TPS73625 chip test based on acceleration technology ST2500 (3)

Table of contents

3. TPS73625 chip linear adjustment rate test

1. Test principle

2. Test schematic diagram

3. Test steps

4. Test code

5. Test results

3. TPS73625 chip linear adjustment rate test

1. Test principle

TPS736xx is a linear regulator with N-MOS structure, and its working range is shown in the figure. When VN-VOUT>VO, the voltage regulator works in the saturation region at this time. When the output load (IOUT) is fixed, VN is changed within the input voltage range, and the output of the voltage regulator is theoretically a fixed value. However, in reality, due to technological reasons, the output of the voltage regulator changes with the input voltage, which will have a certain impact. We use the linear adjustment rate to characterize the ability of the input voltage of the voltage regulator to change and the output voltage to remain constant. The smaller the linear adjustment rate of the voltage regulator, the smaller the impact of input voltage changes on the output voltage, and the better the performance of the voltage regulator. Figure 7.13 shows the relationship between output voltage and input voltage.

Taking TPS73625 as an example, according to the requirements of the chip manual (Vo (typical value) + 0.5V VN 5.5V), we can determine that 3V< VN < 5.5V. The test procedure is, VIN is 3V, measure the VOUT output as Vo; VIN is 5.5V, measure the VOUT output as Vmax; V= 5.5V - 3V = 2.5V.

        AVine: LDO linear adjustment rate
        Vo: LDO nominal output voltage
        Vmax: LDO maximum input voltage
        AV: The difference between the maximum and minimum output voltage when the LDO input changes from Vo to Vmax

2. Test schematic diagram

3. Test steps

(1) Close K3, connect OUT pin to 250Ω load

(2) Use PPMU resources to apply 2V to the EN pin

(3) Use DPS resource to apply 3V voltage to IN pin

(4) Use the "FNMV" working mode of the BPMU to measure the OUT pin voltage Uo1

(5) Use DPS resources to apply 5.5V voltage to the IN pin

(6) Use the BPMU resource to measure the OUT pin voltage Uo2

(7) Calculate the linear adjustment rate according to the formula

(8) Divide the result into BIN and reset the hardware

4. Test code

USER_CODE void LNR_TEST() {
	TEST_BEGIN

	// TODO Edit your code here
	//定义变量存储读取结果
	vector<ST_MEAS_RESULT> stMeasValue,stMeasValue_LNR;

	//闭合K3，选择250Ω负载
	cbit.Signal("K3").SetOn();
	sys.DelayUs(10000);

	//使用PPMU资源向EN引脚施加2V电压
	ppmu.Signal("EN").SetMode("FVMI").VoltForce(2.0).CurrRange(40e-3).Execute();

	//使用DPS资源向IN引脚施加3V电压
	dps.Signal("IND").SetMode("FVMI").VoltForce(3.0).CurrRange(0.5).CurrClamp(0.5, -0.5).Execute();

	//使用BPMU资源测量OUT引脚输出电压UO1
	bpmu.Signal("OUTB").SetMode("FNMV").Execute();
	sys.DelayUs(30000);
	bpmu.Signal("OUTB").Measure(stMeasValue);

	//使用DPS资源向IN引脚施加5.5V电压
	dps.Signal("IND").SetMode("FVMI").VoltForce(5.5).CurrRange(0.5).CurrClamp(0.5, -0.5).Execute();

	//使用BPMU资源测量OUT引脚输出电压值UO2
	bpmu.Signal("OUTB").SetMode("FNMV").Execute();
	sys.DelayUs(25000);
	bpmu.Signal("OUTB").Measure(stMeasValue_LNR);

	//计算线性调整率
	stMeasValue_LNR[0].dbValue = (stMeasValue_LNR[0].dbValue-stMeasValue[0].dbValue)/(stMeasValue[0].dbValue*2.5)*100;

	//进行分BIN操作
	binObj.CheckResultAndBin(0, stMeasValue_LNR, 1);


	//释放PPMU,DPS资源
	ppmu.Signal("EN").Connect();
	dps.Signal("IND").Connect();

	//复位
	ppmu.Signal("EN").SetMode("FVMI").VoltForce(0.0).Execute();
	ppmu.Signal("EN").SetMode("FNMV").Execute();

	dps.Signal("IND").SetMode("FVMI").VoltForce(0.0).Execute();
	dps.Signal("IND").SetMode("FNMV").Execute();

	//断开K3
	cbit.Signal("K3").SetOff();
	sys.DelayUs(8000);

	TEST_ERROR
	binObj.HandlerException(0);
	TEST_END
}