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| 型号： | MAX8664AEEP+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 23/26页 |
| 文件大小： | 0K |
| 描述： | IC CNTRLR DUAL OUT 20-QSOP |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 电源 |
| 电流 - 电源： | 1.4mA |
| 电源电压： | 4.5 V ~ 28 V |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 20-SSOP（0.154"，3.90mm 宽） |
| 供应商设备封装： | 20-QSOP |
| 包装： | 带卷 (TR) |
Low-Cost, Dual-Output, Step-Down
Controller with Fast Transient Response
The high-side MOSFET(s) operate as duty-cycle control
switches and have the following major losses: the chan-
nel conduction loss (P HSCC ), the overlapping switching
loss (P HSSW ), and the drive loss (P HSDR ). The maxi-
mum power dissipation could occur either at V IN(MAX)
or V IN(MIN) :
interfere with circuit performance and generate EMI. To
dampen this ringing, a series RC snubber circuit is
added across each low-side switch. Below is the pro-
cedure for selecting the value of the series RC circuit.
Connect a scope probe to measure V LX_ to GND and
observe the ringing frequency, f R .
P HSCC ( MAX ) =
V OUT
V IN ( MIN )
× I 2 LOAD ( MAX ) × R DS ( ON )
Find the capacitor value (connected from LX_ to GND)
that reduces the ringing frequency by half.
The circuit parasitic capacitance (C PAR ) at LX_ is then
Use R DS(ON) at T J(MAX) :
equal to 1/3 the value of the added capacitance above.
The circuit parasitic inductance (L PAR ) is calculated by:
× C PAR
P HSSW ( MAX ) = V IN ( MAX ) × I LOAD ( MAX ) ×
Q GD
I GATE
× f S
L PAR =
( 2 π f R )
1
2
I GATE ?
where I GATE is the average DH driver output-current
capability determined by:
0 . 5 × V VL
R DS ( ON )( DR ) + R GATE
where R DS(ON)(DR) is the DH_ driver’s on-resistance
(see the Electrical Characteristics) and R GATE is the
internal gate resistance of the MOSFET (~ 2 Ω ):
The resistor for critical dampening (R SNUB ) is equal to
2 π x f R x L PAR . Adjust the resistor value up or down to
tailor the desired damping and the peak-voltage excur-
sion.
The capacitor (C SNUB ) should be at least 2 to 4 times
the value of the C PAR to be effective. The power loss of
the snubber circuit is dissipated in the resistor
(P RSNUB ) and can be calculated as:
P RSNUB = C SNUB × ( V IN ) × f SW
P HSDR = Q G × V GS × f S ×
R GATE
R GATE + R DS ( ON )( DR )
2
where V IN is the input voltage and f SW is the switching
frequency. Choose an R SNUB power rating that meets
the specific application’s derating rule for the power
where V GS ≈ V VL .
The high-side MOSFET(s) do not have body diode con-
duction loss, unless the converter is sinking current.
When sinking current, calculate this loss as
P HSDC(MAX) = I LOAD(MAX) x V F x (2 x t DT + t WD ) x f S ,
where t WD is about 130ns.
Allow an additional 20% for losses due to MOSFET out-
put capacitances and low-side MOSFET body diode
reverse-recovery charge dissipated in the high-side
MOSFET(s). Refer to the MOSFET data sheet for ther-
mal resistance specifications to calculate the PCB area
needed to maintain the desired maximum operating
dissipation calculated.
Setting the Overcurrent Threshold
Connect a resistor from ILIM_ to the drain of the high-
side MOSFET(s) to set the overcurrent protection
threshold. ILIM_ sinks 50μA (typ) through this resistor.
When the drain-source voltage exceeds the voltage
drop across this resistor during the high-side MOS-
FET(s) on-time, overcurrent protection is triggered. To
set the output current level where overcurrent protec-
tion is triggered (I LIMIT ), calculate the value of the ILIM_
resistor as follows:
junction temperature with the above calculated power
dissipations.
R ILIM _ =
R DS( ON)HS × I LIMIT
50 μ A
MOSFET Snubber Circuit
Fast switching transitions cause ringing because of res-
onating circuit parasitic inductance and capacitance at
the switching nodes. This high-frequency ringing
occurs at LX’s rising and falling transitions and can
where R DS(ON)HS is the maximum on-resistance of the
high-side MOSFET(s) at +25°C. At higher tempera-
tures, the ILIM current increases to compensate for the
temperature coefficient of the high-side MOSFET(s).
______________________________________________________________________________________
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| MAX8664BEEP+T | 功能描述:DC/DC 开关控制器 Dual-Output Step Step-Down Controller RoHS:否 制造商:Texas Instruments 输入电压:6 V to 100 V 开关频率: 输出电压:1.215 V to 80 V 输出电流:3.5 A 输出端数量:1 最大工作温度:+ 125 C 安装风格: 封装 / 箱体:CPAK |
| MAX8664EVKIT+ | 功能描述:电源管理IC开发工具 MAX8664 Evan 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 |
| MAX8667ETEAA+ | 功能描述:直流/直流开关转换器 1.5MHz Dl Step-Down DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
| MAX8667ETEAA+T | 功能描述:直流/直流开关转换器 1.5MHz Dl Step-Down DC/DC Converter RoHS:否 制造商:STMicroelectronics 最大输入电压:4.5 V 开关频率:1.5 MHz 输出电压:4.6 V 输出电流:250 mA 输出端数量:2 最大工作温度:+ 85 C 安装风格:SMD/SMT |
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