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參數(shù)資料
| 型號(hào)： | Si9730 |
| 廠商： | Vishay Intertechnology,Inc. |
| 英文描述： | Dual-Cell Lithium Ion Battery Control IC(兩節(jié)鋰電池充電控制芯片) |
| 中文描述： | 雙鋰離子電池控制IC（兩節(jié)鋰電池充電控制芯片） |
| 文件頁(yè)數(shù)： | 11/13頁(yè) |
| 文件大?。?/td> | 355K |
| 代理商： | SI9730 |
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Si9730
Vishay Siliconix
FaxBack 408-970-5600, request 70658
www.siliconix.com
S-60752—Rev. D, 05-Apr-99
11
battery charger/load (this is notin parallel with the battery,
because of the switch). A 10-μF capacitor is recommended for
this purpose; see Figure 8.
Selecting a Current Sense Resistor
The current sense resistor should be selected based on the
maximum current the battery can source or charge at; above
this current, the Si9730 will open the switch, disconnecting the
battery from its load or charger.
R
sense
= V
ILIMIT
/I
ILIMIT
≈
28 mV/I
ILIMIT
Of course, the resistor must be rated to take the power
dissipated in it as well:
P
RSENSE
= I
ILIMIT
V
ILIMIT
≈
28 mV I
ILIMIT
For example, suppose that the maximum current the battery
will see is 1.8 A. Then, I
LIMIT
might be chosen to be 2 A. We
would then select a resistor of
R
SENSE
= 28 mV/2 A = 14 m
The power dissipation in this resistor is
P
RSENSE
= 28 mV 2 A = 56 mW
and so a 100mW surface mount resistor would be suitable.
Another possibility is to use a thin copper trace as the sense
resistor. The copper has a temperature coefficient of 0.39%/
°
C, but this is partially compensated for by the temperature
coefficient of the current limit comparator in the Si9730, which
is 0.18%/
°
C. A simple formula for selecting a trace to act as a
current sensor is:
For example, to get a 14-m
. resistor, we need length/width =
28; with a trace width of 0.01", the length of the trace should
be 0.28".
MOSFET Selection
Two MOSFETs in series, with their sources and gates
connected together, are used as the switch. This prevents
current from flowing in either direction when the gate is low; if
only one MOSFET were used, the body diode could conduct
current in the opposing direction.
LITTLE FOOT MOSFETs are recommended for this
application, because of their size, performance and cost
benefits. SO-8 and TSSOP-8 MOSFETs allow for space
efficient designs with performance equal to or better than their
DPAK and TO-220 predecessors. Further, their availability
from multiple sources permits a cost effective solution.
There are two important parameters to consider in MOSFET
selection: gate threshold voltage; and on-resistance, which
determines power dissipation.
Even when the DCO pin of the Si9730 is low, the specification
allows its value to be as high as 0.4 V. If this voltage were
close to the gate threshold voltage, leakage current through
the MOSFETs could be hundreds of microamps, which would
result in the battery quickly becoming discharged. To ensure
that leakage is minimized, n-channel MOSFETs with a
minimum gate threshold voltage of 0.8 V should be chosen.
On resistance of the MOSFETs needs to be selected to limit
power dissipation into the MOSFETs’ package. For example,
a dual MOSFET SO-8 package is rated at 2 W, and a dual
MOSFET TSSOP-8 package is rated at 1 W (both at 25
°
C; if
the ambient temperature is higher, the allowable power
dissipation in these packages is less). For example, if the
maximum current is 2 A, and a dual MOSFET SO-8 package
is being used, the maximum on-resistance of the two
MOSFETs in series must not exceed
1 W = (2 A)
2
R
ON
or R
ON
= 0.25
; each MOSFET can be allotted half of this,
R
ON
= 125 m
. Account must also be taken of the fact that
MOSFETs’ on-resistance is a function of temperature; a
conservative approach would give a discount of 1/3, R
ON
=
125 m
* (2/3) = 80 m
per MOSFET.
A
Semiconductors supplies, can be found later in this book.
list
of
recommended
MOSFETs,
which
TEMIC
R
0.5m
---------------
1 oz. Copper
(
)
×
=
N-CHANNEL MOSFET SELECTION GUIDE
Part
Number
r
DS (on)
(
)
@ V
GS
=
10 V
r
DS(on)
(
)
@ V
GS
=
4.5 V
I
D
(A)
V
GS(th)
(V)
Config.
Package
Recommended
Application
Current (A) @ 25
°
C
Si4410DY
0.0135
0.020
10
1.0
Single
SO-8
9
Si4412DY
0.028
0.042
7
1.0
Single
SO-8
6.3
Si6434DQ
0.028
0.042
5.6
1.0
Single
TSSOP-8
4.9
Si4936DY
0.037
0.055
5.8
1.0
Dual
SO-8
3.5
Si9936DY
0.050
0.080
5
1.0
Dual
SO-8
2.9
Si6954DQ
0.065
0.095
3.9
1.0
Dual
TSSOP-8
1.9
相關(guān)PDF資料 |
PDF描述 |
|---|---|
| SI9731DB | UP Controlled Battery Charger For 1-Cell Li-ion or 1-Cell to 3-Cell NiCd/NiMH Batteries |
| SI9731DQ | UP Controlled Battery Charger For 1-Cell Li-ion or 1-Cell to 3-Cell NiCd/NiMH Batteries |
| SI9731 | 渭P Controlled Li-ion Battery Charger Pulse Charges 1 to 3 Cells Integrated MOSFETs |
| Si9731 | μP Controlled Battery Charger For 1-Cell Li-ion or 1-Cell to 3-Cell NiCd/NiMH Batteries(用于1節(jié)鋰電池或1-3節(jié)鎳氫/鎳鎘電池的μP控制的電池充電器) |
| Si9750 | In-Rush Current Limit MOSFET Driver(輸入電壓工作范圍2.9-13V，限流MOSFET驅(qū)動(dòng)器) |
相關(guān)代理商/技術(shù)參數(shù) |
參數(shù)描述 |
|---|---|
| SI9730ABY | 功能描述:電池管理 Battery Controller 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 |
| SI9730ABY-E3 | 功能描述:電池管理 Li Batt Controller 4.15-4.25V OC Detect 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 |
| SI9730ABY-T1 | 功能描述:電池管理 Li Batt Controller 4.15-4.25V OC Detect 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 |
| SI9730ABY-T1-E3 | 功能描述:電池管理 Li Batt Controller 4.15-4.25V OC Detect 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 |
| SI9730BBY | 功能描述:電池管理 Battery Controller 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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