SC630

11

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 SC630 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. 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 parallel 10μF capacitors may be

used in place of each 22μF.

For applications with load currents below 100 mA, the

bucket capacitors may be reduced to 1μF and the input

and output capacitors may be reduced to 10μF. The fol-

lowing table lists recommended capacitor values. Note

that the smallest available capacitor packages have very

poor DC voltage characteristics. 0402 and 0603 size

capacitors may be as low as 50% of rated value

at 3.3V.

Applications Information (continued)

The following capacitors are recommended for best per-

formance. Use only X5R ceramic with a voltage rating of

6.3V or higher.

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

IN

, C

OUT

10

0805

Typical performance is similar to

the 22uF if 0805 capacitor size is

used, due to the weaker DC volt-

age coefficient of the 22uF 0805.

C

IN

, C

OUT

10

0603

Typical output V

PP

as high as

75mV in boosting charge pump

modes

Typical input ripple as high as

175mV in boosting charge pump

modes

For a lower profile design, two

10uF 0603’s may be substituted

in place of one 10uF or 22uF

0805. Two are needed, due to the

weaker DC voltage coefficient of

the 0603 package size.

C

BUCKET

2.2

0603

Required for the full rated output

current

C

BUCKET

2.2

0402

Useful for load current up to

300mA

C

BUCKET

1.0

0402

Useful for load current up to

100mA

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.