SC560
13
Applications Information (continued)
The values of the resistors in the voltage divider network
can be calculated using the equation:
2
21
REFOUT
R
RR
VV
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 c ients. 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.
