RT8167B datasheet(29/38 Pages) RICHTEK

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RT8167B

DS8167B-00

October 2011

www.richtek.com

Figure 6. SETINI and SETINIA Pin Voltage Setting

Start Up Sequence

The RT8167B utilizes internal soft-start sequence which

strictly follows Intel VR12/IMVP7 start up sequence

specifications. After POR = high and EN = high, a 300

μs

delay is needed for the controller to determine whether all

the power inputs are ready for entering start up sequence.

If pin voltage of SETINI/SETINIA is zero, the output voltage

of CORE/GFX VR is programmed to stay at 0V. If pin

voltage of SETINI/SETINIA is not zero, VR output voltage

will ramp up to initial boot voltage (VINI_CORE, VINI_GFX) after

both POR = high and EN = high. After the output voltage

of CORE/GFX VR reaches target initial boot voltage, the

controller will keep the output voltage at the initial boot

voltage and wait for the next SVID commands. After the

RT8167B receives valid VID code (typically SetVID_Slow

command), the output voltage will ramp up/down to the

target voltage with specified slew rate. After the output

voltage reaches the target voltage, the RT8167B will send

out VR_READY signal to indicate the power state of the

RT8167B is ready. The VR_READY circuit is an open-

drain structure so a pull-up resistor is recommended for

connecting to a voltage source.

VINI_CORE

VINI_GFX

Recommended

SETINI/SETINIA Pin Voltage

1.1V

x VCC≒3.125V or VCC

x VCC≒1.875V

0.9V

x VCC≒0.9375V

x VCC≒0.3125V or GND

VCC (5V)

GND

1/8 VCC

1/4 VCC

1/2 VCC

VINI_CORE = 0.9V

VINI_GFX = 0.9V

VINI_CORE = 1.1V

VINI_GFX = 1.1V

VINI_CORE = 1V

VINI_GFX = 1V

VINI_CORE = 0V

VINI_GFX = 0V

Power Down Sequence

Similar to the start up sequence, the RT8167B also utilizes

a soft shutdown mechanism during turn-off. After POR =

low, the internal reference voltage (positive terminal of

compensation EA) starts ramping down with 3.125mV/

μs

slew rate, and output voltage will follow the reference

voltage to 0V. After output voltage drops below 0.2V, the

RT8167B shuts down and all functions are disabled. The

VR_READY will be pulled down immediately after POR =

low.

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