RT4832AWSC datasheet(17/26 Pages) RICHTEK

17 / 26 page

RT4832A

is a registered trademark of Richtek Technology Corporation.

DS4832A-00

January

2017

www.richtek.com

Discharge and Short to GND Function

The RT4832A provides internal switch resister to

discharge voltage of VPOS and CPOUT during the

channel power off. Set the 0x0C[4] = 1 for VPOS

discharge enable and 0x0C [1]=1 for CPOUT discharge

enable. When the voltage discharge to GND, set the

0x0C[5] = 1 and 0x0C[2] = 1 will keep the output

connect to GND.

Power Saving Mode

The RT4832A provides the power saving mode to

bypass the input voltage to VPOS. Enable the 0x0C[7]

= 1 to control the high side switch of boost converter

and the LDO fully turn on to save the quiescent current

and switching current. The POS is equal to Vin and

CPOUT is equal to

–Vin when power saving mode.

Delay Time Control of POS & CPOUT

The RT4832A provides the delay time control between

POS and CPOUT power on and off. The bits of the

0x0D[7:6] is used to set the delay time. Table 3 and

Figure 2 shows the delay time and the sequence for

DSV power on and off.

Table 3. DSV Delay Time Control Table

0x0D[7:

Delay time

Power on

Power off

constraint

POS start ramp up when ENP = H or

dsv_vpos_en = 1,

CPOUT start ramp down when ENM

= H or dsv_vcpout_en = 1.

CPOUT start discharge when ENM = L or

dsv_vcpout_en = 0,

POS start discharge when ENP = L or

dsv_vpos_en = 0.

1ms

POS start ramp up when ENP = H or

dsv_vpos_en = 1

CPOUT start ramp down after POS

ramp up to target and delay 1ms even

the ENM = H or dsv_vcpout_en = 1

CPOUT start discharge when ENM = L or

dsv_vcpout_en = 0

POS start discharge after CPOUT discharge to

GND and delay 1ms even the ENP = L or

dsv_vpos_en = 0

2ms

POS start ramp up when ENP = H or

dsv_vpos_en = 1

CPOUT start ramp down after POS

ramp up to target and delay 2ms even

the ENM = H or dsv_vcpout_en = 1

CPOUT start discharge to GND when ENM = L

or dsv_vcpout_en = 0

POS start discharge after CPOUT discharge to

GND and delay 2ms even the ENP = L or

dsv_vpos_en = 0

5ms

POS start ramp up when ENP = H or

dsv_vpos_en = 1

CPOUT start ramp down after POS

ramp up to target and delay 5ms even

the ENM = H or dsv_vcpout_en = 1

CPOUT start discharge when ENM = L or

dsv_vcpout_en = 0

POS start discharge after CPOUT discharge to

GND and delay 5ms even the ENP = L or

dsv_vpos_en = 0

Periodic Mode

The RT4832A supports the DSV periodic mode with

the enable bit 0x08[7] and frequency select bit 0x08[6].

In the periodic mode, the enable channel of the POS

and CPOUT repeat on/off. The delay time, slew rate,

discharge and GND connect follow the register setting.

Table 4. Periodic Mode Control Table

dsv_periodic_mode

0x08[7]

dsv_freq_pm

0x08[6]

ton (ms)

tperiod (ms)

1.6

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