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参数资料
| 型号： | MAX8725ETI+ |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 25/30页 |
| 文件大小： | 0K |
| 描述： | IC CHARGER BATTERY 28-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 60 |
| 功能： | 充电管理 |
| 电池化学： | 多化学 |
| 电源电压： | 8 V ~ 28 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（5x5） |
| 包装： | 托盘 |
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Multichemistry Battery Chargers with Automatic
System Power Selector
MOSFET Drivers
100
80
60
40
20
0
MAG
PHASE
0
-45
The DHI and DLO outputs are optimized for driving
moderately-sized power MOSFETs. The MOSFET drive
capability is the same for both the low-side and high-
side switches. This is consistent with the variable duty
factor that occurs in the notebook computer environ-
ment where the battery voltage changes over a wide
range. An adaptive dead-time circuit monitors the DLO
output and prevents the high-side FET from turning on
until DLO is fully off. There must be a low-resistance,
low-inductance path from the DLO driver to the
MOSFET gate for the adaptive dead-time circuit to work
-20
properly. Otherwise, the sense circuitry in the
-40
0.1
10
1k
100k
-90
10M
MAX1909/MAX8725 interpret the MOSFET gate as “off”
while there is still charge left on the gate. Use very
FREQUENCY (Hz)
Figure 10. CCS Loop Response
The loop transfer function is given by:
short, wide traces measuring 1.25mm to 2.5mm if the
MOSFET is 25mm from the device. Unlike the DLO out-
put, the DHI output uses a fixed-delay 50ns time to pre-
vent the low-side FET from turning on until DHI is fully
off. The same layout considerations should be used for
routing the DHI signal to the high-side FET.
LTF = GM IN × A CSS × RS 1 × GMS
R OGMS
1 + sR OGMS × C CS
Since the transition time for a p-channel switch can be
much longer than an n-channel switch, the dead time
prior to the high-side PMOS turning on is more pro-
Since:
GM IN =
1
A CSS × RS 1
nounced than in other synchronous step-down regula-
tors, which use high-side n-channel switches. On the
high-to-low transition, the voltage on the inductor ’s
“switched” terminal flies below ground until the low-side
the loop transfer function simplifies to:
switch turns on. A similar dead-time spike occurs on
the opposite low-to-high transition. Depending upon the
LTF = GMS
R OGMS
1 + sR OGMS × C CS
magnitude of the load current, these spikes usually
have a minor impact on efficiency.
The high-side driver (DHI) swings from SRC to 5V
The crossover frequency is given by:
below SRC and typically sources 0.9A and sinks 0.5A
from the gate of the p-channel FET. The internal pull-
f CO _ CS =
GMS
2 π C CS
high transistors that drive DHI high are robust, with a
2.0 Ω (typ) on-resistance.
The low-side driver (DLO) swings from DLOV to ground
For stability, choose a crossover frequency lower than
1/10th the switching frequency:
C CS = GMS / (2 π f CO_CS )
Choosing a crossover frequency of 30kHz and using
the component values listed in Figure 1 yields C CS >
5.4nF. Values for C CS greater than 10 times the mini-
mum value may slow down the input current-loop
response excessively. Figure 10 shows the Bode plot of
the input current-limit loop frequency response using
the values calculated above.
and typically sources 0.5A and sinks 0.9A from the gate
of the n-channel FET. The internal pulldown transistors
that drive DLO low are robust, with a 1.0 Ω (typ) on-
resistance. This helps prevent DLO from being pulled
up when the high-side switch turns on, due to capaci-
tive coupling from the drain to the gate of the low-side
MOSFET. This places some restrictions on the FETs
that can be used. Using a low-side FET with smaller
gate-to-drain capacitance can prevent these problems.
______________________________________________________________________________________
25
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8725ETI+ | 功能描述:电池管理 Multichemistry Battery 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 |
| MAX8725ETI+T | 功能描述:电池管理 Multichemistry Battery 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 |
| MAX8725ETI-T | 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 |
| MAX8725EVKIT | 功能描述:电池管理 Evaluation Kit for the MAX8725 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 |
| MAX8726EUE | 功能描述:LCD 驱动器 RoHS:否 制造商:Maxim Integrated 数位数量:4.5 片段数量:30 最大时钟频率:19 KHz 工作电源电压:3 V to 3.6 V 最大工作温度:+ 85 C 最小工作温度:- 20 C 封装 / 箱体:PDIP-40 封装:Tube |
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