cui.com

date 11/07/2014

│ page 10 of 14

CUI Inc

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

Power Good

The PG pin on the NDM2Z-12 module will assert if the

output of the module is within tolerance of the target

voltage and no fault conditions exist. A PG delay period

is defined as the time from when all conditions within the

module for asserting PG are met to when PG is actually

asserted. By default, PG delay is set equal to the soft-start

ramp time setting. The tolerance, polarity and delay of PG

may be configured via PMBus commands.

Soft-stop Delay and Ramp Times

After CTRL is de-asserted the NDM2Z-12 module utilizes

a pre-ramp delay time before the output starts the ramp-

down process. After the delay period has expired, the

output will begin to ramp towards ground according to the

pre-configured soft-stop ramp time that has been set. It is

recommended to set the soft-start ramp down to a value

greater than 500 μs in order to prevent voltage spikes in

the module input supply rail due the energy stored in the

output capacitors. There will be a delay after the output

voltage has reached ground potential and then the output of

the module will be set to high impedance. Once the output

of the module is high impedance the output voltage may

float to a non-zero value if another source or leakage path

is connected to the output. The soft-stop delay and ramp

times may be configured via PMBus commands.

PMBus commands can be used to set the output of the

NDM2Z-12 module to high impedance as soon as the output

voltage drops below a selectable threshold.

OUTPUT VOLTAGE SETTING

Pin-Strap and Resistor Setting Methods

Using the pin-strap method, the voltage on the VOUT pin

of the NDM2Z-12 module can be set to one of three default

voltages as shown in Table 3. Table 4 lists the available

output voltage settings with a resistor connected between

VSET and PREF.

Table 3: Pin-strap VOUT voltage settings

Table 4: Resistor VOUT voltage settings

SMBus Setting Method

The voltage present at the VOUT pin of the NDM2Z-12

module can be reconfigured using PMBus commands. A

voltage level reconfigured by a PMBus command over-

rides the voltage set by the VSET pin, but cannot be set to

greater than 110% of the voltage set by the VSET pin.

Voltage Tracking

The NDM2Z-12 module includes a feature that allows the

output ramp voltage to track the ramp of a reference

voltage which is applied to the VTRK/PG pin. The voltage

ramp tracking capability can be configured so that member

modules track at either 50% or 100% of the reference

voltage ramp rate. In addition, a member module can be

configured so that the termination voltage either tracks

or ignores perturbations on the reference voltage once it

has stabilized. Tracking at 50% and tracking final voltage

perturbations is intended for DDR memory applications. All

other applications which required voltage tracking should

use 100% tracking and ignore final voltage perturbations.

The reference voltage for tracking must have a target volt-

age which is equal to or greater than the target voltage of

the member modules. The turn-on delay of the reference

voltage must be at least 10 ms greater than that set for the

member modules. In voltage tracking mode, the turn-off

delay of the member modules establishes the time duration

which the member modules will track the reference voltage

after CTRL is de-asserted. The turn-off delay of the member

modules must be at least 5 ms greater than the sum of the

turn-off delay and fall time of the reference voltage.

VSET

VOUT (V)

LOW (< 0.8 V)

0.6

OPEN (N/C)

1.2

HIGH (> 2.0 V) 2.5

RESISTOR (kΩ)

VOUT (V)

RESISTOR (kΩ)

VOUT (V)

10.0

0.60

46.4

1.50

11.0

0.65

51.1

1.60

12.1

0.70

56.2

1.70

13.3

0.75

61.9

1.80

14.7

0.80

68.1

1.90

16.2

0.85

75.0

2.00

17.8

0.90

82.5

2.10

19.6

0.95

90.9

2.20

21.5

1.00

100.0

2.30

23.7

1.05

110.0

2.50

26.1

1.10

121.0

3.00

28.7

1.15

133.0

3.30

31.6

1.20

147.0

4.00

34.8

1.25

162.0

5.00

38.3

1.30

178.0

5.50

42.2

1.40

For more information, please visit the product page.