RT3602AE datasheet(38/46 Pages) RICHTEK

38 / 46 page

RT3602AE

www.richtek.com

DS3602AE-00 August 2017

is a registered trademark of Richtek Technology Corporation.

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 RT3602AE 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 25 shows the

QR behavior.

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 the VSEN

pin which is shown in Figure 26. The QR mechanism needs

to set QR width and QR threshold. Both definitions are

shown in Figure 24. A proper QR mechanism set can meet

different applications. The SET1 and SET2 pins can set

QR threshold and QR width by internal current source

80uA with multi-function pin setting mechanism for MAIN

and AUXI VR rails. Table 2 shows the QR_TH and

QR_WIDTH for MAIN and AXUI VR rails on the SET[1 to

2] pins.

Figure 26. Simplified QR Trigger schematic

VSEN

QR Pulse

Generation

Circuit

COM

threshold

Table 3 and Table 7 show the each VR DVID threshold

setting on TSEN_MAIN and TSEN_ AUXI pins. The each

VR DVID width is equal to 2

μs. For example, VR IMAXs

are 35A, 6A and 31A for MAIN rail, SA rail and AUXI rail,

respectively. The VTSEN_MAIN and VTSEN_AUXI need to be

set as 2.65V and 3.15V, respectively. Please note that a

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

error tolerance is recommended.

Ramp Compensation

The G-NAVPTM topology is one type of ripple based control

that has fast transient response and can lower BOM cost.

However, ripple based control usually has no good noise

immunity. The RT3602AE provides the ramp compensation

to increase noise immunity and reduce jitter at the

switching node. Figure 24 shows the ramp compensation.

Noise Margin

VCOMP

Noise Margin

IMON-VREF

w/o ramp compensation

w/ ramp compensation

IMON-VREF

VCOMP

Figure 24. Ramp Compensation

Figure 25. Quick Response Mechanism

QR Threshold

QR Width

PWM1

PWM2

VCORE

Load

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