Voltage Margining Adjustment

FEATURES DESCRIPTIONS (CON.)

Power Good

The converter provides an open collector signal called Power Good. This output pin uses positive logic and is open collector. This power good output is able to sink 5mA and set high when the output is within ±10% of output set point.

The power good signal is pulled low when output is not within ±10% of Vout or Enable is OFF.

Current Sink Capability

The NC series converters are able to sink current as well as function as a current source. It is able to sink the full output current at any output voltage up to and including 2.5V. This feature allows the NC series fit into any voltage termination application.

Output voltage margin adjusting can be implemented in the NC modules by connecting a resistor, Rmargin-up, from the Trim pin to the Ground for for margining up the output voltage. Also, the output voltage can be adjusted lower by connecting a resistor, Rmargin-down, from the Trim pin to the voltage source Vt. Figure 30 shows the circuit configuration for output voltage margining adjustment.

NC6A/15A/20A

Output Capacitance

There is no output capacitor on the NC series modules. Hence, an external output capacitor is required for stable operation. For NC15 modules, an external 6.3V/680μF low ESR capacitor (for example, OSCON) is required for stable operation.

It is important to places these low ESR capacitors as close to the load as possible in order to get improved dynamic response and better voltage regulation, especially when the load current is large. Several of these low ESR capacitors could be used together to further lower the ESR.

Please refer to individual datasheet for the maximum allowed start-up load capacitance for each NC series as it is varied between series.

Reflected Ripple Current and Output Ripple and Noise Measurement

The measurement set-up outlined in Figure 31 has been used for both input reflected/ terminal ripple current and output voltage ripple and noise measurements on NC series converters.

Vin

VoutRmargin-down

Trim

Enable

Rmargin-up

Ground Ground

Figure 30: Circuit configuration for output voltage margining

Cs=270μF*1, Ltest=1.4μH, Cin=270μF*1, Cout=680μF *1

Figure 31: Input reflected ripple/ capacitor ripple current and output voltage ripple and noise measurement setup for NC15

Paralleling

NC06/NC15/NC20 converters do not have built-in current sharing (paralleling) ability. Hence, paralleling of multiple NC06/NC15/NC20 converters is not recommended.

NC12S15A_01102008