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| 型号： | MAX1909ETI+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 27/30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： | 2,500 |
| 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： | 带卷 (TR) |
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Multichemistry Battery Chargers with Automatic
System Power Selector
Choose a low-side MOSFET that has the lowest possi-
ble on-resistance (R DS(ON) ), comes in a moderate-
sized package, and is reasonably priced. Make sure
that the DLO gate driver can supply sufficient current to
1.5
3 CELLS
support the gate charge and the current injected into
the parasitic gate-to-drain capacitor caused by the
high-side MOSFET turning on; otherwise, cross-con-
duction problems can occur.
The MAX1909/MAX8725 have an adaptive dead-time cir-
cuit that prevents the high-side and low-side MOSFETs
from conducting at the same time (see the MOSFET
Drivers section). Even with this protection, it is still possi-
ble for delays internal to the MOSFET to prevent one
MOSFET from turning off when the other is turned on.
1.0
0.5
0
V DCIN = 19V
VCTL = ICTL = LDO
4 CELLS
Select devices that have low turn-off times. To be
conservative, make sure that P1(t DOFF(MAX) ) -
8
9
10 11 12 13 14 15 16 17 18
V BATT (V)
N1(t DON(MIN) ) < 40ns. Failure to do so may result in
efficiency-killing shoot-through currents. If delay mis-
match causes shoot-through currents, consider adding
extra capacitance from gate to source on N1 to slow
down its turn-on time.
MOSFET Power Dissipation
Worst-case conduction losses occur at the duty factor
Figure 11. Ripple Current vs. Battery Voltage (MAX1909)
following switching-loss calculation provides only a very
rough estimate and is no substitute for breadboard
evaluation, preferably including a verification using a
thermocouple mounted on P1:
extremes. For the high-side MOSFET, the worst-case
power dissipation (PD) due to resistance occurs at the
minimum supply voltage:
PD ( P 1 _ Switching ) =
V DCIN(MAX ) 2 × C RSS × f SW × I LOAD
2 I GATE
PD ( P 1 ) = ? BATT ? ? LOAD ?
? V ? ? I ? 2
? V DCIN ? ? 2 ?
× R DS ( ON )
where C RSS is the reverse transfer capacitance of P1,
and I GATE is the peak gate-drive source/sink current.
For the low-side MOSFET (N1), the worst-case power
? V DCIN ? ? ? ?
PD ( N 1 ) = ? 1 ? ? BATT ? ? ? LOAD ? × R DS ( ON )
? ?
Generally, a small high-side MOSFET is desired to
reduce switching losses at high input voltages.
However, the R DS(ON) required to stay within package
power-dissipation limits often limits how small the
MOSFET can be. The optimum occurs when the switch-
ing (AC) losses equal the conduction (I 2 R DS(ON) )
losses. High-side switching losses do not usually
become an issue until the input is greater than approxi-
mately 15V. Switching losses in the high-side MOSFET
can become an insidious heat problem when maximum
AC adapter voltages are applied, due to the squared
term in the CV 2 f switching-loss equation. If the high-
side MOSFET that was chosen for adequate R DS(ON) at
low supply voltages becomes extraordinarily hot when
subjected to V DCIN(MAX), then choose a MOSFET with
lower losses. Calculating the power dissipation in P1
due to switching losses is difficult since it must allow for
difficult quantifying factors that influence the turn-on
and turn-off times. These factors include the internal
gate resistance, gate charge, threshold voltage, source
inductance, and PC board layout characteristics. The
dissipation always occurs at maximum input voltage:
? ? V ? ? ? I ? 2
2 ?
Choose a Schottky diode (D1, Figure 2) with a forward
voltage low enough to prevent the N1 MOSFET body
diode from turning on during the dead time. As a gen-
eral rule, a diode with a DC current rating equal to 1/3rd
the load current is sufficient. This diode is optional and
can be removed if efficiency is not critical.
Inductor Selection
The charge current, ripple, and operating frequency
(off-time) determine the inductor characteristics.
Inductor L1 must have a saturation current rating of at
least the maximum charge current plus 1/2 of the ripple
current ( Δ IL):
I SAT = I CHG + (1/2) Δ IL
______________________________________________________________________________________
27
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1909EVKIT | 功能描述:电池管理 Evaluation Kit for the MAX1909 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 |
| MAX190ACNG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX190ACNG+ | 功能描述:模数转换器 - ADC 12Bit 75ksps 5V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX190ACWG | 功能描述:模数转换器 - ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
| MAX190ACWG+ | 功能描述:模数转换器 - ADC 12Bit 75ksps 5V Precision ADC RoHS:否 制造商:Texas Instruments 通道数量:2 结构:Sigma-Delta 转换速率:125 SPs to 8 KSPs 分辨率:24 bit 输入类型:Differential 信噪比:107 dB 接口类型:SPI 工作电源电压:1.7 V to 3.6 V, 2.7 V to 5.25 V 最大工作温度:+ 85 C 安装风格:SMD/SMT 封装 / 箱体:VQFN-32 |
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