OKDH-T40-W12-001-C Datasheet, PDF (25/38 Pages) Murata Manufacturing Co., Ltd. – 40A Digital PoL DC-DC Converter Series

OKDx-T/40-W12-xxx-C
40A Digital PoL DC-DC Converter Series
component, such as FPGAs or ASICs. The product family incorporates
synchronous rectifiers, but will not sink current during startup, or turn
off, or whenever a fault shuts down the product in a pre-bias condi-
tion. Pre-bias protection is not offered for current sharing groups that
also have voltage tracking enabled.
Group Communication Bus
The Group Communication Bus, GCB, is used to communicate
between products. This dedicated bus provides the communica-
tion channel between devices for features such as sequencing, fault
spreading, and current sharing. The GCB solves the PMBus data rate
limitation. The GCB pin on all devices in an application should be con-
nected together. A pull-up resistor is required on the common GCB in
order to guarantee the rise time as follows:
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 configurations, 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 configuration settings. When the configurations 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 configured 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 configured 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 config-
ured to do so, and will attempt to re-start in their prescribed order if
configured 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 specification covers use the temperature at position P2 (TP2)
as a reference for specified OTP threshold and some use position P1
(TP1) as a reference for specified OTP threshold. See the Over Tempera-
ture Protection section in the electrical specification for each product.
Products with P1 as reference for OTP:
When TP1 as defined in thermal consideration section exceeds
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approximately 120 °C the product will shut down. The specified OTP
threshold and hysteresis are valid for worst case operation regarding
cooling conditions, input voltage and output voltage. The actually con-
figured 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.
Products with P2 as reference OTP:
When TP2 as defined in thermal consideration section exceeds 120°C
the product will shut down. For products with P2 as a reference for
OTP the configured default value in the controller circuit in position P2
is 120°C.
The OTP threshold, hysteresis, and fault response of the product
can be reconfigured using the PMBus interface. The fault response
can be configured as follows:
1. Initiate a shutdown and attempt to restart an infinite number
of times with a preset delay period between attempts (default
configuration).
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 configuration file which determines the functionality and
performance of the product. It is possible to change the configura-
tion file to optimize certain performance characteristics. In the table
below is a schematic view on how to change different configuration
parameters in order to achieve an optimization towards a wanted
performance.

Increase

No change

Decrease
Config.
parameters
Optimized performance
Maximize
efficiency
Minimize
ripple ampl.
Improve load transient
response
Minimize
idle power loss
Switching
frequency
Control
loop
bandwidth








NLR
threshold
Diode
emulation
(DCM)
Min.
pulse

Enable Disable

Enable
or
disable
Enable or
disable

Disable Disable

Enable Enable
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