RT6160AWSC datasheet(4/32 Pages) RICHTEK

4 / 32 page

RT6160A

is a registered trademark of Richtek Technology Corporation.

www.richtek.com

DS6160A-02

July 2023

When VIN > VOUT, the device switches like a buck

converter. In steady-state buck-mode operation. The

on-time one-shot turns on the high-side switch S1 (S4

keeps on) and the inductor current ramps up linearly.

After the on-time, the high-side switch S1 is turned off

and the synchronous rectifier switch S2 is turned on (S4

keeps on) and the inductor current ramps down linearly.

Boost Operation

VIN

VOUT

LX1

LX2

S1 (A)

S2 (B)

S4 (D)

S3 (C)

Buck - Boost

Figure 2. Boost Operation

When VIN < VOUT, the device switches like a boost

converter. In boost mode at light load condition, the

converter turns the S3 switch on (S1 keeps on) for a

constant on-time as the one-shot is triggered, and the

inductor current ramps up linearly. After the on-time, the

S3 switch is turned off, and the synchronous rectifier

switch S4 is turned on for a certain time (S1 keeps on)

and the inductor current ramps down linearly. The S4

will turn off when inductor current drop zero. As the

loading current increases and the device operates in

continuous-conduction

mode

(CCM).

When

the

feedback signal is less than the reference, the device

turns switch S3 on (S1 keeps on) after the off-time one-

shot is cleared and the inductor current ramps up

linearly. Then the off-time one-shot turns S4 on (S1

keeps on) and the inductor current ramps down linearly.

Buck-Boost Operation

Figure 3. Buck-Boost Operation

When

VIN

≈ VOUT, all four transistors switch

continuously, the device operates in buck-boost mode.

In buck-boost mode at light-load condition, the device

turns switches S1 and S3 on, and the inductor current

increases linearly before reaching target peak-current

level. When inductor current reaches peak-current level,

the S1 and S4 are turned on for a constant time and the

inductor current decreases linearly, and then the S2 and

S4 switches are turned on to make sure the inductor will

decrease to zero level. At light-load condition, the

frequency increases as the loading increases. After the

loading current is large enough, the converter will

escape

boundary-conduction

mode

and

enter

continuous-conduction mode. Furthermore, when VIN is

close to VOUT in CCM, the switching frequency will

decrease to half of the nominal switching frequency and

the device will keep output voltage well-tracking as the

target VOUT.

RT6160AWSC Datasheet(PDF) 4 Page - Richtek Technology Corporation

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