ZHCSG23A March 2017 – February 2018 LM25141-Q1
PRODUCTION DATA.
The open-loop gain is defined as the product of modulator transfer function and feedback transfer function. When plotted on a dB scale, the open-loop gain is shown as the sum of modulator gain and feedback gain.
DC modulator gain is:
The modulator gain plus power stage transfer function with an embedded current loop is show in Equation 50. The Equation 50 includes the sample gain at FSW /2 (ωn), which is caused by sampling effect of current mode control.
where
Because the loop cross over frequency is well below sample gain effects, Equation 50 can be simplified as one pole and a one zero system as shown in Equation 51.
RLOAD is the load resistance
RDCR is the DC resistance on the output inductor which is 8.1 mΩ
RSENSE is the current sense resistance which is 9 mΩ