RT3612EB datasheet(43/47 Pages) RICHTEK

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RT3612EB

DS3612EB-02 December 2019

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Over Voltage Protection (OVP)

The OVP threshold is linked with VID. The classification

table and waveform are illustrated in Table 18 and Figure

29. While VID = 0V in case of VR internal setting mode

or DACOFF or PS4, OVP is masked. When VID ramps

up from VID = 0V till the first PWM after VID settles, OVP

threshold is 2.45V to allow not-fully-discharged VSEN.

Otherwise, the OVP threshold is relative to VID and equals

to VID+350mV with minimum limit = 2.23V. While

VID<1.88V, the OVP threshold is limited at 2.23V.

The OV protection mechanism is illustrated in Figure 30.

When OVP is triggered with 0.5us filter time, controller

de-asserts VR_READY and forces all PWMs low to turn

on low-side power MOSFETs. After 60

μs from OVP trigger,

VID starts to ramp down to 0V with slow slew rate. During

the period, PWMx is not allowed to turn on.

Figure 29. Timing Chart for Over Voltage Threshold

VID

350mV

NO OVP

Minimum OVP= 2.23V

DVID UP from VID=0V

OVP threshold transition at 1st PWM after

VID settles

VID settle

PWM

OVP Threshold

Table 18. Summary of Over Voltage Protection

VID Condition

OVP Threshold

Example

Protection Action

Protection

Reset

VID = 0

(VRON = L or VR

internal setting mode

or DACOFF or PS4)

OVP is masked

VR_READY latched

low.

VCC/EN

Toggle

DVID up period from

0V to 1st PWM pulse

after VID settles

2.45V

DVID period from

non-zero VID

VID+350mV

minimum threshold = 2.23V

VID = 2V, OVP

threshold = 2.35V

VID = 1.2V, OVP

threshold = 2.23V

VID≠0

VID+350mV

minimum threshold = 2.23V

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