DS_NC12S30A_05222008
8
Over Temperature Protection (OTP)
To provide additional over-temperature protection in a
fault condition, the unit is equipped with a non-latching
thermal shutdown circuit. The shutdown circuit engages
when the temperature of monitored component exceeds
approximately 130℃. The unit will cycle on and off while
the fault condition exists. The unit will recover from
shutdown when the cause of the over temperature
condition is removed.
Over Voltage Protection (OVP)
The converter will shut down when an output over voltage
is detected. Once the OVP condition is detected, the
controller will stop all PWM outputs and will turn on
low-side MOSFET driver to prevent any damage to load.
Current Sharing (optional)
The parallel operation of multiple converters is available
with the NC30/NC40 (option code B). The converters will
current share to be within +/- 10% of each other. In
addition to connect the I-Share pin together for the current
sharing operation, the remote sense lines of the
paralleled units must be connected at the same point for
proper operation. Also, units are intended to be turned
on/enabled at the same time. Hot plugging is not
recommended. The current sharing diagram show in
Figure 30.
C30A/40A
0
HARE
HARE
out
SENSE
ROUND
ROUND
RIM
C30A/40A
Cout
0
RIM
Cout
SENSE
OAD
ENSE
ENSE
out
Figure 30: NC30/NC40 Current Sharing Diagram
FEATURES DESCRIPTIONS (CON.)
Input Under-Voltage Lockout
The input under-voltage lockout prevents the converter
from being damaged while operating when the input
voltage is too low. The lockout occurs between 7.7V to
8.6V.
Over-Current and Short-Circuit Protection
The NC series modules have non-latching over-current
and short-circuit protection circuitry. When over current
condition occurs, the module goes into the non-latching
hiccup mode. When the over-current condition is
removed, the module will resume normal operation.
An over current condition is detected by measuring the
voltage drop across the high-side MOSFET. The voltage
drop across the MOSFET is also a function of the
MOSFET’s Rds(on). Rds(on) is affected by temperature,
therefore ambient temperature will affect the current limit
inception point.
The unit will not be damaged in an over current condition
because it will be protected by the over temperature
protection.
Remote Sense
The NC30/NC40 provide Vo remote sensing to achieve
proper regulation at the load points and reduce effects
of distribution losses on output line. In the event of an
open remote sense line, the module shall maintain local
sense regulation through an internal resistor. The
module shall correct for a total of 0.4V of loss. The
remote sense connects as shown in Figures 29.
o
-SENSE
GROUND
Contact and Distribution
Losses
VIN
+SENSE
GROUND
Vo
o
R
load
Figure 29: Circuit configuration for remote sense
