a rate of
C/40. The resistor value used depends on the maxi-
mum DC voltage and the typical battery voltage. For
example, a six-cell 800mAh NiCd pack with a nominal
voltage of 1.2V per cell would have a total voltage of
1.2V x 6V = 7.2V. If the DC supply voltage used is 14V,
the voltage across the trickle resistor would be 14.0V -
7.2V = 6.8V. The trickle current needed would be C/16
= 800 / 16 = 50mA. The trickle resistor would therefore
be R
TR
= 6.8V / 50mA
≈
150
. Similar calculations
should be made for NiMH batteries using C/40 as the
trickle-charge rate.
If a trickle-charge is not needed, a higher value of trick-
le resistor (like 100k
) can be selected to sense the
battery insertion.
Charge S tatus
The CHG pin is connected to a LED that indicates the
operating mode. Table 5 summarizes the different
charge conditions.
_______________________Design Guide
Using the circuit of Figure 1 as an example, the follow-
ing nine steps show how to design a 1.7A switch-mode
fast-charger that can charge a Duracell DR17 (NiMH
six-cell battery pack with a 1700mAh capacity).
1) Select DC Power Supply
. The first step is to select
the DC power supply (such as a wall cube). The mini-
mum supply voltage should have a supply equal to
about 2V per cell, plus 1V headroom for external cir-
cuitry ((2V/cell) + 1V). The minimum supply voltage
must be greater than 6V. If, as in our example, there
are six cells, a minimum supply of about 13V is needed
((6 cells x 2V) + 1V).
2) Determine Charge Rate
. The charge rate, or fast-
charge current (I
FAST
), is determined by two factors:
the capacity of the battery, and the time in which the
user wants the battery to be charged. The battery man-
ufacturer recommends a maximum fast-charge rate,
which must not be exceeded.
Capacity of Battery (mAh)
I
FAST
(mA) = ————————————
Charge Time (h)
For example, if a 1700mAh battery needs to be charged in
two hours (C/2), a fast-charge current of at least 850mA is
needed. A charge rate of C/2 will ideally charge a battery
in two hours but, because of inefficiencies in a battery’s
chemical processes, the time could be 30% to 40% more.
Our example circuit (Figure 1) charges the Duracell bat-
tery pack at a C rate of 1.7A, which should fully charge a
discharged battery in approximately 80 minutes.
NiCd/NiMH Battery Fast-Charge Controllers
12
______________________________________________________________________________________
Table 5. Charge Status
LED on for 0.125sec, off for
0.125sec
Charge Complete and Top-
Off
LED on
Fast-Charge
LED on for 1.375sec, off for
0.125sec
Discharge-Before-Charge
LED on for 0.125sec, off for
1.375sec
Charge Pending
Charge State
Battery Absent
LED off
CHG LED Status
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| MAX2003AC/D | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:NiCd/NiMH Battery Fast-Charge Controllers |
| MAX2003ACPE | 制造商:Maxim Integrated Products 功能描述: |
| MAX2003ACSE | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
| MAX2003ACWE | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:NiCd/NiMH Battery Fast-Charge Controllers |
| MAX2003ACWE+ | 制造商:Rochester Electronics LLC 功能描述: 制造商:Maxim Integrated Products 功能描述: |
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