- 您现在的位置：买卖IC网 > PDF目录44546 > LM25066PSQX (NATIONAL SEMICONDUCTOR CORP) POWER SUPPLY SUPPORT CKT, QCC24 PDF资料下载
参数资料
| 型号： | LM25066PSQX |
| 厂商： | NATIONAL SEMICONDUCTOR CORP |
| 元件分类： | 电源管理 |
| 英文描述： | POWER SUPPLY SUPPORT CKT, QCC24 |
| 封装： | LLP-24 |
| 文件页数： | 37/48页 |
| 文件大小： | 1456K |
| 代理商： | LM25066PSQX |
第1页第2页第3页第4页第5页第6页第7页第8页第9页第10页第11页第12页第13页第14页第15页第16页第17页第18页第19页第20页第21页第22页第23页第24页第25页第26页第27页第28页第29页第30页第31页第32页第33页第34页第35页第36页当前第37页第38页第39页第40页第41页第42页第43页第44页第45页第46页第47页第48页
Determining Telemetry Coefficients
Empirically with Linear Fit
The coefficients for telemetry measurements and warning
thresholds presented in Table 41 are adequate for the ma-
jority of applications. Current and power coefficients must be
calculated per application as they are dependent on the value
of the sense resistor, R
S, used. Table 42 provides the equa-
tions necessary for calculating the current and power coeffi-
cients for the general case. The small signal nature of the
current measurement make it and the power measurement
more susceptible to PCB parasitics than other telemetry
channels. This may cause slight variations in the optimum
coefficients (m, b, R) for converting from Direct Format digital
values to real-world values (e.g. Amps and Watts). The opti-
mum coefficients can be determined empirically for a specific
application and PCB layout using two or more measurements
of the telemetry channel of interest. The current coefficients
can be determined using the following method:
1.
While the LM25066 is in normal operation, measure the
voltage across the sense resistor using kelvin test points
and a high accuracy DVM while controlling the load
current. Record the integer value returned by the
READ_AVG_IIN command (with the
SAMPLES_FOR_AVG set to a value greater than 0) for
two or more voltages across the sense resistor. For best
results, the individual READ_AVG_IIN measurements
should span nearly the full scale range of the current (for
example, voltage across R
S of 5 mV and 20 mV).
2.
Convert the measured voltages to currents by dividing
them by the value of R
S. For best accuracy, the value of
R
S should be measured. Table 43 assumes a sense
resistor value of 5 m
.
TABLE 43. Measurements for linear fit determination of
current coefficients:
Measured voltage
across
R
S (V)
Measured Current
(A)
READ_AVG_IIN
(integer value)
0.005
1
648
0.01
2
1331
0.02
4
2698
3.
Using the spreadsheet or math program of your choice,
determine the slope and the y-intercept values returned
by the READ_AVG_IIN command versus the measured
current. For the data shown in Table 43:
READ_AVG_IIN value = slope x (Measured Current) +
(y-intercept)
slope = 683.4
y-intercept = -35.5
4.
To determine the ‘m’ coefficient, simply shift the decimal
point of the calculated slope to arrive at an integer with a
suitable number of significant digits for accuracy
(typically 4) while staying with the range of -32768 to
+32767. This shift in the decimal point equates to the
‘R’ coefficient. For the slope value shown above, the
decimal point would be shifted to the right once hence
R
= -1.
5.
Once the ‘R’ coefficient has been determined, the ‘b’
coefficient is found by multiplying the y-intercept by
10-R. In this case the value of b = -355.
Calculated Current Coefficients:
m
= 6834
b
= -355
R
= -1
where:
X:
the calculated "real world" value (volts, amps, watts, tem-
perature)
m:
the slope coefficient, a the two byte two's complement in-
teger
Y:
a two byte, two's complement integer received from device
b:
the offset, a two byte two's complement integer
R:
the exponent, a one byte two's complement integer
The above procedure can be repeated to determine the co-
efficients of any telemetry channel simply by substituting
measured current for some other parameter (e.g. power, volt-
age, etc.).
Writing Telemetry Data
There are several locations that will require writing data if their
optional usage is desired. Use the same coefficients previ-
ously calculated for your application and apply them using this
method as prescribed by the PMBus revision section 7.2.2
"Sending a Value"
Y = (mX + b) x 10R
where:
X:
the calculated "real world" value (volts, amps, watts, tem-
perature)
m:
the slope coefficient, a two byte two's complement integer
Y:
a two byte two's complement integer received from device
b:
the offset, a two byte two's complement integer
R:
the exponent, a one byte two's complement integer
www.national.com
42
LM25066
相关PDF资料 |
PDF描述 |
|---|---|
| LM25066PSQ | POWER SUPPLY SUPPORT CKT, QCC24 |
| LM25574Q0MT | SWITCHING REGULATOR, PDSO16 |
| LM25574Q0MTX | SWITCHING REGULATOR, PDSO16 |
| LM25576Q0MH | SWITCHING REGULATOR, PDSO20 |
| LM2574HVADJMWC | 1.8 A SWITCHING REGULATOR, 63 kHz SWITCHING FREQ-MAX, UUC |
相关代理商/技术参数 |
参数描述 |
|---|---|
| LM25066PSQX/NOPB | 功能描述:热插拔功率分布 RoHS:否 制造商:Texas Instruments 产品:Controllers & Switches 电流限制: 电源电压-最大:7 V 电源电压-最小:- 0.3 V 工作温度范围: 功率耗散: 安装风格:SMD/SMT 封装 / 箱体:MSOP-8 封装:Tube |
| LM25069 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Positive Low Voltage Power Limiting Hot Swap Controller |
| LM25069MM-2EVAL | 功能描述:BOARD EVALUATION LM25069 RoHS:是 类别:编程器，开发系统 >> 评估演示板和套件 系列:- 标准包装:1 系列:PCI Express® (PCIe) 主要目的:接口，收发器，PCI Express 嵌入式:- 已用 IC / 零件:DS80PCI800 主要属性:- 次要属性:- 已供物品:板 |
| LM25069MM-2EVAL/NOPB | 功能描述:电源管理IC开发工具 LM25069MM-2 Eval Brd 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 |
| LM25069PMM-1 | 制造商:NSC 制造商全称:National Semiconductor 功能描述:Positive Low Voltage Power Limiting Hot Swap Controller |
发布紧急采购，3分钟左右您将得到回复。