RT6318B datasheet(5/25 Pages) RICHTEK

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RT6318B/C

DS6318B/C-01 December 2021

www.richtek.com

is a registered trademark of Richtek Technology Corporation.

Operation

Overall

The RT6318B/C is an advanced constant on-time

(ACOT®) mode synchronous buck converter. The main

control loop of the RT6318B/C using an ACOT® mode

control which provides a very fast transient response.

Internal VCC Regulator

The RT6318B/C includes a 5V linear regulator (VCC). The

VCC regulator steps down input voltage to supply both

internal circuitry and gate drivers. Do not connect the VCC

pin to external loads.

LDO

The RT6318B/C includes a 3.3V/5V 100mA linear

regulators (LDO). When VOUT is higher than the switch

over threshold 3.1V (RT6318B) or 4.7V (RT6318C), an

automatic circuit will change the power source of linear

regulator from VIN path to VOUT path.

Soft-Start

The RT6318B/C provides an internal soft-start function to

prevent large inrush current and output voltage overshoot.

The typical soft-start duration is around 0.6ms.

Over-Current Limit

The RT6318B/C current limit is fixed 9A and it is a cycle-

by-cycle “valley” type, measuring the inductor current

through the synchronous rectifier during the off-time while

the inductor current ramps down. If output voltage drops

below the output under-voltage protection level, the

RT6318B/C will stop switching to avoid excessive heat.

Output Over-Voltage Protection (OVP) and Under-

Voltage Protection (UVP)

The RT6318B/C includes output over-voltage protection

(OVP) and output under-voltage protection (UVP). If the

output voltage rises above OVP threshold or drops below

UVP threshold for longer than 20

μs (typical), the OVP or

UVP function is triggered.

Power Good

The power good output is an open drain output that requires

a pull-up resistor. PGOOD will be pulled high after soft-

start is over and the output reaches 90% of its set voltage.

There is a 10

μs delay built into PGOOD circuitry to prevent

false transition.

RT6318B Datasheet(PDF) 5 Page - Richtek Technology Corporation

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