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参数资料
| 型号： | MAX1889ETE+T |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 17/32页 |
| 文件大小： | 0K |
| 描述： | IC PWR SUP TRPL LCD 16-TQFN |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 2,500 |
| 应用： | 控制器，TFT LCD |
| 输入电压： | 2.7 V ~ 5.5 V |
| 输出数： | 3 |
| 输出电压： | 2.7 V ~ 13 V |
| 工作温度： | 0°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 16-WQFN 裸露焊盘 |
| 供应商设备封装： | 16-TQFN-EP（5x5） |
| 包装： | 带卷 (TR) |
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Triple-Output TFT LCD Power Supply
with Fault Protection
? I
?
× V
P LR = I ( LAVG )2 R L ? ? MAIN MAIN ? R L
Inductor Selection
The minimum inductance value, peak current rating,
series resistance, and size are factors to consider when
selecting the inductor. These factors influence the con-
verter ’ s efficiency, maximum output load capability,
transient response time, and output voltage ripple. For
most applications, values between 3.3μH and 20μH
work best with the MAX1889 ’ s switching frequencies.
The maximum load current, input voltage, output volt-
age, and switching frequency determine the inductor
value. For a given load current, higher inductor value
results in lower peak current and, thus, less output rip-
ple, but degrades the transient response and possibly
increases the size of the inductor. The equations pro-
vided here include a constant defined as LIR, which is
the ratio of the peak-to-peak inductor current ripple to
the average DC inductor current. For a good compro-
mise between the size of the inductor, power loss, and
output voltage ripple, select an LIR of 0.3 to 0.5. The
inductance value is then given by:
The power loss due to the inductor ’ s series resistance
(P LR ) can be approximated by the following equation:
2
? V IN ?
where I L(AVG) is the average inductor current and R L is
the inductor ’ s series resistance. For best performance,
select inductors with resistance less than the internal
N-channel MOSFET ’ s on-resistance (0.25 ? typ). To
minimize radiated noise in sensitive applications, use a
shielded inductor.
Output Capacitor
The output capacitor affects the circuit stability and out-
put voltage ripple. A 10μF ceramic capacitor works well
in most applications. Depending on the output capaci-
tor chosen, feedback compensation may be required
or desirable to increase the loop-phase margin or
increase the loop bandwidth for transient response
(see the Feedback Compensation section).
??
? V
? V IN ( TYP ) ?
L = ?
? MAIN ?
2
? V MAIN - V IN ( TYP ) ? ? 1 ?
?? ?? ? ? η
? I MAIN ( MAX ) f OSC ? ? LIR ?
The total output voltage ripple has two components: the
capacitive ripple caused by the charging and discharg-
ing of the output capacitance, and the ohm ripple due to
the capacitor ’ s equivalent series resistance (ESR):
V RIPPLE ( C ) ≈ MAIN ? MAIN IN ?
?? ? 1 +
I PEAK = ? ? ? ?
2 ? ? η ?
? ?
?
where η is the efficiency, f OSC is the oscillator frequency
(see the Electrical Characteristics ), and I MAIN includes
the primary load current and the input supply currents
for the charge pumps. Considering the typical applica-
tion circuit, the maximum average DC load current
(I MAIN(MAX) ) is 200mA with a 9V output. Based on the
above equations, and assuming 85% efficiency and a
switching frequency of 1MHz, the inductance value is
9.4μH for an LIR of 0.3. The inductance value is 5.6μH
for an LIR of 0.5. The inductance in the standard appli-
cation circuit is chosen to be 6.8μH.
The inductor ’ s peak current rating should be higher than
the peak inductor current throughout the normal operat-
ing range. The peak inductor current is given by:
? I MAIN ( MAX ) V MAIN ? ? LIR ? ? 1 ?
? V IN ( MIN )
Under fault conditions, the inductor current can reach the
internal LX current limit (see the Electrical Characteristics ).
However, soft saturation inductors and the controller ’ s fast
current-limit circuitry protect the device from failure during
such a fault condition.
The inductor ’ s DC resistance can significantly affect
efficiency due to conduction losses in the inductor.
V RIPPLE = V RIPPLE ( ESR ) + V RIPPLE ( C )
V RIPPLE ( ESR ) ≈ I PEAK R ESR ( COUT ), and
I ? V - V ?
C OUT ? V MAIN f OSC ?
where I PEAK is the peak inductor current (see the Inductor
Selection section). For ceramic capacitors, the output volt-
age ripple is typically dominated by V RIPPLE(C ). The volt-
age rating and temperature characteristics of the output
capacitor must also be considered.
Step-Up Regulator Compensation
The loop stability of a current-mode step-up regulator
can be analyzed using a small-signal model. In continu-
ous conduction mode (CCM), the loop-gain transfer
function consists of a dominant pole, a high-frequency
pole, a right-half-plane (RHP) zero, and an ESR zero. In
the case of ceramic output capacitors, the ESR zero is at
a very high frequency.
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相关代理商/技术参数 |
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|---|---|
| MAX1889EVKIT | 功能描述:电源管理IC开发工具 MAX1889 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 |
| MAX188ACAP | 功能描述:模数转换器 - ADC Integrated Circuits (ICs) 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 |
| MAX188ACAP+ | 功能描述:模数转换器 - ADC 12-Bit 8Ch 133ksps 5.25V 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 |
| MAX188ACAP+T | 功能描述:模数转换器 - ADC 12-Bit 8Ch 133ksps 5.25V 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 |
| MAX188ACAP-T | 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 |
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