SC560 SEMTECH [Semtech Corporation], SC560 Datasheet - Page 11

• Manufacturer Part Number: SC560
• Description: Dual Output Low Noise LDO Linear Regulator
• Manufacturer: SEMTECH [Semtech Corporation]

Applications Information (continued)
The values of the resistors in the voltage divider network
can be calculated using the equation:
where V
pins of each LDO is only a few μA, the value of R2 can be
as high as 100kΩ without aff ecting accuracy. The value
of R2 should be between 100kΩ and 200kΩ to maintain
quiescent current of less than 100μA.
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
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
are disabled and PGOOD is held low (SC560C and fi xed
output variants only). When V
hysteresis level, the LDOs are re-enabled into their
previous states, provided EN has remained high. When
powering up with V
LDOs remain disabled and PGOOD is held low (SC560C
and fi xed output variants only).
•
•
•
V
OUT
Under-Voltage Lockout
Over-Temperature Protection
Short-Circuit Protection
REF
V
= 1V. Since the bias current into the feedback
IN
REF
drops below the UVLO threshold, the LDOs
R
1
R
2
R
IN
2
below the UVLO threshold, the
IN
is increased above the
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
defi 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 fi 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 specifi 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 specifi 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 coeffi 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 fi 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.
SC560
11