LT8253/LT8253A

9

Rev. 0

For more information www.analog.com

LT8253A use peak-boost current mode control in buck-

boost region (Figure 4). Switch A is always turned on

for the beginning preset cycle and switch B is always

turned on for the remaining cycle. At the beginning of

every cycle, switches A and C are turned on and the induc-

tor current ramps up. When the inductor current hits the

boost current comparator A4 during (A+C) phase, switch

C is turned off and switch D is turned on for the rest of the

cycle. After preset cycle, switch A is turned off and switch

B is turned on for the rest of the cycle.

A

B

C

D

A+D

A+C

B+D

A+D

A+C

B+D

8253A F04

OPERATION

use peak-boost current mode control in boost region

(Figure 5). Switch A is always on and switch B is always

off. At the beginning of every cycle, switch C is turned

on and the inductor current ramps up. When the induc-

tor current hits the peak boost current threshold com-

during (A+C) phase, switch C is turned off and switch D

is turned on for the rest of the cycle. Switches C and D

will alternate, behaving like a typical synchronous boost

regulator.

A

B

C

100% ON

100% OFF

D

A+D

A+C

A+D

A+C

8253A F05