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參數(shù)資料
| 型號： | DS2714 |
| 廠商： | Maxim Integrated Products, Inc. |
| 英文描述： | Quad Loose Cell NiMH Charger |
| 中文描述： | 4節(jié)散裝NiMH電池充電器 |
| 文件頁數(shù)： | 10/12頁 |
| 文件大小： | 221K |
| 代理商： | DS2714 |
DS2714: Quad Loose Cell NiMH Charger
10 of 12
CELL TESTS
Two types of tests are performed to detect primary Alkaline and Lithium cells or defective NiMH or NiCd secondary
cells. The first test checks the absolute closed circuit cell voltage (V
ON
), and the second test checks the difference
in open circuit cell voltage (V
OFF
) and (V
ON
). V
ON
for each cell is compared to the VBAT-MAX2 threshold once every
2 seconds. During fast charge, V
ON
- V
OFF
of each cell is compared to the cell test threshold, V
CTST
. If V
ON
- V
OFF
>
V
CTST
, the cell test fails. Cells are tested individually so that a single improper or defective cell can be detected
quickly. V
CTST
is set by the resistance from the CTST pin to ground. The nominal sensitivity of 100mV is set by
connecting an 80k
ohm resistor between CTST and V
SS
. The impedance threshold can be set from 32mV to
400mV. The following formula approximates the setting for the impedance threshold
V
CTST
= 8000/R
(value in volts)
-
V AND FLAT VOLTAGE TERMINATION
During Fast charge, - V detection is performed by comparing successive voltage measurements for a drop of 2mV
in the cell voltage. A Hold-off period for - V detection begins at the start of Fast charging and prevents false
termination in the first few minutes of the charge cycle. Once the hold-off period expires, cell voltage
measurements are acquired every 16th charge time slot (approximately 31 seconds, during the CCx off time).
When a newly acquired voltage measurement is greater than any previous one, the new value is retained as the
maximum value. When the cell voltage no longer increases, the maximum value is retained and compared against
subsequent values. If the cell voltage drops below the - V threshold, V
- V
, (2mV typ), Fast charging is terminated. If
the cell voltage remains flat such that the maximum value persists for a period of 16 minutes (t
FLAT
), Fast charge
terminates and Top-Off charging begins.
TOP-OFF, PRE-CHARGE AND MAINTENANCE
In Top-off and Pre-charge modes, the charger scales the cell current to 1/16 of the DC current set by the current
source, i.e, one charge pulse for every 16 main clock pulses, or one in four available time slots for a given cell. The
ratio of average Top-off/Pre-charge current to average fast charge current is 0.286. When the charge timer expires
in Top-Off, the charger enters Maintenance and delivers 1/128 of the DC charge source current to the cells (one
time slot in every 32 available to that cell). This is slightly more than 3% of the average DC Fast Charge current.
Maintenance charge remains continuous until power is removed, the cell(s) are removed or the DS2714 is cycled
into and out of suspend mode by floating the TMR pin.
CCX OUTPUTS
The CC1 through CC4 pins operate as open-drain outputs that drive active low to connect the charge source to the
NiMH cells. During charge, the behavior of these outputs depends on the charge states of the cells and on how
many cells have been installed.
FAST CHARGE
Referring to the application circuit shown in Figure 3, CC1 controls the PNP switch that gates current to the cell in
slot 1. CC2 controls the PNP switch that gates current to the cell in slot 2, and so on. During Fast charge, current is
gated to each slot sequentially, with charge pulses occurring in alternating time frames. The cell in one slot charges
while the others relax. Each cell skips a charge pulse every 16 of its allocated charge time slots (approximately
once every 31 seconds) to facilitate independent testing of the open and closed circuit cell voltages (V
OFF
and V
ON
,
respectively). Since the charge regime of each cell is independent, one cell may complete a charge phase before
the other without affecting the charging of the other cells. In the case of an improper or faulty cell (ex. alkaline)
being inserted along with proper cells (NiMH or NiCd), charging of the improper cell would be stopped, while the
proper cells will be charged to full.
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相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| DS2714E+ | 功能描述:電池管理 Quad Loose Cell NiMH 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 |
| DS2714E+T&R | 制造商:Maxim Integrated Products 功能描述: 制造商:Maxim Integrated Products 功能描述:QUAD LOOSECELL NIMHCHRGER TSSOP20LF - Tape and Reel 制造商:Maxim Integrated Products 功能描述:IC NIMH CHARGER QUAD 20TSSOP 制造商:Maxim Integrated Products 功能描述:Battery Management Quad Loose Cell NiMH Chargers |
| DS2714E+T&R | 功能描述:電池管理 Quad Loose Cell NiMH 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 |
| DS2714E+TR | 制造商:MAXIM 制造商全稱:Maxim Integrated Products 功能描述:Quad Loose Cell NiMH Charger |
| DS2714EVKIT+ | 制造商:Maxim Integrated Products 功能描述:DS2714 EVAL KIT - Boxed Product (Development Kits) |
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