Datasheet

Products with P2 as reference OTP:
When TP2 as defi ned in thermal consideration section exceeds 120°C
the product will shut down. For products with P2 as a reference for
OTP the confi gured default value in the controller circuit in position P2
is 120°C.
The OTP threshold, hysteresis, and fault response of the product
can be reconfi gured using the PMBus interface. The fault response
can be confi gured as follows:
1. Initiate a shutdown and attempt to restart an infi nite number
of times with a preset delay period between attempts (default
confi guration).
2. Initiate a shutdown and attempt to restart a preset number of
times with a preset delay period between attempts.
3. Continue operating for a given delay period, followed by shutdown
if the fault still exists.
4. Continue operating through the fault (this could result in perma-
nent damage to the power supply).
5. Initiate an immediate shutdown.
Optimization examples
This product is designed with a digital control circuit. The control
circuit uses a confi guration fi le which determines the functionality and
performance of the product. It is possible to change the confi gura-
tion fi le to optimize certain performance characteristics. In the table
below is a schematic view on how to change different confi guration
parameters in order to achieve an optimization towards a wanted
performance.

Increase

No change

Decrease
Config.
parameters
Switching
frequency
Control
loop
bandwidth
NLR
threshold
Diode
emulation
(DCM)
Min.
pulse
Optimized performance
Maximize
effi ciency

Enable Disable
Minimize
ripple ampl.

Enable
or
disable
Enable or
disable
Improve load transient
response

Disable Disable
Minimize
idle power loss

Enable Enable
Note 1: The following table, graphs, and waveforms are only examples and valid for
OKDX-T/50-W12-001-C.
Note 2: In the following table and graphs, the worst-case scenario (load step 37.5-12.5
A) has been considered for load transient.
Eq. 5.  = R
GCB
C
GCB
≤ 1µs,
where R
GCB
is the pull up resistor value and C
GCB
is the bus loading.
The pull-up resistor should be tied to an external supply voltage in
range from 3.3 to 5 V, which should be present priorµ to or during
power-up.
If exploring untested compensation or deadtime confi gurations, it is
recommended that 27 Ω series resistors are placed between the GCB
pin of each product and the common GCB connection. This will avoid
propagation of faults between products potentially caused by hazard-
ous confi guration settings. When the confi gurations of the products
are settled the series resistors can be removed.
The GCB is an internal bus, such that it is only connected across
the modules and not the PMBus system host. GCB addresses are
assigned on a rail level, i.e. modules within the same current sharing
group share the same GCB address. Addressing rails across the GCB
is done with a 5 bit GCB ID, yielding a theoretical total of 32 rails that
can be shared with a single GCB bus.
Fault spreading
The product can be confi gured to broadcast a fault event over the
GCB bus to the other devices in the group. When a non-destructive
fault occurs and the device is confi gured to shut down on a fault, the
device will shut down and broadcast the fault event over the GCB bus.
The other devices on the GCB bus will shut down together if confi g-
ured to do so, and will attempt to re-start in their prescribed order if
confi gured to do so.
Over Temperature Protection (OTP)
The products are protected from thermal overload by an internal over
temperature shutdown function in the controller circuit N1, located at
position P2 (see section Thermal Consideration). Some of the products
that this specifi cation covers use the temperature at position P2 (TP2)
as a reference for specifi ed OTP threshold and some use position
P1 (TP1) as a reference for specifi ed OTP threshold. See the Over
Temperature Protection section in the electrical specifi cation for each
product.
Products with P1 as reference for OTP:
When TP1 as defi ned in thermal consideration section exceeds
approximately 120 °C the product will shut down. The specifi ed OTP
threshold and hysteresis are valid for worst case operation regarding
cooling conditions, input voltage and output voltage. The actually con-
fi gured default value in the controller circuit in position P2 is 110 °C,
but at worst case operation the temperature is approximately 10 °C
higher at position P1. At light load the temperature is approximately
the same in position P1 and P2. This means the OTP threshold and
hysteresis will be lower at light load conditions when P1 is used as a
reference for OTP.
OKDx-T/50-W12-C
50A Digital PoL DC-DC Converter Series
MDC_OKDx-T/50-W12-C.A04 Page 26 of 41
www.murata-ps.com/support