MIC2132 datasheet(26/48 Pages) MICROCHIP

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MIC2132

DS20006654B-page 26

 2022 Microchip Technology Inc. and its subsidiaries

FIGURE 4-12:

EN Pin Sequencing.

When the EN pin voltage is below the lower EN thresh-

old, the MIC2132 goes into Shutdown mode. When in

Shutdown mode, the MIC2132 stops switching and all

internal control circuitry switches off to reduce the quies-

cent current. The EN pin, along with the PG pin, can be

used for sequencing multiple MIC2132 devices. It is

recommended to power up VIN before the EN signal.

4.5.9

ADAPTIVE VOLTAGE POSITIONING

(AVP), ALSO KNOWN AS DROOP

FUNCTION (RECOMMENDED FOR

CCM ONLY)

In some high-current applications, a requirement on a

precisely controlled output impedance is imposed. This

dependence of output voltage on load current is often

termed, “droop”, “load line” regulation, or Adaptive

Voltage Positioning (AVP).

The basic functionality of the AVP function is to achieve

a controlled output resistance for the buck regulator, so

that at 0A load, the output is +Ɛ% higher than the nom-

inal voltage and at maximum load, the output is -Ɛ%

related to the nominal output value, as shown in

Figure 4-13.

FIGURE 4-13:

AVP Ideal Output Resistive

Characteristic.

It is necessary to achieve the resistive characteristic

above over the full frequency range of output loads.

FIGURE 4-14:

VOUT Load Transient Error

without AVP/DROOP.

FIGURE 4-15:

VOUT Load Transient Error

with AVP/DROOP.

Figure 4-14 and Figure 4-15 explain how the AVP

design window of ±Ɛ can be used to reduce the amount

of the output capacitor necessary to sustain the load

transient. Alternatively, the AVP can be used to improve

the error of the load transient if it is decided to keep the

same output capacitor.

The DROOP pin is an analog output, which provides a

voltage proportional with the output current in CCM,

according to the formula in Equation 4-20.

EQUATION 4-20:

PVDD/VDD

VDD UVLO

Bias ready

VOUT

Bypass

VIN

VOUT

OUTPUT CURRENT (A)

IOUT(MAX)

ΔVOUT = VOUT × 2ε

VOUT(DC)

Where:

VCSH = Voltage at CSH Pin in CCM

RSENSE = Current Sensing Resistance

IL = Inductor Current per Phase

VDROOP = VCSH – 1.2V = 8 × RSENSE × IL

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