LP3202 Datasheet, PDF (10/11 Pages) Lowpower Semiconductor inc – 1.5MHz, 650mA, High Efficiency Synchronous PWM Step-Down DC/DC Convert

LP3202
Checking Transient Response
The regulator loop response can be checked by looking at the load transient response. Switching
regulators take several cycles to respond to a step in load current. When a load step occurs, VOUT
immediately shifts by an amount equal to ∆ILOAD (ESR), where ESR is the effective series resistance of COUT.
∆ILOAD also begins to charge or discharge COUT generating a feedback error signal used by the regulator to
return VOUT to its steady-state value. During this recovery time, VOUT can be monitored for overshoot or
ringing that would indicate a stability problem.
Layout Considerations
Follow the PCB layout guidelines for optimal performance of LP3202.
For the main current paths as indicated in bold lines, keep their traces short and wide.
Put the input capacitor as close as possible to the device pins (VIN and GND).
LX node is with high frequency voltage swing and should be kept small area. Keep analog components
away from LX node to prevent stray capacitive noise pick-up.
Connect feedback network behind the output capacitors. Keep the loop area small. Place the feedback
components near the LP3202.
Connect all analog grounds to a command node and then connect the command node to the power
ground behind the output capacitors.
LP3202-01 datasheet Oct.-2006
10 -10