3
dc2117af
DEMO MANUAL DC2117A
Quick start proceDure
freQuency synchronization anD moDe selection
100% Duty
Table 2. Mode Selection and Synchronized Operation Options
CONFIGURATION
JP4
MODE WITH SYNC SIGNAL SUPPLIED TO PLLIN
Forced Continuous Operation
FCM
FCM
Pulse-Skipping Operation
PS
PS
Burst Mode Operation with Adjustable Clamp Level
BURST ADJ
FCM
Burst Mode Operation with Default Clamp
BURST DEFAULT
FCM
Figure 2. Measuring Input or Output Ripple Across Terminals or Directly Across Ceramic Capacitor
Demonstration circuit 2117A’s mode selector allows the
converter to run in forced continuous operation, pulse-
skipping operation, Burst Mode operation or Burst Mode
operation with adjustable clamp level by changing the
position of JP4. To synchronize the DC2117A to an external
clock, apply the sync signal to the PLLIN turret. Depending
upon the JP4 setting, the DC2117A will operate in different
modes. See Table 2 for the detailed description.
+
–
V
OUT
GND
C
OUT
Demonstration circuit 2117A features 100% duty cycle
operation in dropout. Set the JP5 to ON position to activate
this feature. Set JP5 to OFF position disables the internal
charge pump and enables boost refresh, allowing for 99%
duty cycle operation in dropout.