High-Performance PWM Controller

EC3228

Page 2 of 16

3G15N-Rev.P002

Pin Assignments

GND and Thermal Pad (connected to GND plane for better heat dissipation)

PIN NO

NAME

FUNCTION

1

POK

Power Good Output. POK is an open drain output used to indicate the status of the

output voltage. Connect the POK in to +5V through a pull-high resistor.

2

OCSET

Current-Limit Threshold Setting Pin. There is an internal source current 10 uA through

a resistor from OCSET pin to GND. This pin is used to monitor the voltage drop across

the Drain and Source of the low-side MOSFET for current-limit.

3

EN

Enable Pin of The PWM Controller. When the EN is above enable logic level, the

Device is workable. When the EN is below shutdown logic level, the device is in

shutdown and only low leakage current is taken from VCC and VIN.

4

FB

Output Voltage Feedback Pin. This pin is connected to the resistive divider that set the

desired output voltage. The POK, UVP, and OVP circuits detect this signal to report

output voltage status.

5

RF

This Pin is Allowed to Adjust The Switching Frequency. Connect a resistor RRF

to

set switching frequency as show in Table1. The pin also controls forced PWM mode

or PFM/PWM auto skip mode selection. When RF pin is pulled down to GND, the

device is in automatic PFM/PWM Mode. When RF pin is pulled high to POK, the device

is in force PWM mode.

6

LGATE

Output of The Low-side MOSFET Driver. Connect this pin to Gate of the low-side

MOSFET. Swings from GND to VCC.

7

VCC

Supply Voltage Input Pin for Control Circuitry. Connect +5V from the VCC pin to the

GND pin. Decoupling at least 1u F of a MLCC capacitor from the VCC pin to the GND

pin.

8

PHASE

Junction Point

of

The

High-side

MOSFET

Source,

Output

Filter

Inductor

and

The Low-side MOSFET Drain. Connect this pin to the Source of the high-side

MOSFET. PHASE serves as the lower supply rail for the UGATE high-side gate driver.

9

UGATE

Output of The High-side MOSFET Driver. Connect this pin to Gate of the high-side

MOSFET.

10

BOOT

Supply Input for The UGATE Gate Driver and An Internal Level-shift Circuit. Connect to

an

external

capacitor

to

create

a

boosted

voltage

suitable

to

drive

a

logic-level N-channel MOSFET.

Exposed

Pad

GND

Signal Ground for The IC