VCTA25201B-R33MS6 datasheet(7/50 Pages) RICHTEK

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RTQ2134-QA

is a registered trademark of Richtek Technology Corporation.

DSQ2134-QA-02

May

2022

www.richtek.com

MODE Selection

Whether it is DVS0 or DVS1, there are two modes of

operation: forced continuous conduction mode (FCCM)

and automatic power saving mode (Auto mode). It is

set in the following registers: 0x49[5], 0x4B[5], 0x63[5],

0x65[5], 0x7D[5] and 0x7F[5]. For example, to set

DVS0 of Buck1 to FCCM, just write "1" at 0x49[5].

Auto Mode with Automatic Phase Adding/Shedding

Auto mode enables high efficiency at light load. At low

load current, the inductor current can drop to zero and

become negative. This is detected by internal zero

current-detect circuitry utilizing the LSFET RDS(ON) to

sense the inductor current. The LSFET is turned off

when the inductor current drops to zero, resulting in

discontinuous operation (DCM). Both HSFET and

LSFET remain off with the output capacitor supplying

the load current until the feedback voltage falls below

the

feedback

reference

voltage.

DCM

operation

maintains high efficiency at light load, while setting

MODE to Forced PWM (FCCM) operation helps meet

tight voltage regulation accuracy requirements. For

multiphase

outputs,

the

RTQ2134

automatically

increases the number of operating phases as the load

continues to increase above 3A (typ). The two phases

are interleaved with 180 degrees apart. Interleaving

reduces ripple current at the input and output.

Therefore, the input and output capacitors are also

reduced. Conversely, when the load current per phase

drops below 2.6A (typ), the RTQ2134 automatically

sheds the number of phases.

FCCM Mode

Setting MODE to Forced PWM (FCCM) operation helps

meet

stringent

voltage

regulation

accuracy

requirements. Users must enable all the set outputs

before setting into the FCCM.

UVLO, Enable Control and Soft-Start

The

RTQ2134

implements

under-voltage

lockout

protection (UVLO) to prevent operation without fully

turn on the internal HSFET and LSFET. The UVLO

monitors the voltage of AVIN. When the AVIN voltage

is lower than UVLO threshold, IC stops switching and

resets all digital functions.

The RTQ2134 provides an EN pin, as an external chip

enable control, to enable or disable the device. If VEN is

held below a logic-low threshold voltage (VENL) of the

enable input (EN), the converter will enter into

shutdown mode and reset all digital function (I2C); that

is, the converter is disabled even if the VIN voltage is

above VIN under-voltage lockout threshold (VUVLO).

During shutdown mode, the supply current can be

reduced to ISHDN (20

A or below). If the EN voltage

rises above the logic-high threshold voltage (VENH), the

device starts switching. When appropriate voltages are

present on the VIN, AVIN, VIO and EN pins, the

RTQ2134 will begin digital function, switching and

initiate a soft-start ramp of the output voltage. After the

device is turned on and VIO is ready, all digital

functions including I2C communication start to work in a

boot time with 230

s (typ.). The voltage of VIO can be

used to supply power to digital function and it is

recommended that enable the device after VIO voltage

is ready. The RTQ2134 supports enable delay time

setting (factory setting) and soft-start slew rate setting

for each Buck. The soft-start function is used to prevent

large inrush current while the converter is powered up.

0x55[5:4],

0x6F[5:4]

and

0x89[5:4]

let

soft-start time of each be programmable. The start-up

sequence is shown in Figure 3. IC also implements

enable control by software, it can be set in the registers:

0x49[0], 0x4B[0], 0x63[0], 0x65[0], 0x7D[0] and 0x7F[0].

If the output voltage of Buck is default disable which is

only set by factory, the output voltage starts to ramp up

by software and the Figure 4 shows the start-up

sequence. For disable function, the device supports

disable delay time setting (factory setting) by external

EN pin and the output voltage ramps down with default

discharge resistor. The discharge resistor can be

controlled to on or off by register 0x42[0], 0x5F[0] and

0x79[0] when the converter is disabled by software.

The power-off sequence is shown in Figure 5 and

Figure 6.

VCTA25201B-R33MS6 数据表(PDF) 7 Page - Richtek Technology Corporation

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