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Data Sheet | Intel Enpirion Power Solutions: EM2130

Page 21

SMBAlert Pin

The SMBAlert pin is intended to operate using an external pull-up voltage of 3.3V and contains a weak

internal pull-up.

If operating in applications with a lower voltage pull-up voltage, it is recommended that an external low Vf

Schottky diode be placed at the input to localise this voltage.

VPull-Up

SMBAlert

EM2120

Figure 7: SMBAlert Pin Low Voltage Pull-up Option

Table 10: Schottky Diode Options

Description

Manufacturer

P/N

40V, 300mA, Schottky, SOD523

BAT54KFILM

40V, 250mA, Schottky, SOD523

Diode Inc

BAT64T5Q

COMPENSATING THE DIGITAL CONTROL LOOP

To improve the transient performance for a typical point-of-load design, it is common to add output

capacitance to the converter. This moves the output LC resonant frequency lower as capacitance increases

which results in lower bandwidth, lower phase margin, and longer settling times unless the control loop is

compensated for added capacitance.

However, with EM2130 the user does not need to be concerned with, or even understand, the details of

control loop compensation techniques. The default configuration allows users to select from

preconfigured PID control loop settings (known as compensators) through the use of pin-strapping. A

single resistor from the RTUNE pin to AGND informs the EM2130 of the compensator selection.

The selection of the compensator is driven first by the type of output capacitors used, as the ESL and ESR

of different capacitor types demands different PID coefficients to optimize transient deviation and recovery

characteristics. An all ceramic output capacitor design requires a different compensator than a design with

a combination of ceramic and polymer capacitors, i.e. POSCAP. Table 12 shows several output capacitor

part number recommendations.

The five different compensators can then be subdivided into groups of six each whereby the initial

capacitance value in the appropriate compensator can be scaled upwards by multiplication factor M to

match the additional capacitance.

12873

April 10, 2020

Rev I

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