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参数资料
| 型号： | MAX1729EUB |
| 厂商： | Maxim Integrated Products |
| 文件页数： | 9/12页 |
| 文件大小： | 0K |
| 描述： | IC REG BUCK BST ADJ 2.5MA 10UMAX |
| 产品培训模块： | Lead (SnPb) Finish for COTS Obsolescence Mitigation Program |
| 标准包装： | 50 |
| 类型： | 降压（降压），升压（升压） |
| 输出类型： | 可调式 |
| 输出数： | 1 |
| 输出电压： | 2.5 V ~ 16 V |
| 输入电压： | 2.7 V ~ 5.5 V |
| 电流 - 输出： | 2.5mA |
| 同步整流器： | 无 |
| 工作温度： | -40°C ~ 85°C |
| 安装类型： | 表面贴装 |
| 封装/外壳： | 10-TFSOP，10-MSOP（0.118"，3.00mm 宽） |
| 包装： | 管件 |
| 供应商设备封装： | 10-µMAX |
ECB and LCD Display Bias Supply with Accurate
Output Voltage and Temperature Compensation
? 1.228 = 36,840 ?
R3 = 1/2 ?
? 16.5mV/ ° C
? Tempco ?
R5 = ?
? 16. 5 mV / ° C = 150 k ?
2) Given the maximum output voltage (V MAX ) and mini-
mum output voltage (V MIN ), calculate values for R3 and
R4 as follows:
? R1 ?
R3 = 1/2 ? ? V FB
? V MAX – V MIN ?
R4 = R3
3) For first-order temperature compensation, calculate
R5 as shown below. (If temperature compensation is
not used, leave R5 open.)
? R1 ?
R5 = ?
2) V MAX = 10V and V MIN = 5V, therefore:
? 300k ? ?
? 5V ?
with R3 = 36.7k ? , then V MIN = 5.019V. Let R4 =
R3 = 36.7k ? .
3) Tempco = 33mV/°C, therefore:
? 300k ? ?
? 33mV/ ° C ?
4) If external circuitry limits the duty cycle to 90%, the
following equation is true:
V COMP = 1.228 ? 1 ?
? = 0.6754V
where Tempco is the negative temperature coefficient
needed to compensate the ECB or LCD display for
changes in temperature.
?
?
0.9 ?
2 ?
? ? ? ?
V COMP FB ? 1 – ? Duty Cycle ?
? ?
?
R3 + R4 ? ? ?
?
V COMP
= ? OUT + + FB ?
? R1 R5 ? V
R2 R3
? ?
+ +
? =
4) Solve for V COMP . The duty cycle used here corre-
sponds to the duty cycle that yields the maximum out-
put voltage, not including first-order temperature
compensation.
R4
=V
?
where a 90% duty cycle corresponds to Duty Cycle = 0.9.
5) Use the results from the above calculations to solve
for R2. (For applications not utilizing temperature com-
pensation, use 1 / R5 = 0.)
5) Solving for R2:
1 ? V V ? 1
FB
? 1 1 1 ? 1
? R1 R3 R5 ? 56560
With R2 = 56k ? , a duty cycle of 87.4% generates a
V OUT of 10V.
Component Selection
Inductors
=
? ?
1 ? V OUT V COMP V FB ?
V FB ? ? R1
R5 ? ?
+ +
R5 ?
?
1
R2
? 1
? R1
R3
1 1 ?
+ +
R3
Use a 220μH inductor to maximize output current
(2.5mA typical). Use an inductor with DC resistance
less than 10 ? and a saturation current exceeding
35mA. For lower peak inductor current, use a 470μH
inductor with DC resistance less than 20 ? and a satu-
ration current over 18mA. This limits output current to
typically less than 1mA. See Table 1 for a list of recom-
R1 =
= 300k ?
External Component Value Example
The example application requires the output voltage to
adjust between 5V and 10V, using the circuit shown in
Figure 3. The device in our example needs a tempera-
ture coefficient of 33mV/°C, which yields the following
results.
1) V MAX = 10V and I FB = 29.24μA is within the limits
and yields a reasonable resistor value, therefore:
10V ? 1.228V
29.24 μ A
mended inductors. The inductor should be connected
from the battery to the LX pin, as close to the IC as pos-
sible.
Capacitors
The equivalent series resistance (ESR) of output capac-
itor C2 directly affects output ripple. To minimize output
ripple, use a low-ESR capacitor. A physically smaller
capacitor, such as a common ceramic capacitor, mini-
mizes board space and cost while creating an output
ripple that’s acceptable in most applications. Refer to
Table 2 for recommended capacitor values.
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相关代理商/技术参数 |
参数描述 |
|---|---|
| MAX1729EUB-T | 功能描述:直流/直流开关转换器 ECB & LCD Display Bias Supply 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 |
| MAX172ACNG | 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 |
| MAX172ACNG+ | 功能描述:模数转换器 - ADC 12-Bit 100ksps 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 |
| MAX172ACWG | 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 |
| MAX172ACWG+ | 功能描述:模数转换器 - ADC 12-Bit 100ksps 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 |
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