SC560C datasheet(13/18 Pages) SEMTECH

13 / 18 page

SC560

Applications Information (continued)

The values of the resistors in the voltage divider network

can be calculated using the equation:

REF

OUT

where V

REF = 1V.

The value of R2 should be 100kΩ or

less to ensure noise performance and stability. Values

signi cantly less than 100kΩ will impact the quiescent

current.

Protection Features

The SC560 family provides the following protection

features to ensure that no damage is incurred in the

event of a fault condition:

Under-Voltage Lockout

Over-Temperature Protection

Short-Circuit Protection

Under-Voltage Lockout

The Under-Voltage Lockout (UVLO) circuit protects the

device from operating in an unknown state if the input

voltage supply is too low.

When the V

IN drops below the UVLO threshold, the LDOs

are disabled and PGOOD is held low (SC560C and xed

output variants only). When V

IN is increased above the

hysteresis level, the LDOs are re-enabled into their

previous states, provided EN has remained high. When

powering up with V

IN below the UVLO threshold, the

LDOs remain disabled and PGOOD is held low (SC560C

and xed output variants only).

Over-Temperature Protection

An internal Over-Temperature (OT) protection circuit is

provided that monitors the internal junction temperature.

When the temperature exceeds the OT threshold as

de ned in the Electrical Characteristics section, the OT

protection disables both LDO outputs and holds the

PGOOD signal low. When the junction temperature drops

below the hysteresis level, the LDOs are re-enabled into

their previous states and PGOOD transitions high after a

200ms delay, provided EN has remained high (SC560C

and xed output variants only).

•

Short-Circuit Protection

Each output has short-circuit protection. If the output

current exceeds the current limit, the output voltage will

drop and the output current will be limited until the load

current returns to a speci ed level. If a short-circuit occurs

on the output of LDOA, the output of LDOB will also be

disabled until the fault is removed and the load current

returns to a speci ed level.

Component Selection

A capacitance of 1μF or larger on each output is

recommended to ensure stability. Ceramic capacitors

of type X5R or X7R should be used because of their

low ESR and stable temperature coe cients. It is also

recommended that the input be bypassed with a 2.2μF,

low ESR X5R or X7R capacitor to minimize noise and

improve transient response. Note: Tantalum and Y5V

capacitors are not recommended.

The BYP pin on the SC560D and the xed output versions

must have a minimum of 22nF connected to ground to

meet all noise-sensitive requirements. Increasing the

capacitance to 100nF will further improve PSRR and

output noise.

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