- 您现在的位置：买卖IC网 > PDF目录15546 > MAX8903JETI+T (Maxim Integrated Products)IC DC/DC CHARGER LI+ 2A 28-TQFN PDF资料下载
参数资料
| 型号： | MAX8903JETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 22/30页 |
| 文件大小： | 0K |
| 描述： | IC DC/DC CHARGER LI+ 2A 28-TQFN |
| 产品培训模块： | Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 系列： | Smart Power Selector™ |
| 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： | 4.1 V ~ 16 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 28-WFQFN 裸露焊盘 |
| 供应商设备封装： | 28-TQFN-EP（4x4） |
| 包装： | 带卷 (TR) |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页当前第22页第23页第24页第25页第26页第27页第28页第29页第30页
MAX8903A–E/G/H/J/N/Y
2A 1-Cell Li+ DC-DC Chargers
for USB and Adapter Power
where:
R T = The resistance in ? of the thermistor at tempera-
ture T in Celsius
R 25 = The resistance in ? of the thermistor at +25°C
β = The material constant of the thermistor, which typi-
cally ranges from 3000K to 5000K
T = The temperature of the thermistor in °C
Table 3 shows the MAX8903_ THM temperature limits
for different thermistor material constants.
Some designs might prefer other thermistor temperature
and let the system continue to operate with external power.
If the THM pin is tied to GND (voltage at THM is below 3%
of VL), the thermistor option is disabled and the system
does not respond to the thermistor input. In those cases, it
is assumed that the system has its own temperature sens-
ing, and halts changing through CEN when the tempera-
ture is outside of the safe charging range.
Power Dissipation
Table 4. Package Thermal Characteristics
28-PIN 4mm x 4mm THI N QFN
limits. Threshold adjustment can be accommodated by
changing R TB , connecting a resistor in series and/or in
SINGLE-LAYER PCB
MULTILAYER PCB
parallel with the thermistor, or using a thermistor with dif-
ferent β . For example, a +45°C hot threshold and 0°C
cold threshold can be realized by using a thermistor
with a β of 4250 and connecting 120k ? in parallel. Since
the thermistor resistance near 0°C is much higher than it
is near +50°C, a large parallel resistance lowers the
cold threshold, while only slightly lowering the hot
Continuous
Power
Dissipation
θ JA
θ JC
1666.7mW
Derate 20.8mW/°C
above +70°C
48°C/W
3°C/W
2286mW
Derate 28.6mW/°C
above +70°C
35°C/W
3°C/W
threshold. Conversely, a small series resistance raises
the hot threshold, while only slightly raising the cold
threshold. Raising R TB lowers both the cold and hot
thresholds, while lowering R TB raises both thresholds.
Note that since VL is active whenever valid input power
is connected at DC or USB, thermistor bias current
flows at all times, even when charging is disabled ( CEN
= high). When using a 10k ? thermistor and a 10k ?
pullup to VL, this results in an additional 250μA load.
This load can be reduced to 25μA by instead using a
100k ? thermistor and 100k ? pullup resistor.
Power Enable on Battery Detection
The power enabled on battery detection function allows
the MAX8903B/MAX8903E/MAX8903G to automatically
enable/disable the USB and DC power inputs when the
battery is applied/removed. This function utilizes the
battery pack’s integrated thermistor as a sensing mech-
anism to determine when the battery is applied or
removed. With this function, MAX8903B/MAX8903E/
MAX8903G-based systems shut down when the battery
is removed regardless of whether external power is
available at the USB or DC power inputs.
The MAX8903B/MAX8903E/MAX8903G implement the
power enabled on battery detection function with the ther-
mistor detector comparator as shown in Figure 7. If no bat-
tery is present, the absence of the thermistor allows R TB to
pull THM to VL. When the voltage at the THM pin increases
above 87% of VL, it is assumed that the battery has been
removed and the system powers down. However, there is
also the option to bypass this thermistor sensing option
completely, and so retain the ability to remove the battery
22
Minimum SYS Output Capacitor
Based on the version of the MAX8903_, the SYS load
regulation is either 25mV/A or 40mV/A. The 25mV/A ver-
sions achieve better load regulation by increasing the
feedback loop gain. To ensure feedback stability with
this higher gain, a larger SYS output capacitor is
required. Devices with 25m/V SYS load regulation
require 22μF SYS output capacitor whereas devices
with 40m/V only require 10μF. See Table 6 for more
information about the various versions of the
MAX8903_.
Inductor Selection for
Step-Down DC-DC Regulator
The MAX8903_'s control scheme requires an external
inductor (L OUT ) from 1.0μH to 10μH for proper operation.
This section describes the control scheme and the consid-
erations for inductor selection. Table 5 shows recommend-
ed inductors for typical applications. For assistance with
the calculations needed to select the optimum inductor for
a given application, refer to the spreadsheet at:
www.maximintegrated.com/design/tools/calcula -
tors/files/MAX8903-INDUCTOR-DESIGN.xls .
The MAX8903 step-down DC-DC regulator implements a
control scheme that typically results in a constant switch-
ing frequency (f SW ). When the input voltage decreases to
a value near the output voltage, high duty cycle operation
occurs and the device can operate at less than f SW due
to minimum off-time (t OFFMIN ) constraints. In high duty
cycle operation, the regulator operates with t OFFMIN and
a peak current regulation. Similarly, when the input
voltage is too high to allow f SW operation due to minimum
Maxim Integrated
相关PDF资料 |
PDF描述 |
|---|---|
| MAX8903HETI+T | IC DC/DC CHARGER LI+ 2A 28-TQFN |
| 1-1435953-0 | PATCHCORD CAT6 RED&BLK BOOT 10' |
| ASPI-104S-7R0M-T | INDUCTOR POWER 7.0UH SMD |
| MAX8903GETI+T | IC DC-DC CHARGER LI+ 2A 28TQFN |
| 1499740-4 | CABLE/ASSY AMPTRAC SHLD CAT6 4FT |
相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8903NETI+ | 功能描述:电池管理 2A 1-Cell Li+ DC-DC Charger for USB and Adapter Power RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX8903NETI+T | 功能描述:电池管理 2A 1-Cell Li+ DC-DC Charger for USB and Adapter Power RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX8903YETI+ | 功能描述:电池管理 Dual AC/USB Powered 1-Cell Li+ Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX8903YETI+C67 | 功能描述:电池管理 RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
| MAX8903YETI+T | 功能描述:电池管理 Dual AC/USB Powered 1-Cell Li+ Charger RoHS:否 制造商:Texas Instruments 电池类型:Li-Ion 输出电压:5 V 输出电流:4.5 A 工作电源电压:3.9 V to 17 V 最大工作温度:+ 85 C 最小工作温度:- 40 C 封装 / 箱体:VQFN-24 封装:Reel |
发布紧急采购，3分钟左右您将得到回复。