RT3607BC datasheet(39/60 Pages) RICHTEK

39 / 60 page

RT3607BC

DS3607BC-01 June 2018

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Figure 24. Quick Response Mechanism

The output voltage signal behavior needs to be detected

so that QR mechanism can be trigged. The output voltage

signal is via a remote sense line to connect at VSEN pin

that is shown in Figure 25. The QR mechanism needs to

set QR width and QR threshold. Both definitions are shown

in Figure 22.Aproper QR mechanism set can meet different

applications. SET2 can set QR threshold by internal

current source 80

μA with multi-function pin setting

mechanism. SET3 can set QR width with external voltage

divider.

Figure 25. Simplified QR Trigger Schematic

VSEN

QR Pulse

Generation

Circuit

CMP

QR_width

QR_TH

QR Threshold

QR Width

PWM1

PWM2

PWM3

PWM4

VCORE

Load

RAMP Setting

RAMP plays an important role in the balance of loop stability

and transient response. It also helps to smooth power

state transition process. The ramp height should link with

switching frequency. After switching frequency is decided,

the ramp still can be slightly adjusted to fine tune

performance. The RT3607BC provide RAMP setting

function through SET2 pin. SET2 are used to select more

specific switching frequency for CORE rail. Table 7

describes Ramp setting in SET2 pin. Figure 23 shows

the ramp compensation.

Noise Margin

VCOMP

Noise Margin

IMON-VREF

w/o ramp compensation

w/ ramp compensation

IMON-VREF

VCOMP

Figure 23.

Quick Response (QR) Mechanism

When the transient load step-up becomes quite large, it

is difficult for loop response to meet the energy transfer.

Hence, that output voltage generate undershoot to fail

specification. The RT3607BC has Quick Response (QR)

mechanism being able to improve this issue. It adopts a

nonlinear control mechanism which can disable

interleaving function and simultaneously turn on all UGATE

one pulse at instantaneous step-up transient load to

restrain the output voltage drooping. Figure 24 shows the

QR behavior.

For example, QR threshold 20mV/10mV at PS0/PS1

(Ramp Offset Setting = +0kHz) According to Table 8, the

set voltage should be 0.45V. 0.88 x TON QR width (Enable

PSYS, DVID width = 24

μs) According to Table 3, the set

voltage should be 1.075V. Please note that a high

accuracy resistor is needed for this setting accuracy, <1%

error tolerance is recommended.

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