SC631

11

Over-Current Protection

Over-current protection is provided to limit the output

current. When V

OUT

is greater than 2V, OCP limits the output

to 1A typical. The 2V threshold allows the device to

recover from excessive voltage droop during an over-

current event.

Short-Circuit Current Protection

Short-circuit current protection is provided to limit the

current that can be sourced when the output is shorted to

ground. When a short circuit forces V

OUT

to drop below 2V,

the SCCP detects the condition and limits the output

current to 600mA (typical).

Over-Temperature Protection

The over-temperature circuit helps prevent the device

from overheating and experiencing a catastrophic failure.

When the junction temperature exceeds 165°C, the device

is disabled. It remains disabled until the junction tempera-

ture drops below this threshold. Hysteresis is included

that prevents the device from re-enabling until the junc-

tion temperature is reduced by 20°C.

Capacitor Selection

The SC631 is designed to use low-ESR ceramic capacitors

for the input and output bypass capacitors as well as the

charge pump bucket capacitors. Ideal performance is

achieved when the bucket capacitors are exactly equal.

The value of input and output decoupling capacitors will

vary with system requirements. For best ripple perfor-

mance C

IN

and C

OUT

are normally 22μF and the bucket

capacitors C

1

and C

2

are 2.2μF. For low profile designs, two

10μF capacitors may be used in place of each 22μF.

Applications Information (continued)

When selecting capacitors for the application, the DC

voltage characteristic of the capacitor should be consid-

ered. The value of capacitance at the DC operating voltage

may be considerably lower than the rated value. The fol-

lowing table lists recommended capacitor values which

have been chosen to minimize the impact of this

limitation.

Table 1 — Recommended Capacitors

Capacitor

Value

μF

Case

Size

Notes

C

IN

, C

OUT

22

0805

Typical output V

PP

≤ 20mV in all

charge pump modes

Typical input ripple ≤ 100mV in all

charge pump modes

C

BUCKET

2.2

0603

Required for the full rated output

current

C

BUCKET

2.2

0402

Useful for load current up to

300mA

NOTE: Use only X5R type capacitors, with a 6.3V rating or higher

The highest capacitance values in the smallest package

sizes tend to have poor DC voltage characteristics. The

highest value 0402 size capacitor retains as little as 35% of

its rated value at 5VDC. The same value chosen in the next

larger package size (0603) retains about 60% of its rated

value at 5VDC.