LM399H : 高精度参考电压源

• • LM399

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01 参考电压源

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一、前言

??手边这颗高精度参考电压源是从一台分析仪器中拆卸下来的。 ?它的型号为 LM399H。?它具有四个引脚， ?似乎外部的塑料壳仅仅是其保温层。?在外壳边缘有一个凸起， 这样便可以确定它的管脚功能定义。?数据手册上给出了从凸起开始， 逆时针为管脚1到4. ?下面对于这颗参考电压源的功能特性进行测试。

二、测试结果

??为了便于测量， 使用四芯扁平电缆将 LM399H 引到一个 4PIN 的插针上。 ?这样便可以借助于面包板进行测量。?根据焊接的顺序， 可以确定四个插针的管脚。?红色定义了第一个管脚， ?从上往下分别是1,2,3,4 管脚。

??根据数据手册中定义的功能， ?在 1,2 管教之间为一个6.95V的稳压二极管。 ?4， 2 之间存在一个二极管。 ?4,3 之间存在一个加热齐纳二极管。 ?从3 到 1 之间存在一个导通回路。 ?使用数字万用表测量， ?在1,2 之间可以测量一个单向导通的通路， ?前向导通电压为 0.891V。 ?在4,2 之间存在一个单向导通二极管。 ?前向导通电压为 0.691V。 ?在3,4之间 也是一个单向导通回路。 ?前向导通电压为 0.575V .。

??测量1，2 管脚之间的稳压特性。 ?使用一个上拉电阻 连接1管脚到正电源，?电阻使用10k欧姆， ?利用万用表测量1,2 之间的电压。 ?电压幅值为 6.938V。?下面通过编程， 逐步升高工作电压， 测量1,2 管脚电压变化情况。

??记录工作电压与输出电压曲线， ?当输入电压大于10V之后， 输出电压便开始稳压在7V左右。 在7V 到10V之间， 输出电压随着输入电压的增加逐步上升。 ?绘制 10V 到 15V之间的曲线。 看起来这个变化还是蛮复杂的。 ?后面输出电压上升， 应该是稳压二极管电流增加引起的。 ?通过计算这个曲线的变化率， ?再根据负载电阻为 10kΩ， ?可以计算出 LM199的动态电阻为 2.39Ω。 ?对照LM399数据手册， ?这比手册中给出的 1欧姆的动态电阻大了2倍多。

▲ 图1.2.1 输入电压与输出电压

vdim=[0.0000,0.0754,0.1508,0.2261,0.3015,0.3769,0.4523,0.5276,0.6030,0.6784,0.7538,0.8291,0.9045,0.9799,1.0553,1.1307,1.2060,1.2814,1.3568,1.4322,1.5075,1.5829,1.6583,1.7337,1.8090,1.8844,1.9598,2.0352,2.1106,2.1859,2.2613,2.3367,2.4121,2.4874,2.5628,2.6382,2.7136,2.7889,2.8643,2.9397,3.0151,3.0905,3.1658,3.2412,3.3166,3.3920,3.4673,3.5427,3.6181,3.6935,3.7688,3.8442,3.9196,3.9950,4.0704,4.1457,4.2211,4.2965,4.3719,4.4472,4.5226,4.5980,4.6734,4.7487,4.8241,4.8995,4.9749,5.0503,5.1256,5.2010,5.2764,5.3518,5.4271,5.5025,5.5779,5.6533,5.7286,5.8040,5.8794,5.9548,6.0302,6.1055,6.1809,6.2563,6.3317,6.4070,6.4824,6.5578,6.6332,6.7085,6.7839,6.8593,6.9347,7.0101,7.0854,7.1608,7.2362,7.3116,7.3869,7.4623,7.5377,7.6131,7.6884,7.7638,7.8392,7.9146,7.9899,8.0653,8.1407,8.2161,8.2915,8.3668,8.4422,8.5176,8.5930,8.6683,8.7437,8.8191,8.8945,8.9698,9.0452,9.1206,9.1960,9.2714,9.3467,9.4221,9.4975,9.5729,9.6482,9.7236,9.7990,9.8744,9.9497,10.0251,10.1005,10.1759,10.2513,10.3266,10.4020,10.4774,10.5528,10.6281,10.7035,10.7789,10.8543,10.9296,11.0050,11.0804,11.1558,11.2312,11.3065,11.3819,11.4573,11.5327,11.6080,11.6834,11.7588,11.8342,11.9095,11.9849,12.0603,12.1357,12.2111,12.2864,12.3618,12.4372,12.5126,12.5879,12.6633,12.7387,12.8141,12.8894,12.9648,13.0402,13.1156,13.1910,13.2663,13.3417,13.4171,13.4925,13.5678,13.6432,13.7186,13.7940,13.8693,13.9447,14.0201,14.0955,14.1709,14.2462,14.3216,14.3970,14.4724,14.5477,14.6231,14.6985,14.7739,14.8492,14.9246,15.0000]
odim=[0.0002,0.0747,0.1500,0.2254,0.3007,0.3760,0.4513,0.5256,0.6009,0.6761,0.7515,0.8268,0.9021,0.9774,1.0527,1.1281,1.2034,1.2788,1.3541,1.4294,1.5048,1.5801,1.6552,1.7306,1.8059,1.8813,1.9566,2.0319,2.1072,2.1826,2.2579,2.3332,2.4085,2.4839,2.5592,2.6345,2.7097,2.7851,2.8604,2.9357,3.0110,3.0863,3.1616,3.2370,3.3124,3.3877,3.4630,3.5384,3.6137,3.6888,3.7642,3.8396,3.9149,3.9902,4.0654,4.1408,4.2162,4.2915,4.3669,4.4422,4.5175,4.5928,4.6672,4.7423,4.8177,4.8930,4.9682,5.0435,5.1188,5.1941,5.2694,5.3446,5.4199,5.4950,5.5701,5.6453,5.7201,5.7951,5.8700,5.9447,6.0191,6.0931,6.1665,6.2389,6.3090,6.3740,6.4272,6.4613,6.4829,6.5002,6.5161,6.5313,6.5462,6.5609,6.5756,6.5902,6.6048,6.6193,6.6339,6.6485,6.6630,6.6776,6.6921,6.7067,6.7212,6.7358,6.7503,6.7649,6.7794,6.7939,6.8085,6.8231,6.8377,6.8521,6.8664,6.8805,6.8944,6.9077,6.9207,6.9332,6.9451,6.9564,6.9671,6.9773,6.9872,6.9967,7.0058,7.0147,7.0233,7.0317,7.0392,7.0396,7.0399,7.0401,7.0402,7.0401,7.0400,7.0398,7.0396,7.0396,7.0396,7.0397,7.0397,7.0398,7.0398,7.0399,7.0399,7.0400,7.0400,7.0401,7.0401,7.0402,7.0402,7.0403,7.0403,7.0404,7.0404,7.0405,7.0405,7.0405,7.0405,7.0406,7.0406,7.0407,7.0407,7.0407,7.0407,7.0407,7.0408,7.0408,7.0408,7.0409,7.0409,7.0409,7.0409,7.0409,7.0409,7.0410,7.0410,7.0410,7.0410,7.0410,7.0411,7.0411,7.0411,7.0411,7.0411,7.0411,7.0412,7.0412,7.0412,7.0412,7.0412,7.0412,7.0413,7.0413,7.0413,7.0413,7.0413,7.0413]

#!/usr/local/bin/python
# -*- coding: gbk -*-
#============================================================
# TEST1.PY                     -- by Dr. ZhuoQing 2024-01-09
#
# Note:
#============================================================

from headm import *
from tsmodule.tsvisa        import *

dm3068open()

vdim = linspace(0, 15, 200)
odim = []

for v in vdim:
    dh1766volt1(v)
    time.sleep(1.5)
    ov = dm3068vdc()
    odim.append(ov)
    printff(v, ov)

    tspsave('meas1', vdim=vdim, odim=odim)


dh1766volt1(9)
plt.plot(vdim, odim, lw=3)

plt.xlabel("Input Voltage(V)")
plt.ylabel("Output(V)")
plt.grid(True)
plt.tight_layout()
plt.show()





#------------------------------------------------------------
#        END OF FILE : TEST1.PY
#============================================================

▲ 图1.2.2 输入10V之后的输出电压变化

三、加热电流

??下面测量内部加热齐纳管电流特性。 ?将 3管脚连接到工作电源。 测量不同工作电压下， 工作电流的变化情况 。?由于稳压管本身的工作电流比较小， ?所以测量到的工作电流大部分是加热齐纳二极管的工作电流。 ?测量结果来看， ?只有当工作电压超过 8.5V之后， 工作电流才大幅度增加， 这说明加热器件的确是一个齐纳二极管。 ?当电流达到最大值之后， ?随着电压增加， 加热电流下降。 这说明内部具有恒温功能， 于是， 加热功率维持恒定， 从而使得消耗的加热功率保持恒定。

▲ 图1.3.1 不同电压下的加热电流

vdim=[0.0000,0.0754,0.1508,0.2261,0.3015,0.3769,0.4523,0.5276,0.6030,0.6784,0.7538,0.8291,0.9045,0.9799,1.0553,1.1307,1.2060,1.2814,1.3568,1.4322,1.5075,1.5829,1.6583,1.7337,1.8090,1.8844,1.9598,2.0352,2.1106,2.1859,2.2613,2.3367,2.4121,2.4874,2.5628,2.6382,2.7136,2.7889,2.8643,2.9397,3.0151,3.0905,3.1658,3.2412,3.3166,3.3920,3.4673,3.5427,3.6181,3.6935,3.7688,3.8442,3.9196,3.9950,4.0704,4.1457,4.2211,4.2965,4.3719,4.4472,4.5226,4.5980,4.6734,4.7487,4.8241,4.8995,4.9749,5.0503,5.1256,5.2010,5.2764,5.3518,5.4271,5.5025,5.5779,5.6533,5.7286,5.8040,5.8794,5.9548,6.0302,6.1055,6.1809,6.2563,6.3317,6.4070,6.4824,6.5578,6.6332,6.7085,6.7839,6.8593,6.9347,7.0101,7.0854,7.1608,7.2362,7.3116,7.3869,7.4623,7.5377,7.6131,7.6884,7.7638,7.8392,7.9146,7.9899,8.0653,8.1407,8.2161,8.2915,8.3668,8.4422,8.5176,8.5930,8.6683,8.7437,8.8191,8.8945,8.9698,9.0452,9.1206,9.1960,9.2714,9.3467,9.4221,9.4975,9.5729,9.6482,9.7236,9.7990,9.8744,9.9497,10.0251,10.1005,10.1759,10.2513,10.3266,10.4020,10.4774,10.5528,10.6281,10.7035,10.7789,10.8543,10.9296,11.0050,11.0804,11.1558,11.2312,11.3065,11.3819,11.4573,11.5327,11.6080,11.6834,11.7588,11.8342,11.9095,11.9849,12.0603,12.1357,12.2111,12.2864,12.3618,12.4372,12.5126,12.5879,12.6633,12.7387,12.8141,12.8894,12.9648,13.0402,13.1156,13.1910,13.2663,13.3417,13.4171,13.4925,13.5678,13.6432,13.7186,13.7940,13.8693,13.9447,14.0201,14.0955,14.1709,14.2462,14.3216,14.3970,14.4724,14.5477,14.6231,14.6985,14.7739,14.8492,14.9246,15.0000]
odim=[0.0002,0.0747,0.1500,0.2254,0.3007,0.3761,0.4513,0.5256,0.6010,0.6762,0.7515,0.8268,0.9021,0.9775,1.0528,1.1281,1.2035,1.2788,1.3542,1.4295,1.5048,1.5801,1.6552,1.7307,1.8060,1.8813,1.9566,2.0319,2.1072,2.1826,2.2579,2.3332,2.4086,2.4839,2.5592,2.6345,2.7097,2.7851,2.8603,2.9356,3.0110,3.0863,3.1616,3.2370,3.3123,3.3877,3.4629,3.5383,3.6136,3.6888,3.7642,3.8395,3.9148,3.9901,4.0653,4.1407,4.2161,4.2914,4.3667,4.4421,4.5173,4.5926,4.6670,4.7422,4.8175,4.8928,4.9680,5.0433,5.1185,5.1938,5.2691,5.3444,5.4196,5.4948,5.5699,5.6450,5.7199,5.7949,5.8697,5.9444,6.0187,6.0928,6.1663,6.2386,6.3089,6.3744,6.4288,6.4646,6.4872,6.5049,6.5209,6.5363,6.5513,6.5660,6.5807,6.5953,6.6099,6.6244,6.6390,6.6535,6.6681,6.6826,6.6972,6.7117,6.7263,6.7409,6.7555,6.7701,6.7847,6.7994,6.8142,6.8288,6.8439,6.8602,6.8778,6.8966,6.9162,6.9355,6.9547,6.9734,6.9917,7.0093,7.0268,7.0435,7.0453,7.0459,7.0463,7.0466,7.0468,7.0468,7.0469,7.0469,7.0469,7.0469,7.0469,7.0470,7.0470,7.0470,7.0470,7.0470,7.0470,7.0471,7.0471,7.0471,7.0471,7.0471,7.0472,7.0472,7.0472,7.0472,7.0472,7.0472,7.0472,7.0472,7.0473,7.0473,7.0473,7.0473,7.0473,7.0473,7.0473,7.0473,7.0473,7.0474,7.0474,7.0474,7.0474,7.0474,7.0474,7.0474,7.0474,7.0474,7.0475,7.0475,7.0475,7.0475,7.0475,7.0475,7.0475,7.0475,7.0476,7.0476,7.0476,7.0476,7.0476,7.0476,7.0476,7.0476,7.0476,7.0476,7.0476,7.0476,7.0477,7.0477,7.0477,7.0477,7.0477,7.0477,7.0477,7.0477]
cdim=[0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0000,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0001,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0002,0.0003,0.0002,0.0003,0.0003,0.0003,0.0003,0.0003,0.0003,0.0003,0.0003,0.0003,0.0003,0.0004,0.0003,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0004,0.0005,0.0005,0.0005,0.0005,0.0005,0.0005,0.0005,0.0005,0.0005,0.0005,0.0006,0.0006,0.0006,0.0006,0.0006,0.0006,0.0006,0.0006,0.0006,0.0006,0.0007,0.0007,0.0007,0.0007,0.0007,0.0007,0.0008,0.0008,0.0008,0.0008,0.0009,0.0009,0.0009,0.0011,0.0022,0.0050,0.0093,0.0144,0.0198,0.0253,0.0310,0.0366,0.0422,0.0477,0.0531,0.0584,0.0635,0.0677,0.0719,0.0750,0.0731,0.0566,0.0475,0.0444,0.0426,0.0412,0.0402,0.0389,0.0382,0.0374,0.0367,0.0361,0.0356,0.0350,0.0346,0.0341,0.0337,0.0333,0.0329,0.0325,0.0321,0.0317,0.0313,0.0309,0.0305,0.0302,0.0299,0.0296,0.0294,0.0292,0.0290,0.0287,0.0285,0.0283,0.0279,0.0276,0.0274,0.0272,0.0269,0.0268,0.0265,0.0265,0.0264,0.0261,0.0258,0.0257,0.0255,0.0253,0.0252,0.0251,0.0249,0.0247,0.0247,0.0246,0.0244,0.0242,0.0241,0.0241,0.0239,0.0236,0.0234,0.0233,0.0233,0.0231,0.0231,0.0230,0.0228,0.0227,0.0226,0.0225,0.0223,0.0222]

??绘制在加热情况下， 不同工作电源电压对应的稳压输出， 整体上与前面单独稳压二极管的曲线是相同的。 ?绘制出 10V之后的曲线， 这部分稳压特性发生了变化。 ?根据该曲线的斜率， 可以计算出对应的动态电阻。 ?动态电阻为 1.619欧姆， 这比不加热情况下对应的动态电阻变小了。 但比数据手册给定的电阻值1欧姆， 还是打了 60% 左右。

▲ 图1.3.2 输入电压超过10V之后对应的输出电压

四、温度测试

1、没有内部加热

??下面使用热风枪， 给参考电压源加热， 模拟外部温度变化。 LM399H给定的工作电源为 15V。 先不使用它内部的恒温加热电路。 ?测试加热过程中输出电压。 先加热1分钟， 温度可以上升到 130摄氏度， ?然后再撤除热风枪， 使其自然降温。 使用DM3058测量稳压输出。 ?输出电压随着温度增加而发生变化， 在加热过程中， 输出电压上升， 降温过程中， 输出电压下降。 在这个过程中， 电压变化了 6.5mV。

▲ 图1.4.1 使用热风枪加热以及撤销热风枪对应的输出电压变化

#!/usr/local/bin/python
# -*- coding: gbk -*-
#============================================================
# TEST2.PY                     -- by Dr. ZhuoQing 2023-11-22
#
# Note:
#============================================================

from headm import *

import serial
from _ast import Or
from serial.serialutil import SerialException

#------------------------------------------------------------
dm3058 = serial.Serial()
dm3058.baudrate = 115200
dm3058.timeout = 0.05
try:
    dm3058.port = 'COM5'
except:
    printf('Set dm3058 port COM5 error. ')

try:
    dm3058.open()
except serial.serialutil.SerialException:
    printf('Open dm3058 port COM5 error.')
else:
    printf('Open dm3058 port COM5 Ok.')
#------------------------------------------------------------

#------------------------------------------------------------
def dm3058query(cmd):
    dm3058.write(bytes(':%s?\r\n'%cmd, 'gbk'))

    for i in range(200):
        time.sleep(0.01)
        if dm3058.inWaiting() > 0: break

    time.sleep(.02)
    return eval(dm3058.read(dm3058.inWaiting()))

def dm3058dc():
    return dm3058query('MEAS:VOLT:DC')

def dm3058ac():
    return dm3058query('MEAS:VOLT:AC')

def dm3058res():
    return dm3058query('MEAS:RES')

#------------------------------------------------------------

vdim = []
for i in range(120):
    v = dm3058dc()
    time.sleep(1)
    printff(i, v)
    vdim.append(v)
    tspsave('measure', vdim=vdim)

plt.plot(vdim, lw=3)

plt.xlabel("Sample(N)")
plt.ylabel("Voltage(V)")
plt.grid(True)
plt.tight_layout()
plt.show()




printf('\a')



#------------------------------------------------------------
#        END OF FILE : TEST2.PY
#============================================================

2、使用内部加热功能

??将LM399H内部齐纳加热连接到15V的工作电源上。 ?重新测量参考电压源在热风枪加热下对应的电压输出， ?此时， 对应的参考电压源外部的温度从 30到130摄氏度之间变化。 ?输出灭国让人感到惊讶。 可以看到在整个的升温和降温的过程中， ? 输出参考电压变化不超过 0.5mV。 可以看到 LM399H的高性能来自于它内部的恒温功能。

▲ 图1.4.2 带有内不加热情况下温度变化过程

?

※ 总??结 ※

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??本文对于高精度参考电压源 LM399进行了测试。 ?它内部带有齐纳加热二极管， ?能够对稳压二极管进行恒温。?从测量结果来看， 当外部温度从 30摄氏度 变化到 130摄氏度的过程中， 增加了内部恒温之后， 输出电压变化不超过0.5mV。 ?从这里来看， 内部的恒温控制， 是LM399H能够输出高精度参考电压的管脚。 ?但与此对应， 该参考电压源的功耗也非常高。

▲ 图2.1 内部加热对于输出电压的影响

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■ 相关文献链接:

• LM399

● 相关图表链接:

• 图1.2.1 输入电压与输出电压
• 图1.2.2 输入10V之后的输出电压变化
• 图1.3.1 不同电压下的加热电流
• 图1.3.2 输入电压超过10V之后对应的输出电压
• 图1.4.1 使用热风枪加热以及撤销热风枪对应的输出电压变化
• 图1.4.2 带有内不加热情况下温度变化过程
• 图2.1 内部加热对于输出电压的影响