- 您现在的位置：买卖IC网 > PDF目录299883 > SC804AMLTRT (Semtech Corporation) Fully Integrated 4.4V Lithium-Ion Battery Charger System with Timer PDF资料下载
参数资料
| 型号： | SC804AMLTRT |
| 厂商： | Semtech Corporation |
| 英文描述： | Fully Integrated 4.4V Lithium-Ion Battery Charger System with Timer |
| 中文描述： | 完全集成的4.4V锂离子电池充电器系统的计时器 |
| 文件页数： | 3/21页 |
| 文件大小： | 550K |
| 代理商： | SC804AMLTRT |
11
2005 Semtech Corp.
www.semtech.com
SC804A
PRELIMINARY
POWER MANAGEMENT
DRAFT
Applications Information (Cont.)
The choice of R
CT1 and RCT2 is somewhat arbitrary. The
simplest approach is to pick one and compute the other.
A good choice here is R
CT1 = 115kΩ, and RCT2 = 221kΩ, as
these standard 1% tolerance values produce the closest
match to the desired voltage divider ratio. With these
resistor nominal values,
which is, nominally, only 0.2% below the target value of
0.6591×V
VCC. The CTO network will present a load of only
15μA to a 5V charging adapter. The nominal impedance
presented to the CTO pin is R
CT1 || RCT2 = 75.6kΩ. Any
impedance on the order of 100k
Ω (or less) is acceptable.
Remote Kelvin Sensing at the Battery
The BSEN pin provides the positive Kelvin sensing voltage
feedback to the CV amplier and should be connected as
close to the battery + terminal as possible. Likewise, the
RGND pin should be connected directly to the negative
terminal of the battery. This allows the designer great
exibility in PCB layout and achieves greater accuracy
by sensing the battery voltage directly at the battery
terminals. When laying out the PCB, the designer should
route the BSEN and RGND trace directly to the battery
connection terminals, rather than just to the VOUT and
GND pins on the device.
Dropout Voltage
Dropout voltage is the smallest achievable difference
voltage between VCC and VOUT under a particular
operating condition.
Dropout voltage is encountered
during CC charging whenever the current limit of the
charging adapter is less than the SC804A FCI programmed
current. In this case, the adapter voltage (the SC804A
input voltage) will be pulled down to the battery voltage
(the SC804A output voltage) plus the dropout voltage.
Dropout voltage is the larger of two values: (1) the I-R
component, which is the output current multiplied by the
minimum VCC-to-VOUT path resistance (which is highly
temperature dependent), and (2) a regulated minimum
difference voltage, which is output voltage dependent
but is independent of the output current. The regulated
minimum dropout voltage results from the collapse of
internal voltage references as VOUT pulls VCC down to
near, or below, V
CV, creating a reduced output regulation
voltage approximately 200mV below VCC. Thus VCC
cannot be pulled down below VOUT + 200mV. The dropout
voltage will be larger than 200mV whenever the minimum
path resistance multiplied by the output current exceeds
200mV, but it cannot be smaller than 200mV.
This greatest-of-two-limit dropout voltage behavior is
evident in the dropout voltage typical performance plot.
When operating in Adjust Mode (next section), the
regulated minimum dropout voltage depends on the
programmed VOUT regulation voltage, and dropout also
varies with the actual output voltage during CC charging.
See Figure 4 for an illustration of dropout voltage data.
Adjust Mode
The SC804A can be congured for an output voltage
other than V
CV using Adjust (ADJ) Mode. In Adjust Mode
the output voltage is determined by an external resistor
divider from VOUT to BSEN. When BSEN is connected in
this fashion, V
VOUT (during Constant Voltage (CV) charging)
will be controlled such that the voltage at the BSEN pin
(V
BSEN) is the reference voltage VBSEN-ADJ.
The output voltage can be set to any voltage desired by
an appropriate choice of divider network resistors, within
the following limits. When the SC804A is programmed for
adjust mode, V
VOUT is required to be 150mV less than VVCC,
and V
VOUT is required to be 400mV greater than VBSEN.
V
VOUT within 150mV of VBSEN guarantees normal mode
operation. This implies that, for BSEN used as a Kelvin
sense of battery voltage, the product of the fast charge
current and the charge path resistance from VOUT to the
Kelvin sense point should not exceed 150mV to ensure
normal mode operation.
The SC804A Adjust Mode schematic is shown in Figures
3a and 3b. Referring to these schematics, the equation
for setting the output voltage is:
The capacitor C3 across R8 in the feedback network
introduces zero-pole frequency compensation for stability.
Place the zero according to the following equation to
ensure stability:
V
CTO =
VCC × R
CT2 = 0.6577 × VCC
R
CT1 + RCT2
R11 × C3 =
1
2 × 100kHz
VOUT = V
BSEN-ADJ_TYP x ( 1 +
R11 )
R12
相关PDF资料 |
PDF描述 |
|---|---|
| SC804A | Fully Integrated 4.4V Lithium-Ion Battery Charger System with Timer |
| SC804EVB | Fully Integrated Lithium-Ion Battery Charger System with Timer |
| SC804IMLTRT | Fully Integrated Lithium-Ion Battery Charger System with Timer |
| SC804 | Fully Integrated Lithium-Ion Battery Charger System with Timer |
| SC805EVB | Miniature Integrated High Current Lithium-Ion Battery Charger |
相关代理商/技术参数 |
参数描述 |
|---|---|
| SC804EVB | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Fully Integrated 4.4V Lithium-Ion Battery Charger System with Timer |
| SC804IML.TRT | 功能描述:IC LI-ION BATTERY CHRGR 16MLPQ RoHS:是 类别:集成电路 (IC) >> PMIC - 电池管理 系列:- 标准包装:1 系列:- 功能:充电管理 电池化学:锂离子（Li-Ion）、锂聚合物（Li-Pol） 电源电压:3.75 V ~ 6 V 工作温度:-40°C ~ 85°C 安装类型:表面贴装 封装/外壳:SC-74A，SOT-753 供应商设备封装:SOT-23-5 包装:剪切带 (CT) 产品目录页面:669 (CN2011-ZH PDF) 其它名称:MCP73831T-2ACI/OTCT |
| SC804IMLTRT | 制造商:Semtech Corporation 功能描述:Battery Charger Li-Ion 1500mA 4.2V 16-Pin MLPQ EP T/R |
| SC805 | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Miniature Integrated High Current Lithium-Ion Battery Charger |
| SC805A | 制造商:SEMTECH 制造商全称:Semtech Corporation 功能描述:Miniature Integrated High Current Lithium-Ion Battery Charger |
发布紧急采购，3分钟左右您将得到回复。