RT3612EB datasheet(26/47 Pages) RICHTEK

26 / 47 page

RT3612EB

DS3612EB-02 December 2019

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Loadline Setting (RLL)

An output voltage loadline (Adaptive Voltage Positioning)

are specified in CPU VR for power saving and output

capacitance reduction. The characteristic of loadline is

that the output voltage decreases by an amount proportional

to the increasing loading current, i.e. the slope between

output voltage and loading current (RLL) is shown in Figure

9. Figure 10 shows how the voltage and current loop

parameters of RT3612EB achieve loadline. The detailed

equation is described as below :

IMON EQ

CSx

EA2

EA1

Current Loop Gain

DCR

Voltage Loop Gain





Ai is current gain. REA2 / REA1 is defined as ERROR AMP

gain. In order to have better transient performance, the

ERROR AMP gain is suggested to be within 2.2 to 3.6

when ICCMAX >= 45A and within 2.2 to 5 when ICCMAX

< 45A. RLL can be programmed by Ai and REA2 / REA1. Ai

can be selected by PIN-SETTING of Ai[1:0] as listed in

Table 8.

Figure 9. Load-Line (Droop)

VCORE

VID

RLL x ICCMAX

Loadline=-RLL

ICCMAX

Current

Table 8. PIN-SETTING of Ai[1:0]

Ai[1:0]

Current Gain Setting

0.125

0.25

0.375

0.5

Figure 8. Total Current Sense Method

Total Current Sense/ICCMAX Setting/Current

Monitoring

To compensate DCR positive temperature coefficient,

conventional current sense method needs an NTC resistor

for per phase current loop. The RT3612EB adopts a

patented total current sense method that requires only

one NTC resistor for thermal compensation. The NTC

resistor is designed within IMON resistor network on IMON

pin. It is suggested to be placed near the inductor of the

first phase. Figure 8 shows the configuration. All phase

current signals are gathered to IMON pin and converted

to a voltage signal VIMON by RIMON,EQ based on VREF06

pin. VREF06 pin provides 0.6V voltage source (as

presented as VVREF06) while normal operation. The

relationship between VIMON and inductor current ILx is :



IMON

VREF06

L1 L2

IMON EQ

CSx

DCR

I +I





VIMON

− VVREF06 is proportional to output current. VIMON −

VVREF06 is used for output current reporting and loadline

loop-control. VIMON

− VVREF06 is averaged by analog low-

pass filter and then transferred to 8-bit ADC. The digitized

reporting value is scaled such that FFh=ICCMAX. RIMON,EQ

should be designed that VIMON

− VVREF06 = 1.6V while

(IL1+IL2) = ICCMAX. Additionally, sets the desired ICCMAX

by ICCMAX[3:0] of PIN-SETTING table. The PIN-SETTING

value determines intel ICCMAX register (21h) value. The

Alert# is asserted while output current exceeds ICCMAX

(VIMON

− VVREF06 > 1.6V). The behavior is masked during

DVID. For loadline loop-control, VIMON

− VVREF06 is scaled

by a percentage of Ai, that can be selected by PIN-

SETTING of Ai[1:0]. The detailed application is described

in the loadline setting section.

VCORE

ISEN1P

ISEN1N

DCR

RCS1=680ohm

IL1

ISEN2P

ISEN2N

DCR

IL2

IMON

0.6V

VREF06

ICS,PER1

ICS,PER2

RNTC

RIMON,EQ

IIMON2

IIMON1

RCS2=680ohm

VIMON

VVREF06

RT3612EB Datasheet(PDF) 26 Page - Richtek Technology Corporation

RT3612EB Datasheet(HTML) 26 Page - Richtek Technology Corporation

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