JAJSGV6 January 2019 TPS54560B
PRODUCTION DATA.
Figure 28 shows an equivalent model for the TPS54560B control loop that can be simulated to check the frequency response and dynamic load response. The error amplifier is a transconductance amplifier with a gmEA of 350 μA/V. The error amplifier can be modeled using an ideal voltage-controlled current source. The resistor Ro and capacitor Co model the open-loop gain and frequency response of the amplifier. The 1-mV ac voltage source between the nodes a and b effectively breaks the control loop for the frequency response measurements. Plotting c/a provides the small signal response of the frequency compensation. Plotting a/b provides the small signal response of the overall loop. The dynamic loop response can be evaluated by replacing RL with a current source with the appropriate load-step amplitude and step rate in a time-domain analysis. This equivalent model is only valid for CCM operation.