How to Measure LDO's Output Voltage

Measure Output Voltage on SIMetrix

  

LDO model packet and test circuit for output voltage 

 

Fig 1. LDO model packet and test circuit for output voltage

 Objectiv

To see the actual value of output voltage V_OUT(E) compared to the set output voltage V_OUT(S).

• V_OUT(E) is actual output voltage 
• V_OUT(S) is set output voltage

 

Condition

• V_OUT(S) = 1.5V

• V_IN = V_OUT(S)+ 1.5V = 3V (for this case, because our LDO model has higher dropout)

• I_OUT = 30mA the R_L= V_OUT(S) / I_OUT = 50Ω

Procedure

Sweep V_IN from 0 to 5V and probe V_OUT and I_OUT.

Fig 2. Choose analysis voltage

 Result

 

While input voltage (VDD) = 3V then output voltage V_{OUT(E) = 1.497V and IOUT = 29.94mA}  

 

Fig 3. Graph of output voltage and output current