Table of Contents
Advertisement
6.4
Output Over Voltage Protection (OVP)
PFH Series modules are equipped with an OVP protection function. The OVP function activates when output voltage is
greater than the OVP trip-point. When the OVP triggers, the module output will shut down either with latch or auto-recovery
depending upon the option code specified. The standard option for PFH Series modules is a latching over voltage
protection.
When the OVP function activates, cut off the input ac line power. Afterwards, verify VBUS voltage has dropped below 10V.
Check for any abnormal conditions. Then, attempt to recover output voltage by cycling input voltage back on.
In addition, the OVP latch can also be reset by turning the module off and then on using either the On/Off pin or via PMBus
command.
The OVP set-point can be changed via PMBus. The OVP setting can only be lowered by via PMBus. The maximum allowed
output voltage is limited by the pre-defined VBUS voltage settings.
Care must be taken to avoid applying higher voltage externally to the output terminals of PFH Series module. Otherwise, it
may cause permanent damage to the module.
6.5
Boost (or VBUS) Over Voltage and Under Voltage Protection (BOVP/BUVP)
PFH Series modules monitor the VBUS voltage to protect it from both over-voltage and under-voltage operation. If a module
reaches these pre-defined protection levels, the module's output will shut down and VBUS will also shutdown. The module
will attempt to auto-restart after the shutdown. The inhibiting time before restart depends on the value of the bulk caps and
bleeder resistor values used.
6.6
Over Current Protection (OCP)
PFH Series modules are equipped with various OCP protection functions including input PFC over-current protection, DC-
DC primary side peak cycle-by-cycle over-current protection, module over-load protection, and short circuit protection. In
normal operating conditions as specified by the specification and derating curves, the OCP protection will not be activated.
The module OCP function triggers when the output current typically exceeds 105% to 140% of maximum rated DC output
current in the specification. To reduce variation, the OCP set-point is temperature compensated, and is calibrated during the
manufacturing test process.
The module's output will automatically recover when the over-load condition or the short circuit is removed.
For modules with non-latching OCP, the module will enter a 2-second hiccup retry sequence once an OCP condition is
detected. The module will try to re-start up to 6 times at 2-second hiccup rate. If the over-load condition remains after the
module tries to re-start up to 6 times, then it will enter a 6-minute hiccup retry sequence. Once the module enters the 6-
minute hiccup mode, it will stay there until the over-load condition is removed, and the module can operate for at least 7
minutes without any OCP alarms. After the 7-minute counter has cleared, the module will revert to the standard 2-second
hiccup timer if a future OCP event is detected.
When the PFH Series module is operated outside the specified input voltage range, the input OCP function may be
activated to protect the module from drawing excessive input current to help guard against damage to the module.
The PFH Series OCP set-point is set to a fixed value, however it can be reduced via PMBus.
NOTE:
(1.) Certain Electronic Loads may have excessive current overshoot which can cause the PFH overcurrent protection
to engage.
(2.) Continuous short circuit or overload conditions are not recommended and might result in power supply over-
heating or damage.
REV 2.8 (March 30, 2020)
TDK-Lambda
PFH500-SERIES
INSTRUCTION MANUAL
18
Advertisement
Table of Contents
