Data Sheet

LT4423

analog.com

Rev. 0

10 of 18

Figure 13. Automatic Switchover of Load Between a Battery and a Wall Adapter

5V Power Ride-Through

In a diode-OR configuration, multiple diode cathodes are connected in parallel, with the final output voltage set by

the highest cathode potential. The LT4423 is well suited for these applications, with its ability to disable the power

path whenever OUT exceeds IN by approximately 20mV or more, allowing no more than 1µA of reverse current. The

low reverse leakage and the ability to stand-off 28V, and turn off under reverse bias make the LT4423 a high-

performance diode replacement.

Figure 14 demonstrates a diode-OR application with a super-cap charger to provide load power ride-through in the

event of input power loss. The LTC3625 charges two supercapacitors to a sum of 4.8V. Two LT4423s form a diode-OR

circuit between the main 5V input and the supercapacitor 4.8V output. The cathodes of the LT4423s connect to a load

or a downstream voltage regulator. If the main 5V supply is operating, load power is delivered from the 5V supply.

Should the main 5V supply be removed, the 4.8V path turns on, and load power is derived from the supercapacitors.

Figure 14. Riding through Loss of Primary Power Supply

TO LOAD

BATTERY

1.9V TO 28V

R1

4.7kΩ

D1

LNJ237W82RA

C1

4.7µF

D2

B230A

WALL ADAPTER INPUT

GND

IN

OUT

SHDN

STATUS

LT4423

VIN = 5V

COUT

22µF

N/C

PFI

GND

LTC3625

SW1

PROG

VIN

VOUT

EN

CTL

VSEL

SW2

VMID

PFO

PGOOD

4.8V

L1

3.3µH

C2

100F

C3

100F

C1

10µF

R1

287kΩ

R2

100kΩ

R3

143kΩ

TO REGULATOR

GND

IN

OUT

SHDN

STATUS

LT4423

GND

IN

OUT

SHDN

STATUS

LT4423

N/C