SABRE-LL-I datasheet(43/141 Pages) STMICROELECTRONICS

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SABRE-LL-I

Switching regulator controller

43/141

Figure 10.

Switching regulator controller functional blocks

13.2

Pulse skipping operation

Pulse skipping strategy has already been explained on main switching regulator section.

This regulator has 4 possible PWM duty cycles that can be changed writing in the

SelSwCtrPWM bits in the SwCtrCfg register using SPI.

Adjustable duty cycles can be changed using a metal layer change in order to adapt it to

customer system. The only limitation is that all regulators share the same duty cycle bus, so

any modification must consider all regulators needed duty cycles.

Vout

Vsupply

Driver

Control

Logic

CurrentSense

Charge pump Voltage

Voltage

Loop Control

VFBRef

Under voltage

Threshold

Filter

From Central Logic

Regulator Freq

To Central Logic

undervoltage flag

Rsense

VSWDRV_gate

N-CH Fet

Vref = 3 V

Vref=0.8V

SelFBRef[1:0]

Uv Threshold 1

SelFBRef

Uv Threshold 2

Vref = 3V

Vref=0.8V

VSWDRV FB

VSWDRV SW

VSWDRW_sns

Table 23.

Switching regulator controller PWM specification

SwCtrCfg register

Duty cycle value

Comments

SelSwCtrPWM[1:0]

Typical

12%

22.5%

Default state

58%

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