RT3607CE datasheet(43/69 Pages) RICHTEK

43 / 69 page

RT3607CE

DS3607CE-01 June 2016

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

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 poor noise

immunity. The RT3607CE provides the ramp compensation

to increase noise immunity and reduce jitter at the

switching node. Figure 20 shows the ramp compensation.

Figure 20. Ramp Compensation

Noise Margin

VCOMP

Noise Margin

IMON-VREF

w/o ramp compensation

w/ ramp compensation

IMON-VREF

VCOMP

For the RT3607CE, the ramp compensation also needs

to be considered during mode transition from PS0/1 to

PS2. For achieving smooth mode transition into PS2, a

proper ramp compensation design is necessary. Since

the ramp compensation needs to be proportional to the

on-time, the RAMP is set as

133%

400k



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 RT3607CE 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 21 shows the QR

behavior.

Figure 21. 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 the VSEN

pin which is shown in Figure 22. The QR mechanism needs

to set QR width and QR threshold. Both definitions are

shown in Figure 21. A proper QR mechanism set can meet

different applications. The SET2 can set QR threshold and

QR width by internal current source 80

μA with multi-

function pin setting mechanism.

Figure 22. Simplified QR Trigger Schematic

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

2.22 x TON QR width are set. According to Table 8, the

set voltage should be between 0.4504V and 0.4723V.

Please note that a high accuracy resistor is needed for

this setting accuracy, <1% error tolerance is

recommended. In Table 8, there are some “NA” marks

in QRWIDTH section. It means that users should not use

it to avoid the possibility of shift digital code due to

tolerance concern.

QR Threshold

QR Width

PWM1

PWM2

PWM3

PWM4

VCORE

Load

VSEN

QR Pulse

Generation

Circuit

CMP

QR_width

QR_TH

RT3607CE Datasheet(PDF) 43 Page - Richtek Technology Corporation

RT3607CE Datasheet(HTML) 43 Page - Richtek Technology Corporation

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