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参数资料
| 型号： | MAX8731AETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 27/32页 |
| 文件大小： | 0K |
| 描述： | IC SMBUS LVL2 BATT CHRGR 28TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 功能： | 充电管理 |
| 电池化学： | 多化学 |
| 电源电压： | 8 V ~ 26 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： | 带卷 (TR) |
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SMBus Level 2 Battery Charger
with Remote Sense
The crossover frequency is given by:
the device). Unlike the DLO output, the DHI output uses
a 50ns (typ) delay time to prevent the low-side MOSFET
f CO _ CS =
GMS
2 π C CS
from turning on until DHI is fully off. The same consider-
ations should be used for routing the DHI signal to the
high-side MOSFET.
For stability, choose a crossover frequency lower than
1/10 the switching frequency:
C CS = 5 × GMS /( 2 π f OSC )
Choosing a crossover frequency of 30kHz and using
the component values listed in Figure 1 yields C CS >
5.4nF. Values for CCS greater than 10 times the mini-
mum value may slow down the current-loop response
excessively. Figure 12 shows the Bode plot of the input
current-limit-loop frequency response using the values
calculated above.
MOSFET Drivers
The DHI and DLO outputs are optimized for driving
moderate-sized power MOSFETs. The MOSFET drive
capability is the same for both the low-side and high-
sides 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. There must be a low-resistance, low-inductance
The high-side driver (DHI) swings from LX to 5V above
LX (BST) and has a typical impedance of 3 Ω sourcing
and 1 Ω sinking. The low-side driver (DLO) swings from
DLOV to ground and has a typical impedance of 1 Ω
sinking and 3 Ω sourcing. This helps prevent DLO from
being pulled up when the high-side switch turns on, due
to capacitive coupling from the drain to the gate of the
low-side MOSFET. This places some restrictions on the
MOSFETs that can be used. Using a low-side MOSFET
with smaller gate-to-drain capacitance can prevent
these problems.
Design Procedure
MOSFET Selection
Choose the n-channel MOSFETs according to the maxi-
mum required charge current. The MOSFETs must be
able to dissipate the resistive losses plus the switching
losses at both V DCIN(MIN) and V DCIN(MAX) .
For the high-side MOSFET, the worst-case resistive
power losses occur at the maximum battery voltage
and minimum supply voltage:
path from the DLO driver to the MOSFET gate to pre-
vent shoot-through. Otherwise, the sense circuitry in the
MAX8731A interprets the MOSFET gate as “off” while
PD CONDUCTION ( HighSide ) =
V FBS _
V CSSP
× I CHG 2 × R DS ( ON )
there is still charge left on the gate. Use very short,
wide traces measuring 10 to 20 squares or less
(1.25mm to 2.5mm wide if the MOSFET is 25mm from
Generally a low-gate charge high-side MOSFET is pre-
ferred to minimize switching losses. However, the
R DS(ON) required to stay within package power-dissi-
100
80
60
40
20
0
MAG
PHASE
0
-45
pation limits often limits how small the MOSFET can be.
The optimum occurs when the switching (AC) losses
equal the conduction (R DS(ON) ) losses. Calculating the
power dissipation in N1 due to switching losses is diffi-
cult since it must allow for difficult quantifying factors
that influence the turn-on and turn-off times. These fac-
tors include the internal gate resistance, gate charge,
threshold voltage, source inductance, and PCB layout
characteristics. The following switching-loss calculation
provides a rough estimate and is no substitute for
breadboard evaluation, preferably including a verifica-
-20
tion using a thermocouple mounted on N1:
-40
0.1
10
1k
FREQUENCY (Hz)
100k
-90
10M
PD SWITCHING ( High Side ) =
1
2
× t Trans × V DCIN × I CHG × f SW
Figure 12 . CCS Loop Response
______________________________________________________________________________________
27
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX8731AEVKIT+ | 功能描述:电源管理IC开发工具 MAX8731A Eval Kit RoHS:否 制造商:Maxim Integrated 产品:Evaluation Kits 类型:Battery Management 工具用于评估:MAX17710GB 输入电压: 输出电压:1.8 V |
| MAX8731AEVSYS | 功能描述:电池管理 Evaluation System for the MAX8731A (includes an EVKit and the Maxim SMBUSMON2 board) 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 |
| MAX8731ETI+ | 制造商:Maxim Integrated Products 功能描述:CHGR MULTI-CHEM 8A 0V TO 19.2V 28TQFN - Rail/Tube |
| MAX8731ETI+T | 制造商:Maxim Integrated Products 功能描述:CHGR MULTI-CHEM 8A 0V TO 19.2V 28TQFN - Tape and Reel |
| MAX8731EVKIT | 功能描述:电池管理 SMBus Level 2 Battery Charger with Remote Sense 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 |
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