cui.com

date 11/07/2014

│ page 10 of 13

CUI Inc

│ MODEL: NDM2Z-12V │ DESCRIPTION: AUTO COMPENSATED, DIGITAL DC-DC POL CONVERTER

Current sharing modules which are also configured to track

a voltage must have all of the VTRK pins tied together.

All of the CTRL pins of the member modules must also be

connected together and driven by a common source. The

rise and fall times of the member modules should be set

between 5 ms and 10 ms to ensure current sharing while

ramping. PMBus commands can be used to configure the

voltage tracking features.

Voltage Margining

The NDM2Z-12 module offers a means to vary the output

voltage higher or lower relative to the nominal voltage

setting. The rate of change of the output voltage during

voltage margining is also configurable. The margin feature

can be reconfigured through PMBus commands.

SWITCHING FREQUENCY AND SYNCHRONIZATION

Switching Frequency

The switching frequency of the NDM2Z-12 module can

be reconfigured by PMBus commands or controlled by an

external clock source connected to the SYNC pin. If the

module is operated at a switching frequency of other than

the factory default setting, the compensation may need to

be adjusted and the ripple, noise, transient response and

efficiency may be affected.

SYNC Auto Detect

The NDM2Z-12 module will automatically check for a clock

signal on the SYNC pin after CTRL is asserted (or applying

input voltage to the module if CTRL is not used). If a clock

signal is present, the module will synchronize to the rising

edge of the external clock. The external clock signal must

be stable and conform to the “RECOMMENDED OPERATING

CONDITIONS” parameters when CTRL is asserted (or

applying input voltage to the module if CTRL is not used).

In the event of a loss of the external clock signal, the

output voltage of the module may show transient overshoot

or undershoot and the module will automatically configure

to switch at a frequency close to the previous incoming

frequency. If no incoming clock signal is present when CTRL

is asserted (or applying input voltage to the module if CTRL

is not used), the module will switch at the frequency set by

the configuration file.

CONTROL LOOP

Adaptive Loop Compensation

The NDM2Z-12 module employs automatic adaptive loop

compensation to increase the performance and stability of

the module over a wide range of conditions. The default

setting configures the module to re-compensate the control

loop every time the output voltage ramps to the regulated

level. PMBus commands can be used to configure when the

module re-compensates the loop.

The user also has the option to manually configure the loop

compensation.

Non-Linear Response (NLR) Settings

The NDM2Z-12 module incorporates a non-linear response

(NLR) loop that decreases the response time and the output

voltage deviation in the event of a sudden output load

current step. This implementation results in a higher

equivalent loop bandwidth than what would be possible

using a traditional linear loop. PMBus commands can be

used to configure the NLR response of the module.

Adaptive Diode Emulation

Please contact CUI technical support regarding the

implementation of adaptive diode emulation.

Adaptive Frequency Control

The NDM2Z-12 module includes adaptive frequency control

to improve conversion efficiency. Adaptive frequency control

is not available for current sharing groups and is not

allowed when the module is placed in auto-detect mode

and a clock source is present on the SYNC pin.

Adaptive frequency control is only available while the

module is operating within adaptive diode emulation mode.

Adaptive frequency control can be enabled and disabled

with PMBus commands.

MULTI-MODULE CONFIGURATION

Output Sequencing

Multiple device sequencing of NDM2Z-12 modules may

be achieved by issuing PMBus commands to assign the

preceding device in the sequencing chain as well as the

device that will follow in the sequencing chain. The CTRL

pins of all devices in a sequencing group must be tied

together and driven high to initiate a sequenced turn-on of

the group. CTRL must be driven low to initiate a sequenced

turnoff of the group.

For more information, please visit the product page.