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参数资料
| 型号： | LTC4008EGN |
| 厂商： | Linear Technology |
| 文件页数： | 13/24页 |
| 文件大小： | 0K |
| 描述： | IC BATT CHARGER CTRLR 4A 20SSOP |
| 标准包装： | 55 |
| 功能： | 充电管理 |
| 电池化学： | 多化学 |
| 电源电压： | 6 V ~ 28 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 20-SSOP |
| 包装： | 管件 |
LTC4008
APPLICATIONS INFORMATION
I CHARGE ( MAX ) =
R PROG =
Charger Current Programming
The basic formula for charging current is:
V REF ? 3.01k Ω / R PROG – 0.035 V
R SENSE
V REF = 1.19V. This leaves two degrees of freedom: R SENSE
and R PROG . The 3.01k input resistors must not be altered
since internal currents and voltages are trimmed for this
value. Pick R SENSE by setting the average voltage between
CSP and BAT to be close to 100mV during maximum
charger current. Then R PROG can be determined by solving
the above equation for R PROG .
V REF ? 3 . 01 k Ω
R SENSE ? I CHARGE ( MAX ) + 0 . 035 V
Table 2. Recommended R SNS and R PROG Resistor Values
increased also to improve stability and prevent large
overshoot currents during start-up conditions. Charging
current will be proportional to the duty cycle of the switch
with full current at 100% duty cycle and zero current when
Q1 is off.
Maintaining C/10 Accuracy
The C/10 comparator threshold that drives the FLAG pin
has a ?xed threshold of approximately V PROG = 400mV.
This threshold works well when R PROG is 26.7k, but will
not yield a 10% charging current indication if R PROG is
a different value. There are situations where a standard
value of R SENSE will not allow the desired value of charging
current when using the preferred R PROG value. In these
cases, where the full-scale voltage across R SENSE is within
±20mV of the 100mV full-scale target, the input resistors
connected to CSP and BAT can be adjusted to provide the
I MAX (A)
1.0
2.0
3.0
4.0
R SENSE (Ω) 1%
0.100
0.050
0.033
0.025
R SENSE (W)
0.25
0.25
0.5
0.5
R PROG (kΩ) 1%
26.7
26.7
26.7
26.7
desired maximum programming current as well as the
correct FLAG trip point.
For example, the desired max charging current is 2.5A but
the best R SENSE value is 0.033Ω. In this case, the volt-
age across R SENSE at maximum charging current is only
Charging current can be programmed by pulse width
modulating R PROG with a switch Q1 to R PROG at a frequency
higher than a few kHz (Figure 5). C PROG must be increased
to reduce the ripple caused by the R PROG switching. The
compensation capacitor at I TH will probably need to be
LTC4008
PROG
10
82.5mV, normally R PROG would be 30.1k but the nominal
FLAG trip point is only 5% of maximum charging current.
If the input resistors are reduced by the same amount as
the full-scale voltage is reduced then, R4 = R5 = 2.49k
and R PROG = 26.7k, the maximum charging current is
still 2.5A but the FLAG trip point is maintained at 10%
of full scale.
There are other effects to consider. The voltage across the
current comparator is scaled to obtain the same values as
5V
0V
R PROG
Q1
2N7002
C PROG
R Z
102k
the 100mV sense voltage target, but the input referred sense
voltage is reduced, causing some careful consideration of
the ripple current. Input referred maximum comparator
threshold is 117mV, which is the same ratio of 1.4x the
4008 F05
Figure 5. PWM Current Programming
DC target. Input referred I REV threshold is scaled back to
–24mV. The current at which the switcher starts will be
reduced as well so there is some risk of boost activity.
These concerns can be addressed by using a slightly larger
inductor to compensate for the reduction of tolerance to
ripple current.
4008fb
13
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| LTC4008EGN#PBF | 功能描述:IC BATT CHARGER CTRLR 4A 20SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 其它有关文件:STC3100 View All Specifications 特色产品:STC3100 - Battery Monitor IC 标准包装:4,000 系列:- 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MiniSO 包装:带卷 (TR) 其它名称:497-10526-2 |
| LTC4008EGN#TR | 功能描述:IC CTRLR CHARGR PWM CC/CV 20SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:电池监控器 电池化学:碱性，锂离子，镍镉，镍金属氢化物 电源电压:1 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-6 包装:带卷 (TR) |
| LTC4008EGN#TRPBF | 功能描述:IC BATT CHARGER CTRLR 4A 20SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:电池监控器 电池化学:碱性，锂离子，镍镉，镍金属氢化物 电源电压:1 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-6 包装:带卷 (TR) |
| LTC4008EGN-1 | 功能描述:IC BATT CHARGER CTRLR 4A 20SSOP RoHS:否 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 产品培训模块:Lead (SnPb) Finish for COTS Obsolescence Mitigation Program 标准包装:2,500 系列:- 功能:电池监控器 电池化学:碱性，锂离子，镍镉，镍金属氢化物 电源电压:1 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SOT-23-6 供应商设备封装:SOT-6 包装:带卷 (TR) |
| LTC4008EGN-1#PBF | 功能描述:IC BATT CHARGER CTRLR 4A 20SSOP RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 其它有关文件:STC3100 View All Specifications 特色产品:STC3100 - Battery Monitor IC 标准包装:4,000 系列:- 功能:燃料，电量检测计/监控器 电池化学:锂离子（Li-Ion） 电源电压:2.7 V ~ 5.5 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:8-TSSOP，8-MSOP（0.118"，3.00mm 宽） 供应商设备封装:8-MiniSO 包装:带卷 (TR) 其它名称:497-10526-2 |
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