Datasheet LTC3588-1 (Analog Devices) - 10

LTC3588-1
OPERATION
The D0/D1 inputs can be switched while in regulation as
Energy Storage
shown in Figure 3. If VOUT is programmed to a voltage with Harvested energy can be stored on the input capacitor a PGOOD falling threshold above the old VOUT, PGOOD will or the output capacitor. The wide input range takes ad- transition low until the new regulation point is reached. vantage of the fact that energy storage on a capacitor is When VOUT is programmed to a lower voltage, PGOOD proportional to the square of the capacitor voltage. After will remain high through the transition. the output voltage is brought into regulation any excess energy is stored on the input capacitor and its voltage 5 increases. When a load exists at the output the buck can COUT = 100µF, ILOAD = 100mA efficiently transfer energy stored at a high voltage to the D1=D0=0 D1=D0=1 D1=D0=0 4 regulated output. While energy storage at the input utilizes the high voltage at the input, the load current is limited 3 to what the buck converter can supply. If larger loads TAGE (V) need to be serviced the output capacitor can be sized to VOL 2 VOUT support a larger current for some duration. For example, V OUT a current burst could begin when PGOOD goes high and 1 PGOOD = LOGIC1 would continuously deplete the output capacitor until PGOOD went low. 0 0 2 4 6 8 10 12 14 16 18 20 TIME (ms) 35881 F03
Figure 3. PGOOD Operation During D0/D1 Transition
35881fc 10 For more information www.linear.com/LTC3588-1 Document Outline Description Typical Application Absolute Maximum Ratings Pin Configuration Electrical Characteristics Pin Functions Operation Applications Information Typical Application Related Parts