数控电源电阻选择

shangdawei 发表于 2014-11-29 16:48:40

shangdawei 发表于 2014-11-29 16:50:21

DAC = 0V : Vo = 1.233 * ( 2200 / 390 ) + 1.233 * ( 1 + 2200/180 ) = 6.95V + 16.303V = 23.253V

DAC = 1.233V : V0 = 1.233 * ( 1 + 2200/180 ) = 16.303V

shangdawei 发表于 2014-11-29 16:53:25

When the converter is programmed to the minimum output voltage,
the DAC output (DO) equals the reference voltage of 1.233 V (typ).Therefore, only the feedback resistor network (R1) and (R2) determines the output voltage under these conditions.
This gives the minimum output voltage possible and can be calculated as:The maximum output voltage is determined as the DAC output (DO) is set to 0 V:
the DAC output DO (pin 3) one-step where one step is typically 19.6 mV. ( 0..63 : 6 Bit DAC )

The DAC output pin (DO) drives an external resistor (R3) connected to the external feedback
divider. The DO output has a typical output voltage range from 0 V to Vref (1.233V). If the DO output voltage is
set to 0 V, the external resistor (R3) is more or less in parallel to the lower feedback resistor (R2) giving the
highest output voltage. Programming the DO output to Vref gives the lowest output voltage. Internally, a 6-bit DAC
is used with 64-steps and 0 as the first step. This gives a typical voltage step of 19.6 mV which is calculated as:

A voltage step on DO of 19.6mV (typ) changes the output voltage by one step and is calculated as:

The possible output voltage range is determined by selecting R1, R2 and R3.A possible larger output voltage range gives a larger output voltage step size.The smaller the possible output voltage range, the smaller the output voltage step size.

shangdawei 发表于 2014-11-29 16:56:32

Variable Control Voltage Output Voltage Adjust

This method is accomplished by connecting a variable control voltage through a resistor, R(adjust), to J3−1.
The equations provided below calculate R2 and R(adjust) where:

For example, if VO,max= 19 V, VO,min = 17 V, V(adjust),min = 0 V, V(adjust),max = 3.3 V, and R1 = 1 MΩ,

then R2 = 72.4 kΩ, and R(adjust) = 1.65 MΩ.

When V(adjust) = 0 V then VO = 19 V. When V(adjust) = 3.3 V then VO = 17 V.

dwl65 发表于 2014-12-1 21:31:21

全部是English啊，数学这东西啊。得细心看才行。先保存下来先。

maithon 发表于 2019-7-13 22:31:43

为什么不可以调节vref呢？

下载文件 发表于 2019-7-16 12:47:17

ADS仿真吗？

qiujiefu3 发表于 2020-5-4 00:11:09

全部是English

robter 发表于 2020-6-10 08:33:19

很好的参考资料

HWX0309 发表于 2020-6-13 03:52:55

谢谢分享计算方法。

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