Protection IC Datasheet

© 2024 Littelfuse, Inc.

Specifications are subject to change without notice.

Revised: JC. 08/12/24

LS0502SCD33

Super Capacitor Protection IC for Backup Power Applications

7

Description

For applications which require backup power in harsh environment, Lithium-Ion battery cannot be used due to limited temperature range.

Super capacitor with wide operating temperature range and high power/energy density, provides a safe and compact solution. For many

systems, the high operating voltage (>3 V) requires a power management system for super capacitor with two stacked cells or use a

BOOST converter with inductor. Many systems also require long standby time (weeks of time), this need can only be realized with very

low quiescent current.

LS0502SCD33 provides a flexible, integrated and compact storage capacitor or capacitor bank backup solution with extensive protection

function to ensure a safe, efficient, compact and low cost solution for these applications. LS0502SCD33 integrates input overvoltage/

current protection to prevent damage to following system. It also integrates an ideal diode for reverse blocking when input voltage is lost.

LS0502SCD33 integrates a linear charger to charge super capacitor with as high as 350 mA current to achieve fast and safe charging. The

charging devices also act as power path control switch. When input power is lost, this switch can be turned on to keep the system rail

stable in backup mode. In backup mode, quiescent current draw from super capacitor is only 2.5 μA. This ensures very long standby time

of the system with low capacitance super capacitor.

LS0502SCD33 integrates a programmable Input voltage monitor. When input voltage drops below certain voltage set by resistor divider

connected to PFB pin, a flag signal on PFLTB will inform the following system about the event so that preventative actions can be taken

like process and save data in DRAM. With 2 super capacitors in stack, LS0502SCD33 integrates cell balancing function. During charging

mode, voltage between two stack capacitor is compared with half of total capacitor voltage. Current is diverted to keep these two voltages

close to each other. LS0502SCD33 also integrates cell monitoring and protection circuit. This circuit monitors voltage for each capacitor.

During charging mode, if any capacitor voltage reaches 2.65 V, charging will be stopped until this fault is gone. Same way, during discharge

mode, if any of the capacitor voltage drop below ground, discharging will be stopped to protect the capacitors.

Figure 12 : Charger Mode VSYS Short

Figure 13 : Charger Mode VSYS Short Recovery

VCAP

VSYS

1 V/div

1 V/div

VIN = 5 V

10 ms/div

ICHG= 0.3 A

PFLTB

ISYS = 0 A~short

IIN

1 V/div

1 A/div

VCAP

VSYS

1 V/div

1 V/div

VIN = 5 V

10 ms/div

ICHG = 0.3 A

ISYS = short~0 A

PFLTB

IIN

1 V/div

1 A/div

Figure 14 : Discharge Mode VSYS Short

Figure 15 : Discharge Mode VSYS Short Recovery

VCAP

VSYS

1 V/div

1 V/div

4 ms/div

ISYS = short~0 A

VCAP

VSYS

1 V/div

1 V/div

ISYS = 0 A~short

1 ms/div