RT3612EB datasheet(34/47 Pages) RICHTEK

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RT3612EB

DS3612EB-02 December 2019

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Through PIN-SETTING, RT3612EB provides advanced

ramp magnitude tuning. FLRAMP_PS0[1:0] and

FLRAMP_PS1 are for PS0 and PS1, respectively.

According to different application conditions, the setting

of parameters are listed in Table 12 and Table 13. The

larger magnitude indicates larger parasitic inductance

suppression. However, larger magnitude also affects loop

response speed and reduce PWM output frequency at

loading edge. For normal PCB layout, FLRAMP_PS0[1:0]

= 00 or FLRAMP_PS0[1:0] = 11 are recommended. The

final setting must be based on actual measurement.

Table 12. PIN-SETTING of Advanced Ramp

Magnitude in PS0

FLRAMP_PS0

[1:0]

Internal Advanced

Ramp Magnitude (index)

125

175

225

Disable

Table 13. PIN-SETTING of Advanced Ramp

Magnitude in PS1

FLRAMP_PS1

Internal Advanced Ramp

Magnitude (index)

125

175

ACLL Performance Enhancement

RT3612EB provides another optional function to improve

undershoot by applying a positive offset at loading edge.

Controller detects COMP signal and compared it with

steady state. While VCOMP variation exceeds a threshold,

an additional positive offset will apply to the output voltage.

The threshold can be set through PIN-SETTING and

separately for PS0 and PS1, as listed in Table 14. The

smaller index indicates the easier detection being

triggered. The positive offset is related to the compensation.

It can approximate to

. In PS0, the slew

rate of VRAMP would increase when the VCOMP intersect

the positive offset. In order to send out another on-time

earlier to improve undershoot. In PS1, besides the positive

offset, an additional 10mV is applied to the DAC and one

pulse of PWM is also forced turn on while the function is

triggered. The positive offset and the 10mV DAC offset is

released gradually with about hundred microsecond. Figure

20 and Figure 21 show undershoot suppression behavior

in PS0 and PS1. For different platform, the optimized

setting is different. The final setting must be based on

actual measurement.

Table 14. PIN-SETTING of Undershoot Suppression

UDS[2:0]

PS0 (index) PS1 (index)

000

Disable

001

Disable

175

010

200

125

011

200

150

100

200

175

101

250

125

110

250

150

111

250

175

EA2

EA1

60mV /

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